Announcement

**Fair!** · 07-10-2025, 11:36 AM

continued from above

SN95 CAMBER PLATE + REAR SHOCK MOUNTS

In May of 2025 we had Chris' 1995 Mustang GT in our shop getting a set of MCS remote double adjustable coilovers installed. But these were not the typical "eye to eye" rear shocks that most folks order, which we've sold many times for the Fox or SN95 cars. We ordered a eye-lower and pin-upper rear shock to be able to make a proper spherical shock mount for the upper mounting position - which we have released for the SN95 and will soon make a Fox version of.

This uses a derivative of our C6 Corvette Z06 / NC MX5 spherical shock mount, which we CNC machine in-house here at Vorshlag. This design is unique in that it moves the spherical bearing above the sheet metal - which requires some modification to the car and/or to a mounting tower to make work. These have proven to fix some issues on those two chassis which otherwise are almost always using a rubber or poly upper mount - which is never desirable in any sort of Motorsports use. The sloppy bushing movement soaks up damper travel and delays them from doing any work.

We made this new mount and a drilling fixture to help add the 45mm dia hole, and offset the mount away from the tire for more clearance to use a real coilover shock. This includes a reinforcement plate that is tack welded to the car, and we stitch welded the rear shock tower to the wheel tub and frame rail to reinforce all of that for suspension loads vs damper-only loads with the stock "divorced" spring.

Another major development we made for this car was a radically different camber plate for the SN95 chassis. Unlike virtually all offerings from the past 30 years, our design does NOT sit above the strut tower. This means we don't need to drill a 4th hole and mount the plate above the tower. This also means that there are not "point loads" from top mounting - so the bolts are NOT in tension. Instead, the normal impact loads from bump travel go through the main plate from underneath - doing a better job of spreading these loads to the tower. This design also gains a substantial amount of shock travel over "eye" mounts with a conversion adapter that sits under the shock tower.

We started with a new design idea, made the main plate and lower bolt ring out of steel quickly, then test fit these to the SN95's right front strut tower. On this one we did add the 4th hole but our production unit will not need that. After testing this mock-up design on the car (above) we noticed that the previous camber setting of -2.5 deg was nearly doubled to -4.7 deg - without modifying the strut tower. We immediately moved to CNC production of an aluminum main plate and top pointer ring.

Since our main camber plate design is not placed ABOVE the strut tower, our included radial bearing spring perch just sat on the top step of the strut - without the need for inches of spacers. We did it the Vorshlag way, which has worked great for 20 years and tens of thousands of camber plates on other car models. The spring length is super long for coilover Fox/SN95 cars, so thse don't need the extra strut travel up front, meaning the "above tower trick" for camber plate mounting is not needed.

We still have one more design iteration to get this to production, but it should be ready by Q3 2025. While the Mustang was here we did a few other tasks beyond the MCS install, prototype camber plate install, and rear spherical shock mount install. When it was all wrapped up we took the car to get an alignment check at a nearby shop.

We increased the front camber from -2.5 to -4.4 deg of camber, which made the 345mm Vitour P1 tires on 18x12" wheels fit a bit better. Chris is planning on some flares in the future, but for now the fat tires just hang out in the wind a bit.

The customer Chris was so happy with the MCS + Vorshlag parts, and he left our shop to go run a track event at Hallett (a 1.8 mile track in Oklahoma). Straight away was 3 seconds faster than his previous Personal Best, and never touched a knob on the MCS dampers! Now he's looking to tackle an ABS upgrade (his SN95 ABS was deleted long ago), which we're working on with this Fox - we will have something for the SN95 in the future as well.

THE GENERAL SUSPENSION PLANS FOR THE FOX

Without being cagey, I'm not going to share much about our plans other than the obvious - we're going to make a Fox camber plate design that hopefully fills a niche and solves some problems. We've already scanned the strut towers of our 1988 Fox and have a design in the works, which we will install in the coming weeks.

Another thing we want to tackle is a new tubular K-member design using some 21st Century uprights and design aspects - unlike anything on the market today. The factory Fox front crossmember is very large and restrictive in many ways (like header clearance) but it very strong. All of the front suspension lateral loads and much of the engine torque and braking pass through this steel assembly.

As we've found out in some early engine swap research, none of the current long tube header designs will fit the stock crossmember. There used to be a Hooker header that did, but parent company Holley ditched all exhaust related components a few years back. We bought some cheap eBay headers but can clearly see that, like the offerings from Speed Engineering, ARH and others - they only fit with a handful of "drag race oriented" tubular K-members, which leave a lot of strength out of the equation in the search for weight loss.

We have worked with some of these drag race crossmembers and they tend to break in real road race Mustangs, like the Fox shown above. The lack of structural support in these crossmembers is crucial, and we have repaired and upgraded more than a few of these. For drag racing these crossmembers can work fine, but for road course or autocross use with modern tires that can reach 1.5g without aero loads, those will flex and bend too much to be useful.

The existing Maximum Motorsports K-member (above) is MUCH stronger, and it has been the go-to for corner carvers for the Fox and SN95 for ages. We have purchased and installed these on cars to replace the drag race versions. But as great as the Maximum unit is, we want to do something with newer uprights and suspension geometries that haven't been done yet.

Out back the 4-link OEM suspension and solid axle are just so, so bad. This was a cheesy suspension design even in 1977 (from the Ford Fairmont). The auto-bind geometry of the opposed 4 link is well known and I'm not gong to rehash that here. When I worked at Houston Performance in the late 1990s we often installed a panhard bar and torque arm - suspension design fixes dating from the 1960s - and that improved handling a bit, but brought their own negatives. We have even done some of that at Vorshlag (above right), Again, I'm not going to go into all of that, but even the best solid axle Band-Aids have big downsides.

The popular "upgrade" for a long time was to yank the stick axle and swap in the complete 1999-2004 SN95 Independent Rear Suspension, or IRS. Sadly, the geometry of this is still pretty compromised - they axle hop pretty badly under power, so much so that the drag racers of these later Cobras would pull them and sell them to track folks.

Out back we also want to adapt 21st Century designs to fit the Fox chassis without much if any cutting or fabrication by the end user. I love the S550/S650 rear IRS setup, due to some very favorable geometry and much less unsprung weight. There is both camber and toe adjustment, and we can actually USE negative rear camber to make these cars faster. Also, IRS doesn't make the rear springs on both sides "additive in bump", so we can run a stiffer rate without wrecking ride quality.

Compared to the Fox's solid axle, however, the S550 IRS setup is just SO FREAGIN WIDE. And it isn't just as simple as narrowing the subframe or arms to fit the much narrower Fox chassis - that wrecks the rear suspension geometry, and this route may prove impossible. We have three rear subframes and suspensions from modern chassis (including the S550) at our shop, which we are 3D scanning and modeling. We'll get something proper designed and fabricated, just stay tuned. I've wanted to do this for a DECADE and now we have the resources to complete this.

No lie, this is a big engineering task (the IRS and the front suspension work), but we are investing the time and money to do this - new 3D scanning tools, more engineering manpower, more fabrication equipment. We're going to have the entire fox chassis scanned as well as the the 3 rear subframes and IRS setups modeled soon. This major suspension design work will happen after we complete a quick V8 swap, get that running and tuned, and perform a series of baseline and track tests on the existing 245mm Firehawk 300TW tires. We have to do this because our first track test with the 2.3L was SO BAD as to be completely meaningless.

WHAT'S NEXT?

We always do a baseline track test at the same track, going back 20 years - Motorsport Ranch Cresson's 1.7 CCW course - my home track, where I have driven thousands of laps and set probably ~15 class track records. I was going to include the first track test in this first installment, but it was SO BAD that I will save that for next time. Embarrassingly slow!

If I can find another stock Fox Mustang V8 from 1987-1993 to take out and get a baseline, I will. Otherwise we'll do it with the 500 hp LS and TKX installed, in the next 6-8 weeks. We do have our 2nd and 3rd journal entries for the 21st Century Fox Diary on YouTube, and the 2nd is linked below.

You can click the image above for the linked video - matter of fact, ALL images in my forum posts going back 25 years can be clicked for higher res images (these always look better on a larger PC than a tiny phone). Before you turn your noses up, yes - our engine swap will be an aluminum LS1 made by General Motors (well, a hotted up one built by HPR). I like to call the LS a "Gen2 Windsor", because they share more geometry with the 351W than earlier Small Block Chevy engines - heck you can swap LS and Windsor cylinder heads across the respective blocks.

The 2.3L + T5 is already out and an LS with a Tremec TKX is already installed, just needs all of the plumbing and wiring. We will have mounts for our new front crossmember (and possibly swap headers) to fit the LS V8, Coyote 5.0L, and 302/351 Windsor engines. And soon we will have a proper transmission crossmember for the TKX (the current offerings aren't great). PLEASE don't get hung up on the engine - this V8 is a necessity right now, as our 2.3L died in our first track test, and it was too slow to give us a meaningful baseline to compare to.

We will share more next time - thanks for reading!

Terry @ Vorshlag

**Fair!** · 10-06-2025, 03:18 PM

Project Update for October 6, 2025 - Lots to catch up on for the last few of months. We have nearly completed a V8 swap and a lot of other tasks, much of which has nothing to do with the engine swap - and might be worthwhile for some viewers on their own project cars. The first post in this thread was a bit long, and had a lot of "plans" - this is all tech, which we will start off with the first track test in June of 2025 (which was pretty awful).

Some of you might read this and think "Hey - I could have finished this V8 swap faster", and you might be right. The difference here is that we're finishing each system we touch to a pretty high level - think "car show worthy + highest levels of Motorsports safety", and that takes time. We are also in the middle of four other shop builds, plus customer work, and we attack this project as time permits.

So let's kick this forum update off with this car's first track test, then dive into the many systems we are upgrading, repairing or throwing away and replacing.

"BASELINE LAP" TRACK TEST - JUNE 8, 2025 - MSR-C 1.7 CCW

We took the little Fox to the track to get a baseline lap at Motorsport Ranch Cresson's 1.7 CCW track, which I have been driving at for 25 years and have made 1000+ laps on. Not a brag, just that I know this track well and "learning the lines" isn't an issue for me here. I have set many class track records here in dozens of cars, and have a club membership here - so I can go on "member days" and get laps without much traffic (like I did on this Friday morning).

I like testing here because on member days they do 30 minute sessions and at 1.7 miles it makes for a short out lap and in lap, so I can often come into the pits and make changes and go back out several times in a session. I will sometimes swap cars during a session, and only get charged for one session fee ($25).

As stated before, the only changes to the stock 1988 Mustang (covered last time) were fresh 245mm Firestone Firehawk 300 treadwear tires on 17x9" wheels and some RockAuto semi-metallic front brake pads. We replaced or fixed things like the battery, some wiring, new fuel filter, pushed some brake fluid to bleed the system, but otherwise it was stock.

Number one thing I noticed right as I was going out on track - the oil pressure gauge was not working (above left - see the engine, running but oil pressure is near zero). Hmm, I don't remember that on a test drive earlier, but who knows? It is a 37 year old car, probably a flaky sensor. We had half tank of (really old) gas, tires were set at 34F/28R psi on these sticker new Firestone Firehawk 500s (300 treadwear). Ambient temps were 77F, and Amy was there with me shooting pictures.

I drove for 3 full laps and pushed the car hard each lap. The lack of power was SHOCKING and it would not exceed 74 mph no matter what I did. Redline is 4000 rpm with this 2.3L tractor motor. I've gone faster around here in my tow vehicle, this was just DISMAL. I was Wide Open Throttle in many corners not normally possible, just barely needed the brakes, but when I did have to slow the car would brake dive hard. Ahh... memories. The roll in the rear was painful, but the 2.3L car had no rear swaybar.

I am kind of amazed at how slow this car is. Most modern pony cars will do a 1:25 lap here and I've run 1:18 in our '24 Darkhorse and 1:13.2 in my S550 Mustang on Hoosiers. This 1:52 lap is an outlier - I have nothing to compare it to. "Luckily" the engine crapped out on my 4th lap - I panicked thinking I had hurt the engine. I realized this engine is barely worth scrap metal cost anyway, no fluids were pouring out, and I managed to re-fire it and limp it into the pits and back in my trailer.

I had planned on making more laps, coming in to check and bleed down tire pressures, but it just didn't matter. It was painfully slow and this "baseline" lap is just not worth comparing to. We talked about it back and the shop and decided to put a V8 into this car, make no other changes, and come back to get a true "stock suspension" baseline lap with real power.

PLANS FOR A V8 UPGRADE

Now the powerplant upgrade was not supposed to happen at the beginning of this project, and it will never be the focus of this Vorshlag build. The main goal is to develop some 21st century suspension options (both front and rear) for the 1979-93 Fox chassis. To quantify any changes we always start with a Baseline Lap at MSR Cresson 1.7 CCW, then test things at every stage of development.

But our baseline laps from June were completely useless, due to the 2.3 liter four cylinder, which might have been putting out 80 hp at the start of the track test. In hindsight we made a clear mistake. While we replaced the brake pads, tires, and brake fluid, and even changed the fuel filter, we neglected to clean out the fuel tank. I had forgotten that it had been sitting outside under a tarp for close to 4 years - and gasoline doesn't sit that long and work well. Even with an unclogged fuel system, however, the 4 cylinder power was never going to put down any meaningful lap time to compare to.

I loved the Small Block Ford (SBF) and Coyote engines I have owned over the years, but they have downsides. Instead of finding a period correct 1987-93 Ford 5.0L engine, changing everything to make that work in this car, we're short cutting a bit to a lighter all aluminum LS V8 and Tremec TKX 5-speed manual. We had always planned for some sort of aluminum V8 - Coyote or LS - and an 383" LS from another project was almost complete at HPR so we're going that route.

I'm not here to sell anyone on any sort of engine or swap. I've got a lot of years using SBF engines, like above left where we were swapping in a new longblock into my 1987 LX in 1993. That pic has engine builder Erik Koenig (HPR) where lots of engines of all makes get built. The issue with any Ford engine options are simple: weight and size. The Fox shown above right is one of our customers' with a Coyote 5.0 swapped Fox, and the engine takes up the entire engine bay, with no room for a traditional vacuum brake booster. The smaller SBF is heavier because it has an iron block, but you can spend $$$ to build an all aluminum Windsor that can make similar power (the Ford Z351 aluminum Windsor block is a staggering $7000!)

ALL-ALUMINUM GEN2 WINDSOR V8!

Some people get real funny about cross make engine swaps, which is funny to me - because the OEMs do these things all the time. The Toyota GR86 has a Subaru engine. The Mazda NC MX5 has a Ford engine. I could give 100s of examples, and you folks only get your feathers ruffled when some hot rodder does what hot rodders HAVE ALWAYS DONE and perform an engine swap that isn't blessed by some auto maker. WHO CARES!? The time clocks on a race track sure don't give a fig what is stamped on a valve cover. Get over it - or call this GenIV LS a "Gen2 Windsor", as these things share more geometry with the Windsor than they do with the old Small Block Chevy. You can swap the cylinder heads back and forth without much effort!

We are using an all aluminum LS mostly because 1) this car had a dreadful four cylinder and 2) because the LS is light, compact, and we already had one in process at HPR. If we had started with a 5.0L SBF powered car we wouldn't be messing with the LS swap we are doing now (but we would have still done it eventually). We will make our planned new front K-member available with engine mounts and header options for the big 3 options: SBF, Coyote, and LS.

The original 2.3L + T5 drivetrain was removed June 26th out and a mock-up LS1 and the Tremec TKX were installed July 1st. The Tremec 5-speed transmission (with 600 ft-lbs of torque capacity!) was in another project that has been back burnered, and will work nicely in the little Fox chassis.

OIL PAN AND HEADER TESTING

On July 1st we had the old 2.3L + T5 drivetrain out and it was time to test some parts to see which headers and oil pan needed to go onto the LS1 engine we have planned.

We bolted up the Tremec TKX and bellhousing we had in another project to a "mock up" LS block and heads, which are made from a windowed block and some old heads. We added a 4th gen Camaro (1998-2002) oil pan to this engine for our first mockup.

The 4th gen F-body pan does not fit - as expected and shown above. We were told this wouldn't work with the stock Fox crossmember, but I am always of the mind of "trust but verify" if someone cannot show me pictures - like the two above. So many forums where this level of detail might exist are sadly gone. I was otherwise happy with the overall fit of the drivetrain, and the shifter on the normal TKX location lined up with the hole in the floor of this manual car.

At this point we just made some wooden shims and set the engine and transmission in place - at the wrong driveline angle and lateral placement, but its a close approximation. With a spare intake installed we could finally see we had more hood clearance than we had hoped, and a few other things could be checked. I might go with a taller intake than originally planned, to utilize this vertical space.

Jason had spoken to the Holley tech while they were developing their swap parts and knew that Holley had a pan with minor changes that fit the stock crossmember, which was verified on an Ls swap mustangs FB group that this Holley 302-5 oil pan would work with the stock crossmember, and sure enough, it is stated to be made for this exact swap. Holley used to offer lots of things, like long tube headers and a transmission crossmember, which were made for an LS in a Fox with the stock front suspension crossmember, but they got spooked (by the EPA?) and dropped most of these parts. The oil pan was still available, so I bought that.

On July 7th we received the 302-5 oil pan and an ARP oil pan bolt kit for an LS and we got it bolted to our mock-up LS engine, and stuffed that back into the Mustang. Now we could test proper driveline angles and do more detailed driveline placement tests.

This Holley pan was the perfect wet sump oil pan for this LS engine, in the Fox chassis, with a stock crossmember. The engine was offset to the passenger side in some of the above pics, trying to make some headers fit. Again - most folks would immediately swap to an aftermarket front crossmember for any sort of track or drag race build in a Fox, all of which add loads more clearance.

But here, we are just trying to get this on track with the STOCK SUSPENSION, and the tubular crossmembers all require coilovers, as they ditch the stock inboard spring mounting pockets. We're stuck with the chunky Ford crossmember for now. We will be making a new tubular crossmember soon, of course, and it will become obvious why we're doing that when we finish that.

Earlier I took a gamble and ordered these $217 long tube stainless headers made "for a '79-93 fox and '94-04 SN95 LS swap". I found these from several vendors and they are all clearly Chinese built. It was so cheap I figured it was worth a try, and nowhere did any of these entries say what is really needed to make these possibly fit: an aftermarket, tubular crossmember. They looked pretty good, to be honest. How does anyone in this chain of manufacturer + reseller make any money at this price? Sweat shop labor and cheap materials is how.

Of course $200 eBay headers will absolutely not fit without the tubular crossmember or major rework, but that was a low risk gamble. We don't feel like chopping up these headers and "making them fit".

This $217 header purchase was still a very low risk gamble. All of the folks on socials saying "just make them fit" or "just build custom headers" as we were showing this in real time have done neither tasks. Making an LS swap kit is absolutely NOT our goal here. We've done this level of rework on cheap headers on other projects before, and it was always a huge time suck - figure 20-30+ hours minimum to modify these and make them hold vacuum, and possibly more hours than that. We are not going to burn those sorts of hours modifying $200 eBay headers.

That day after testing I made our 3rd journal entry video (linked above) - it is less than 2 minutes, showing much of what I just explained above about the oil pan and header testing.

I rolled the dice a second time in early July when the header test fit went sideways and ordered these $114 cast iron "LS3" manifolds. They are heavy but they actually fit, and the LS1 and LS3 exhaust ports are close enough in shape and size to not matter. We now know that these do fit and those in in late July with the actual built LS engine, no longer needing this just mock up longblock. I'll show that further down with the exhaust work.

Once we knew the 302-5 Holley pan was the right option, I ordered an Improved Racing baffle kit, made to fit this 302-5 pan and the 302-3 variant (with oil drain back holes for turbos). After test fitting the baffle to the pan (below left), I took the 302-5 Holley oil pan + pickup and the Improved Racing 302-12 baffle kit to the guys at HorsePower Research, who were wrapping up the little 6.3L LS engine.

At HPR, Alec modified a stock LS windage tray (above right) to clear the very short front section of the oil pan. There is no windage there because this oil pan just clears the 4.0" stroke crank. The Holley pickup screen was checked for depth with clay - it had the .250-.300" clearance to the bottom of the oil pan we want. The Holley pan was installed and buttoned up along with a new front cover.

continued below

**Fair!** · 10-06-2025, 03:18 PM

continued from above

FUEL TANK REFRESH AND UPGRADES

This was the crucial step we skipped in the earliest stage of this build, and that could of at least allowed the 2.3L engine to run wide open and possibly achieved more than 74 mph terminal velocity. Live and learn! Like I mentioned above from our June track test, we should have dropped and cleaned out the tank earlier, but instead we just swapped the fuel filter and sent it. On July 14th, we finally dropped the tank to properly clean it out.

The fuel sock from the stock pump was completely disintegrated. And now the lack of power on lap 4 of our track test with the 2.3L makes more sense. I mean, sure... the oil pressure gauge read zero the entire time, and I thought it was a busted gauge. Until it started working on lap 4, and showed the low numbers. But the engine never made any clatter, just felt way down on power.

Now I suspect the fuel injectors or new filter were simply clogged from the sock coming apart - and the engine stopped making power. Here we drained the stinky fuel and power washed the insides of the tank and it looks spotless. I ordered a "drop in replacement" Aeromotive pump kt and a new level sensor, which will be installed next.

The stock tank looked pretty solid, but it had one busted spot weld for the "fuel pump basket" mounted inside - if you shook the tank the basket would bang against the top. Myles fixed that with a small drilled hole through the spot weld, then TIG welded the tank to the basket. And covered up the hole with a rosette weld. Brad wire brushed the exterior of the tank, then sprayed it with self etching primer.

He then hit it with a coat of Duplicolor aluminum silver "engine paint with ceramic", and it looks good as new. Would it have been smarter to buy a new tank from Summit for about $130 delivered? Probably, but you never know what you are going to get with the cheap import replacements. This one was good for 37 years of service - and now should be good for 37 more.

Here the Aeromotive 340 lph pump assembly was installed. The new pump assembly drops into the high spot on the right side in place of the stock pump. Above left, Brad is looking inside the tank to see which way to clock the fuel sock filter, so it lines up in the "basket" properly.

The images above were taken through the fuel level fill hole on the side, and the above left image shows the top of the Aeromotive assembly bolted in place. I show these because the instructions suck and we couldn't find good pictures, and this took some trial and error. The right side picture above shows the stainless steel arm holding the pump and sock, which are nested down inside the basket. The black corrugated return hose drops right into the basket - which acts almost as a surge tank, but not quite.

We replaced everything that went into the tank - because 37 years submerged in fuel will rot anything. The new RockAuto sourced fuel level float assembly went into the center opening, which is on a lower level on the top of the tank.

I showed some images of the tank going together on a FB group called "79-04 Mustangs Road Race-HPDE-AutoX" and a user there pointed out (that's his picture, below left) that the replacement fuel tank vent we have - OEM sized - might be insufficient for the 340 lph pump that we're using.

Instead of finding out the hard way, I ordered the Breeze Automotive "big bore vent valve" kit he recommended for $49. It is considerably larger and we will plumb this to a custom charcoal canister we are building, which I will show below.

The last item that touches the stock fuel tank is the filler neck. This was removed from the chassis and cleaned up, then a new rubber gasket that mates the steel tubular neck to the tank was installed. The best advice is - if you have to drop the tank and you don't remember if the gasket is new, you should just replace it.

WEIGHTS OF ENGINES

I have an obsession with weights, and of course we weighed the engine + transmission coming out as well as what went back in. I thought this was interesting

We will get into more on this engine in another section, but you might notice that the all aluminum LS V8 + TKX weigh less than the 2.3L and glass T5.

STICK AXLE FUN

This 1988 Mustang had the 2.3L 4 cylinder, which means it came with a 7.5" ring gear axle housing and an open differential. We plan to design a new IRS setup out back (not '99-04 Cobra based) but want to complete a couple of track tests with V8 power and the stock rear stick axle, and I don't want an open diff that might explode with the power we're adding.

We went hunting for a 4-lug 8.8" ring gear 1987-93 Mustang stick axle out of a V8 car. This means FB Marketplace, as every other local used parts selling platform is dead (RIP Craigslist).

First one I found for $250 was impossible to meet up with the guy, but the second one for $300 (talked down from $400 once we arrived) worked out well. This one has the super common 3.08:1 gears, the limited slip still works, and it came with all of the arms and even the qudra-shocks. We power washed and weighed it at 236 lbs as shown above, and the open diff 7.5" came in at 172 pounds - shown below, but without the 4 shocks and no rear swaybar.

The 8.8" limited Slip rear axle was checked out, cleaned, and installed into the 4 cylinder car. Adding the rear swaybar that came with this is a nice bonus, as this suspension is super soft and has tons of roll. We checked the original 4 cylinder rear springs on our digital spring rater at 142 #/in and the V8 springs (it only came with ONE with the axle) at 185 #/in. We only had a complete pair of 4 cylinder springs, so those went in for the "stock baseline" track tests.

The above two pictures show the 8.8" axle with two different brake hard line setups. At left is the setup that normally comes on the V8 cars, with the junction for the rear circuit on the driver's side. We swapped over the rear brake hard lines and junction from the 4 cylinder's axle to line up with a hard line to the front on the passenger side of this chassis. That won't affect hydraulics at all, just makes it easier to use the lines on the chassis for the next track tests.

Another discovery (re-remembering?) was finding that the 4 cylinder shocks (the dirty ones, above left) are different, and have a thicker "eye" at the bottom and mount with a different bracket perpendicular to the axle. The V8 shocks have a different bracket at the axle and a thinner eye. The 4 cylinder shocks were completely blown.

So I bought the cheapest pair of Fox V8 twin tube rear dampers from RockAuto at $17.84 each, and those are on the car for the next two track tests. Nothing but the best for #TheOcho!

The shocks arrived and that allowed the 8.8" to finally be bolted up and ready for a driveshaft mockup and measurements.

REAR CHASSIS 3D SCANNING

When we had the axle out in the step above we took the time to do some scans. Myles added a bunch of our magnetic tracking dots and some talc + alcohol spray for a matte finish on the surfaces. Then the Einstar Vega was used once again to pick up details on the rear frame sections, floor, and all pick-up points.

We also had rounded up several modern OEM Independent Rear Suspension subframes and we mocked those up in the bare rear chassis. This has ruled out one of the hopefuls, but we do have some good ideas of where to go next. We never planned to just "stick a subframe" out back and make it fit, no we will make a subframe. This mockup just gave us some ideas of potential interference.

The goal is to use rear uprights and basic geometries from a 21st century chassis' IRS that has an abundant supply of the OEM parts we will build around, aftermarket support for arms (that we will make or have made to our specs), and use the center differential housing we want (Ford based). Rear hubs with the same 5 x 114.3 bolt circle and better rear brake caliper and rotor options is a plus. More on this after the next two track tests.

FLOORPAN CLEANUP + REPAIRS

If you noticed a filthy floorpan in the pictures above, you are not alone. 37 years of a leaking rear engine seal and valve cover coated the middle of the chassis in oil and grime. This is the nastiest part of this chassis, as we've power washed the engine bay and front subframe to be spotlessly clean.

The mock up engine and transmission were out so we rolled the Fox outside on a hot July day and Brad jacked up one side at a time and power washed it, after soaking it with degreaser.

The underside was now "clean" but about half the undercoating is still attached. If you look at the top pic when it was greasy, the undercoating is gone only where the oil spot used to be. That gave me an idea - let's soak it for 24 hours with WD-40!

Plastic drop sheet was taped under the car and a full "big blast" can of WD-40 was sprayed on the remaining undercoating. This mild solvent was sprayed on liberally and allowed to soak and drip overnight. The hope was this would soften the undercoating so it could be removed.

The next day Brad used some plastic scrapers and grout brushes to soften the WD-40 soaked undercoating, but it took plenty of elbow grease. The reciprocating saw with a grout brush attached was the most efficient method of removing the softened undercoating, but it was all overhead work. We just don't see extra undercoating sprayed onto Texas cars, so we're not super experienced with its removal.

After a half day of scrubbing and some time spent with the pressure washer (again), real progress was made - and it showed us some important issues we needed to address.

The bottom of the floorpan was remarkably clean for a 37 year old car. The trunk area, floorpan, tunnel - all pretty clean now. This allowed us to see some sins that needed repair.

There was evidence of tearing at both transmission crossmember brackets that are spot welded to the floor, likely from a front end impact which was otherwise repaired fairly well. The above left pic (taken while cleaning) shows a gap along the top of both flanges. The above right pic (driver's side) shows another gap as well as a tear, plus some floor deformation that needed to be addressed.

We tagged in Christian at this point, as Brad was assembling the HPR built engine to the Tremec trans. He removed the interior to get the carpet out, as we had some welding to do underneath - and with any insulation or carpet above it, that just leads to fire. There was the stock carpet + jute insulation, another layer of some aftermarket insulation, and then the glued down asphalt OEM insulation inside that he removed from the front seat area.

The old carpet was disgustingly dirty and smells like a dirty sock, so I ordered new black carpets from LMR that day. Christian weighed 7.2 pounds of stuck on insulation that he removed just from the floor section, with a heat gun and scraper, and it came out relatively quickly. There's still more to remove on the tunnel and back seat area, but we'll tackle that later.

continued below

**Fair!** · 10-06-2025, 03:19 PM

continued from above

With the very clean floor we could see the damage and work it with a dolly and hammer. Christian straightened out slightly some bent sections of floor (drivers side, from above) moving the mating transmission mount brackets up to meet that.

He flattened the mounting faces of the brackets front to back, then a few holes were drilled to replicate popped spot welds with new rosette welds, and the MIG was used to stitch weld the seams as needed.

With those brackets bent back to the stock shapes and then stitch welded to the floor, he hit these areas with self-etching primer. We will likely paint the underside of the car when we respray the engine bay, but that's for later - now we can get back to building a new transmission crossmember to fit the TKX.

HPR BUILT 383" ENGINE ARRIVES

Skip this section if you care nothing about this GM LS engine - nobody will blame you. This was an engine built for another project a few years ago that was repurposed for this build back in June of 2025. This engine has a forged 4.0" stroke crank, forged rods, and forged Wiseco pistons with 3D milled pistons for a lighter total mass.

An aluminum block, with a spicy hydraulic roller cam (.643" total lift with 246/253 deg duration at .050" lift on a 110 deg centerline) and single pass CNC ported 241 cathedral port heads. Nothing crazy, more of a budget build that you could replicate for $6-8K.

This engine was originally built in 2020, used briefly in another car, and then put in storage. Before it was repurposed for this car it was disassembled, a few things were changed and then I picked it up only July 23, 2025 in my little Maverick. We quickly got to work putting this together as a complete engine.

The clutch and flywheel were robbed from yet another project with an LS swap - same car we took the Tremec TKX from, as that car is going to a ZF 8HP. We discussed using the 8-speed ZF automatic in the Fox, but the extra cost, complexity (tuning, adapters, wiring), size, and weight were deemed inappropriate for this build.

This Fidanza flywheel has been used in at least 3 cars in the past, going back to 2007 in our original BMW E36 LS swapped "Alpha" car. The steel mating surface still looks good and it still weighs the same 12.9 pounds that it did back then. Brad installed this to the crank with new ARP bolts and Loctite.

We used this ACT "GM9-SPSS" street performance clutch kit as well as the RAM Heavy Duty hydraulic throw out bearing kit with shims and alignment pin shown above, which are both suited for use with the "GM" splined Tremec TKX transmission. This is a heavier than stock clutch, but not by much - and attached to this fairly mild 383" LS it should be fine.

This full diameter, single disc clutch and pressure plate are hefty at 29.2 pounds. I was tempted to use a lighter, smaller diameter twin disc clutch and flywheel I had from another project, but I remembered how "not fun" that thing was to drive and went with the fill size, sprung hub ACT. This was bolted to the flywheel with more ARP bolts.

We of course checked the TOB depth and stand-off distance (.155-.200" to the pressure plate fingers, per RAMs spec) before we put the transmission on. This is the same bellhousing we have used on many TKX LS swaps paired up with a RAM TOB kit with custom lines we had in the other car. We added a remote bleeder and a quick connect to tie into the hydraulic master cylinder line. Brad then shimmed the TOB to get the right stand-off gap.

I rounded up the standard AC Delco starter we settled on years ago - it just works, is lighter than most, and it's new instead of rebuilt. The "early" LS7 water pump was bolted on, along with the thermostat housing, ICT Billet manually adjustable belt tensioner, and timing pointer. All we're missing here is the alternator and intake manifold, but it was time to bolt the complete engine to the Tremec transmission.

This weight was with our new "hanging scale" that makes drivetrain weight checks super easy. That engine tilter / chain setup weighs about what the plastic intake manifold does, so the 471 pound weight is still worthwhile.

And again the aluminum V8 is LIGHTER than the 2.3L that came out. All aluminum V8s are pretty amazing, and coupled with a light flywheel and 3D milled pistons it all adds up.

MAKING ENGINE MOUNTS

On the last day of July 2025 we were ready to finally install the completed engine into the little Fox, and it was time to dial in the drivetrain alignment and make some mounts.

With these completed engine + transmission installed, the drivetrain shimmed with wood again. Brad lined out the engine bay with strings to show centerline down the middle of the chassis, then a line between the struts to give us a fore-aft alignment marker.

We always shift any "V" engine away from the steering shaft towards the other side by 1/2" to 3/4" - as do most OEMs. It is VERY rare for a V6 or V8 engine to be dead centered in the chassis. The down angle on the back was more than I liked, but we would adjust that when we built the transmission crossmember.

The transmission is offset the same amount towards the passenger side as the engine, so it is parallel with the driveshaft and centerline. With the engine in place we also test fit the cast iron exhaust manifolds, which fit perfectly.

We had some block-side engine mounts from Holley we built around for this early stage, and decided to make some simple brackets that would be welded to the subframe on the bottom. Why weld them on? To save time - we're not trying to make an LS swap kit here, and this subframe isn't staying very long (two track tests, tops). Myles CNC cut and bent some pieces and the crew tack welded those in the car.

You can see the block-side mounts above, under the exhaust manifold. These were part of Holley's former LS swap catalog for the Fox that they have mostly abandoned due to many concerns and changes at the corporate level. Really wish we had some of those Hooker long tube header kits that worked with the stock crossmember, as I hate log manifolds - but again, this is just temporary.

With the engine out of the way, the new mounts were fully stitch welded, masked, primed, then painted in a matching white paint. It was super tempting to paint the whole engine bay at this point, but there is a lot of welding and clean up work (so many holes) that have to happen before we pretty it up in there.

DESIGN AND BUILD TKX CROSSMEMBER

Before you ask, yes we looked at what was out there to adapt the Tremec TKX transmission to the Fox chassis. We saw some crossmember designs but they were for the original SBF, and not the LS engine we are using. We also have some design parameters that somebody else likely doesn't share. So we're making our own crossmember for this swap - with this engine at this positioning.

Now that the chassis brackets are repaired and properly welded we can tie into those for a prototype crossmember. This crossmember could go into production, but it likely will get a revision before that point. Myles used another set of strings for reference and designed this in CAD using methods we have used on many previous transmission crossmember mounts we have made in the past.

The CNC cut main arms were mocked up in the car with the self-jigging components. Instead of having the big bushings at the chassis mounts, we incorporate a common Energy Suspensions poly mount at the transmission. The idea was to give the exhaust more ground clearance than the factory mount does, so the "humps" are taller than the OEM crossmember.

The basic design was tacked together in the car, and the driveline angles now matched our design goals. The assembly was removed and went to the fab bench to be final TIG welded and reinforced with some sheet metal sections.

Myles added these two panels with dimple die holes, then welded those in. The finished design was test fit, removed, and primed for a good stopping point on this design. It is bolted in the car and will get painted before we go to the track.

Overall we are happy with the design, and it ended up being lighter than the factory stamped steel unit and has a LOT more exhaust clearance. We noted one small change for a production part we will make, which I will talk about below.

LIGHTER CARPET AND INTERIOR

We keep saying - this is to be a real street car, but we also want to make it as light as possible. Why is that so important? Memories.

I remember my 1987 LX notch back that I raced through college as a 3050 pound street car, with an iron block & heads, and I think we can meet or beat that goal in 2025 with a lot better suspension, more power, better interior materials, and still have carpets. But we're still chasing pounds wherever we can find them.

When Christian tackled the floor pan repairs he pulled out the carpet and also scraped out 7.2 pounds of tar paper glued to the front seat area, but there was still more of this stuff to come out. After seeing the nasty stock carpet I ordered a new set of black aftermarket carpet from LMR, and that finally arrived so Brad tackled more tar paper insulation removal at the end of July.

The rear seat is practically useless in these cars. I sat in the back seat of too many Fox Mustangs in college, going to parties or dinner or whatever, because that's all my friends had. Literally nobody had a 4 door in my racing group of friends. I don't ever want to sit in that cramped back seat ever again - so it is coming out. We'll make some sort of "rear seat delete" kit with upholstery to cover up the sheet metal, and a firewall to the trunk, at some later date. For now, we removed the back seats (23.7) and factory jute insulation underneath (9.4) for a total 33.1 pound savings.

Brad spent the better part of a day with a heat gun, drywall putty knife scrapers, WD-40 and shop towels removing more tar paper and cleaning the adhesive, going into the trunk area (see below). Was it worth this work? Let's check the scales.

Brad ended up removing another 16.7 pounds of tar paper from the tunnel and back seat area, so that makes (16.7 tunnel and back seat + 7.2 from the front) a full 23.9 pounds of just tar paper insulation removed. Racers often remove this stuff to both save weight and to allow for clean sheet metal to weld to - for roll bars, roll cages, subframe connectors, etc. We'll have some combination of those safety and bracing options added to this chassis in the future, of course.

The factory carpet in this car is 37 years old and stanky, and it weighed in at 28.7 pounds with the factory jute insulation underneath. We're going without that jute, and the ACC aftermarket carpet came in at 8.8 pounds. Once we finish the seat bracket base design I'll show weights of the aftermarket seats vs the stock seats, then the new carpet will finally get installed. For now we're (28.7 - 8.8 lbs) 19.1 pounds ahead on carpet and 23.9 pounds lighter on tar paper and insulation, for a total savings of 43 pounds in the interior so far. I'll gladly take 43 pounds of weight savings while still keeping carpet and the rest of the plastic bits, we damn sure will.

CUSTOM CHARCOAL CANISTER

This is more "street car stuff", but done because the factory charcoal canister is long gone and we hate stinky race cars that smell like fuel. The stock tank needs to vent if pressure increases, and it needs to suck in air as fuel is consumed, otherwise it would suck in the tank closed.

The 37 year old system for trapping fuel vapors is long gone, so Jason showed me some off-the-shelf solutions, then came up with an idea he wanted to try - making one from a catch can and some charcoal pellets for a fish tank filter. I'm game, so we ordered both the tank and a huge bag of the charcoal, then took a look at the parts.

continued below

**Fair!** · 10-06-2025, 03:19 PM

continued from above

The imported aluminum catch can kit came with a lot of aluminum machined barb fittings, plus an internal screen that would keep the charcoal in the main chamber, and a bronze vent filter that will allow air to pass both ways. It also included an external vent filter, which we planned to place "outside of the car", and outside of the cabin. When the charcoal arrived on a weekend I took it all apart, configured it how I felt would work best, and added as much charcoal into the main chamber as it would hold.

We had the "big vent" in the fuel tank from Breeze, and that kit came with some appropriate fuel vent hose - which we plumbed from the top of the tank into the trunk. We just drilled a hole (see below left) to feed into our charcoal canister. That hose was shoved through a simple hole with a grommet, and had some slack as the tank was raised in place - should allow for tank removal without a bunch of hassles.

Normally I'm against plumbing through sheet metal without bulkhead connectors, but this is just a vent line - zero pressure - so we let it slide (literally). The restored fuel tank was raised in place and mounted with the stock straps and black abrasion shield, with the level sensor and wiring for the tank connected.

The external vent filter was installed in the "top" of the catch can at a 90 degree angle, and that was then mounted outside of the plastic fuel filler splash guard (see above left). The charcoal canister was plumbed at the bottom side (the chamber with the charcoal pellets) from the tank vent and Breeze check valve.

Brad then made a simple aluminum bracket that attaches to the trunk with a rivnut. That's it, that's the whole system. Less than $45 spent and it should keep the stink outside of the car (venting to the filter behind the fuel door flap, which isn't air tight) and allow the air inside the fuel tank to expand and contract without any damage to the tank.

HEATER CORE REPLACEMENT

Why show this step? Well to prove that we're building a real street car and not some dedicated race car. And also, heater cores were a common failure point for the Fox models when they were new. We're changing this one out suspecting it leaked - and if you could smell the carpet, you would agree. As soon as we saw the heater core out of the dash, it showed evidence of leaking.

The cooling system work we're going to perform would be pretty silly to then plumb into this old mangled heater core, with crushed hose nipples sticking past the firewall. This thing was chewed up and was begging for replacement with something fresh and better made.

We needed to drop the dash down anyway to tackle a hydraulic clutch system conversion, so we had this all aluminum heater core on hand to swap in. There was squirrel debris and other nastiness under the dash, so all of that was cleaned up.

The old heater core unit was brass and shaped exactly like the aluminum version (see above left), and the new one weighed half as much. Most OEMs have gone away from brass to aluminum for heater exchangers since the 1980s, and we're doing the same under the hood, too.

I replaced a leaky heater core in my Fox around 1992 or so, and I didn't have the patience to remove the dash - so like a hack, I just "cut a hole" in the HVAC box to gain access. I'm so glad we did this one the right way. This was a relatively easy one to check off the list, if you ignore the hassles of dropping the dash.

DESIGN AND BUILD DRIVESHAFT + SPEEDO ROUTING VER 1

It was August 2025 at this point and we needed to make a driveshaft to connect the Tremec TKX and the 8.8" axle out of a V8 Fox. The transmission crossmember had been painted with the same silver ceramic engine paint as the fuel tank, as you can see. I went through some of our "returned" driveshafts from our other swap kits to piece this one together.

In the past we sold swap driveshafts made to our drawings, designed for a specific chassis, transmission and axle for BMWs and other cars. Some people have reading comprehension problems and just order a driveshaft and hope it fits their random swap. We get so many angry returns from folks that we just stopped selling driveshafts last year - people cannot follow directions. That meant we had a few new ones leftover, and we robbed them for parts - including the front yoke and both machined aluminum ends for the U-joint connections. The TKX shares the same front yoke as the T56, that was installed it in the car (see above right).

We didn't have an original V8 Fox driveshaft to steal one from, so we ordered this axle flange yoke adapter for a 1350 U-joint from Denny's Driveshafts, then mounted that up. With those two ends complete, we could measure for the 3" tubular driveshaft and have that built to spec (made a drawing, spec sheet, PO, etc).

I went to a local driveshaft shop to have this made, and even using the aluminum yokes and all the supplies we offered up, and all they did was supply the main shaft + welding and balancing, wow they charged me a lot. But hey, it was done, and we aren't offering driveshafts for swaps ever again, so I don't need to worry about finding a new supplier with better prices.

This is when we went to put the stock speedometer cable into the TKX, which is setup to take a mechanical cable to drive the speedometer. We had ordered the "yellow" drive end to work with the 3.08:1 ratio rear end, and well... the prototype crossmember needed a bit of a tweak to line up. And later on, it needed more work still. We'll show that next time!

SECONDARY SENSORS FOR STOCK GAUGE FUNCTION

We're going to have a digital dash in this car, but it will be mounted off to the side - the main gauges I want to look at while driving on track are the original gauges from 1988!

These include the big 140 mph speedometer, the 8000 rpm tack, fuel level, oil pressure, coolant temp and voltage meter. To make all of those gauges function with the LS engine (which we're controlling with a Link ECU) we're running a parallel set of factory 1988 Mustang 2.3L sensors.

We could have pilfered the old sensors off the old 2.3L engine, but instead of re-using nearly four decade old sensors (and the oil pressure sensor was highly questionable) I splurged for new versions of the coolant temp and oil pressure. Jason found the right adapter for the M12-1.5 thread in the LS cylinder head to adapt the Ford temp sensor, and the oil pressure sensor will be tied into a remote hose and dual sensor package off the back of the LS block, with one going to the gauges and the other to the Link ECU.

Brad started thinning the factory engine bay harness to the bare essentials in September, including these two sensor circuits. The speedometer cable will still work, the tack signal will come from the Link, the fuel level circuit will go to the tank and the voltage is easy. The stock gauges will work in all of their 1980s glory!

RADIATOR AND FAN

When it comes to cooling, I've always been of the "overkill everything" mindset, and will take any small weight penalty that this brings. While we are focused heavily on weight, under-sizing the radiator or fan is not in my DNA. As we found out on our 800 hp LS powered S550 Mustang, you can have enough radiator cooling for track use at speed, but idling or driving slowly forces the need for a big electric fan.

After I took some measurements of the engine bay, I did my searches and ended up with the EXACT same radiator I picked for Trigger - it will also fit the Fox. That's great, because that thing is a BEAST. That also means that the same fan we use on the S550 - this S197 Mustang factory electric fan - will also fit. This combo solved my idling temp issues, and we can let the 454" LS idle all day in Texas summer heat now without issue. Coolant stays at 175-185F on track and cycles on the thermostat at 190F at idle in the paddock, with the fan going on and off as needed.

This Howe two-pass core was significantly taller than the "bolt in" aftermarket Fox radiators (most of which were $600-700) but we've got our tricks - namely, a slight radiator roll. I had hoped to push the top of the radiator under the stock radiator support (like we did in the S550) but the opening was too narrow to tip it forward, so we just pushed the bottom of the heat exchanger rearward and down a bit.

Without the massive mechanical fan and shroud the V8 Fox has, we have plenty of room. It helps that we pushed the LS as far back toward the firewall as we could. Lots of room. First, Brad drilled out the spot welds for the lower mounts, and those were removed to give us clearance. Then he added rivnuts at the lower portion of the front radiator support to hold some new "rolled" lower brackets. We used the same method and series of parts we have used many times before to mount radiators.

Brad made a pair of aluminum lower new brackets and added lower radiator mount bushings from a 1st gen Subaru BRZ, mounted inside these aluminum brackets. Those were then bolted in place at the lower radiator support with the rivnuts from above. This lets the bottom of the radiator slip down just about an inch.

Myles then machined some round aluminum stock on the lathe to fit these bushings, and he TIG welded those pins to the lower tanks, just like countless radiators factory are mounted. We did the exact same on the S550, and its worked well for 4 years. That gets the massive Howe radiator located at the bottom, with a tilt, so all we need to do now is locate the top.

Brad took some aluminum sheet, sheared that and bent it on a 90 degree angle. Some "clamp" mounts were built into this with foam cushions to hold the outside of the upper portion of both side tanks. This upper panel bolts to the upper radiator support on the Fox.

Of course the upper bracket is brush finished and has dimple die holes, because why not? The lower mounts are cushioned and the whole unit is supported at the tanks. We'll add front facing ducting panels to force the air from the grill through this radiator - later in the build.

This is how the finished radiator mount came out - it is a MASSIVE unit that the front fin areas see all of the front end airflow, thanks to the slight roll. We still have ample room in front of the engine, as you can see with the front accessories in place, above.

The S197 fan was mocked up a few weeks later, and of course it was weighed (9.7 lbs). It is a significant amperage draw, but we remove the 2-speed switch it comes with and run it wide open, with a trigger from the ECU through a relay.

It mounts exactly like the factory S197 Mustang fan mounts - with two bolted fasteners at the top and two slip in mounts at the bottom (with the two plastic lower fins). Brad made the little fin mounts and Myles welded those on, as well as some threaded aluminum bungs for the upper bolts. All TIG welded onto the tanks, and the fan fits perfectly with zero mods on this setup. If it ever dies, another $100 fan can be slipped in place and bolted down. Easy.

That's what the fan looks like bolted in, with some most of the cooling hoses in place - I'll show more of that next time.

WHAT'S NEXT?

This is a great place to stop, as this post is running long - but at least it got us into September 2025 work.

We're much further along and I will share more next time - hopefully with the engine running and the car moving under its own power again.

More soon,

Terry @ Vorshlag

**Fair!** · 01-05-2026, 02:27 PM

Project update for Jan 5, 2026 - The last few months have been super busy with this project as well as two other shop owned builds. But in late December we got the little 6.3L V8 running, test driven, and its already been delivered to the tuner - so I started writing this over the holidays.

Quick reminder - the V8 swap is NOT the focus of this build, just a means to an end. This car's purpose is to use for SUSPENSION DEVELOPMENT, which we haven't done any of yet. So if you hate LS engines just check back in in the Spring, when we have some better "baseline" track tests under our belt with this ~500 hp engine on the stock suspension and brakes. The 2.3L was such a boat anchor we couldn't use any of the track testing it barely managed.

The running LS swapped Fox is now actually LIGHTER than when it rolled in here with the 2.3L, which is amazing. I'll show the weights and updates below - Let's catch up!

RADIATOR, HEATER HOSES AND REMOTE RESERVOIR

We showed the Howe radiator last time, which we ordered as a cross-flow style - so the inlet and outlet nipples on the radiator are on the same side. This works out great for cooling efficiency and radiator hose routing.

When making custom radiator hoses there are a number of ways to do this. The way we have settled on and like is to measure and mark the nipple sizes of the water pump and radiator then we order aluminum tubing to make "joiners" for silicone hose bends of the appropriate sizes, with some of those being "adapter" bends of two sizes when things don't line up on the same diameter. I ordered these bends from various sources we have used in the past, and about a week later we had what we needed to start mocking up the hoses.

On Trigger (our 800 hp Time Attack S550 Mustang) above left we had a further distance and ended up with some longer aluminum runs on the main hoses - which ran right in the radiator exhaust wash inside the duct-box that was sealed to the hood. The first round of hoses on The Ocho (above right) was laid out, but it didn't fit well with the big S197 radiator fan we added...

With this longer 90 deg adapter hose we were able to route the upper hose around the DEEP electric fan with ample clearance. This allowed more room to reach in front of the engine, too. We use a bead roller on the aluminum tube joiners then stainless worm gear clamps at each junction. Could we use AN fittings and hoses? Sure, for about 5-10x the cost, with minimal reliability improvements. We've done this style on dozens of swaps and they prove reliable over 10+ years.

To plumb the coolant and heater hoses, we plan to use a remote (pressurized) coolant reservoir, which is not how Ford did it in the 1980s. We tend to use these welded Canton units. This was mounted on the passenger side fender well and we "T" off one of the heater hoses to feed this. The radiator cap is then here - in a higher spot of the engine bay than the radiator. We then cap off the radiator cap spot (or order a custom radiator without a neck) at the top of the radiator.

We looked at a lot of locations for the reservoir, and sometimes we're able to sneak it into the corner of the back of the engine bay, for the highest spot possible. That got super cramped on this Fox, so it went high up on the inner fender right in front of the passenger side strut tower. Once we decided on that spot, Brad made a cardboard mockup then an aluminum sheet bracket that is a simple: cut, brushed, bent, dimple died, drilled and riv-nutted setup. Yes this is over-the-top, but practically everything we're touching on this project is taken to the extremes - for reliability, durability, and some showing off.

One of the aspects that defines a street car is basic HVAC functions, like a heater / defroster. Now we won't be having air conditioning on this car right now, that is a possibility down the road so we left the evap core in the dash when we replaced the leaky stock heater core. I ordered 5/8" and 3/4" ID silicone bends and the same sized aluminum tubing and Brad got to work.

Brad routed these bent aluminum heater hose hard lines as close to the chassis as possible, for additional room to access spark plugs and later long tube headers (when we have a new crossmember that can fit those). The larger 3/4" hose is tapped into the bottom of the reservoir tank, to pull that to the coolant system.

One of the trick things that is hard to even see are the custom 3/4" and 5/8" heater line hold downs that Brad made, with hand tools and persistence. A friend pointed out on FB that you can buy such a thing for $30, but they aren't dual sizes like this. Again, some of this is just for demonstrating our capabilities.

Last up is this bent hard line for the steam vent system. We're tying into the top of the radiator (a bung with 1/8" NPT fitting), a "T" into the steam vent kit on the engine (which I will show in the intake section), and then it all terminates at the top of the coolant reservoir (another 1/8" NPT). Some "P" clamps hold it to the radiator top bracket. Clean, leak free, and durable setup with maximum clearance.

FUEL RAILS, INJECTORS AND INTAKE MANIFOLD CHOICE

This is a build that is made for a plastic OEM style intake, but there is always power to be made with the right choices here. I will admit that I spent WAY too much time looking at intake manifold options for this cathedral port LS cylinder head, mildly spicy 383" (6.3L) engine. We have built so many LS powered cars, and the basic rule of thumb is: For LS7 ports, the MSD Atomic 103 is best. For LS3 ports, those ports suck and nothing matters. And for cathedral, the FAST LSXR 102 intake rules the day.

A buddy recommend the LSXRT (T = Truck) intake, which has the same basic shape as the "R" but with a taller plenum. More plenum = more better, right? Well I found a Richard Holdner video that tested this theory on a similarly sized cathedral port LS and the LSXR. LSXRT, and MSD all made within ONE horsepower on an engine dyno. And I was very unsure if the LSXRT intake would fit...

So I punted and got the same LSXR intake we used on my C6, above left. That mild 6.0L LS2 with this same intake, a 103mm Nick Williams TB and long tubes, and a smaller camshaft made 440 whp - which really woke the car up over the stock intake and 90mm TB! We won't have the long tube headers on this Fox on the first dyno tune, which will choke down power until we get the tubular K-member and long tubes on - just felt it appropriate to share here what we can expect from the HPR 6.3L in this Fox.

Like the MSD and many other aftermarket LS intakes, the FAST unit is an assembly with port runners you can modify - and FAST even offers a couple of other lengths. We will keep the long runners in for now and might either 3D print a new shorter version or modify them for length, along with some dyno testing. But for now, the first thing you do with any of these intakes is take them apart...

These assemblies are always mis-matched at the port interfaces, and of course there is casting flash to clean up. This is the facts of life with ANY plastic intake, even OEM 1-piece units. We always spend about an hour or two with a sanding roll and smooth out these nasty ridges - smooth air flow doesn't like sharp edges and abrupt mis-matches.

I got some advice on what injectors would be appropriate for this engine and power goal, and a tuner I trust recommended these AC Delco 12607749 "flex fuel" injectors from 2009-14 Flex Fuel Silverados and Escalades. These are typically rated around 42-44 lb/hr or 440-470 cc/min, and as an experiment I bought a VERY inexpensive OEM replacement version ($75/set!)

These injectors have the very shortest (38mm) of GMs many LS injector lengths (LS7 length) and this cathedral port intake is made for LS2 length (53mm). So to go with the LS2 style fuel rail made for this intake (we really like the Deatschwerks unit with integrated billet brackets) we ordered some spacers from ICT Billet, using the injector spotters guide shown above.

Mounting the appropriate MAP sensor is important - the FAST is setup for 2 different locations (front or back), and but as you'll see below we were a bit tight to the Fox's firewall. We also picked Gen IV sensors (LS3/LS7) vs the earlier Gen III versions (LS1/2/6), because the crank is a 58x reluctor (not 24x) and we have Gen IV front cover and cam sensors, too.

We are also NOT using a MAF sensor, as almost nobody does with modern aftermarket EFI, and instead picks Speed Density style air-fuel management. We always buy an AC Delco branded MAP sensor, as this is critical and not worth saving "ones of dollars" on a knock-off.

I don't remember this being normal, but the FAST intake came with no gaskets (I know the MSDs do), but these are inexpensive to source and we added those + the injector spacers about a month after buying this intake in early October. Now we can finally get the intake bolted on (it had been mocked up many times). The 103mm Nick Williams DBW throttle body was also installed.

CYLINDER HEAD STEAM VENT PLUMBING

This is a uniquely LS engine thing, but the factory uses both 2 and 4 port "steam vents" for OEM LS manifolds. These tie into ports at the ends of the cylinder heads and remove a potential spot where steam pocket can form from the cooling system. These are then bled out to the coolant reservoir at the highest part of the cooling system. Our engine builder is adamant about using a 4-port system, and no the LS truck hard OEM 4-port line kits don't fit under the MSD or FAST intakes.

We have spent more time chasing a "good" 4-port steam vent kit than I care to admit, with purchases from 5 different suppliers - and we usually have to modify them anyway. And when the leak, esp. at the back, it is nearly impossible to see... and that makes for a coolant system that never gets up above atmospheric, which is a problem. I did more research this time and found one on eBay for about $200 that had all of the -4 AN hoses terminated and was supposed to fit the FAST intake. Ones for the MSD are very different, as the shape of the intake dictates this.

The kit being from an eBay seller means there are zero instructions. Brad tried a few configurations and only changed one line for our setup - the one that goes to the "T" at the radiator, shown above right. Zero hose clamps, this is all 100% AN fittings and braided lines. We know now, after many attempts at this, to look at the 4 landing spots on the heads for leaks, too. So far this one has been rock solid.

FRONT ENGINE ACCESSORIES AND BELT

After 25 years or racing and building LS powered cars I could write a freagin BOOK on the many different ways to lay out the front drive accessories and belt routing. Most of the cars we have been building for the last 10 years do NOT use a power steering pump, and that complicates things up through the C6 Corvette, as GM didn't go to an EPAS steering rack until the C7 (2014).

We're not using hydraulic Power Steering on this Fox because, you know, its the 21st Century Fox - and high pressure hydraulic fluid is the #1 cause of underhood fires. We'll suffer through the first couple of track tests with manual steering, then add an EPAS column to the car later.

The early "PS Delete" routing we used (above left) was something we nicked off of drag racers online, and it has TERRIBLE belt wrap at the Water Pump pulley. Ideally you get 180 degrees of belt wrap or more (but 90 deg works on the WP pulley), and that setup had like 45 degrees at the WP. The new setup we use includes ICT Billet PS delete kit (above right) and a manual belt tensioner from the same supplier. This gives about twice the belt wrap at the WP, which works. We have done this on a few cars and it has been flawless with no chewed up or jumped belts.

I like the "tightest to the block" accessories spacing depth from the Corvette / G8 / CTSV. And we always try to use the Pontiac G8 alternator and bracket. It has an extra boss on the back (more stable), and it mounts low and tight to the block. The C5/C6 Corvette alternator is in outer space, waaaay up there. The bracket was hard to source - so we took one off another car, 3D scanned it, and got ready to machine one. Then found the last one in the country and saved a bunch of effort.

For water pumps we like the "early" C6 Z06 7.0L pump, as it puts the top nipple on the passenger side just above the thermostat, and that works better for dual pass radiators with the nipples both on that side. Once we had everything bolted up we used a string to check belt length, and it matched the same belt length we have used on many others: I ordered a Goodyear 6-Rib, 77.0" in length p/n 1060770, and it worked perfectly.

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**Fair!** · 01-05-2026, 02:52 PM

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EXHAUST SYSTEM FAB VER 1

This is a temporary setup that will change in the future, for two reasons - 1: We will add long tube headers, so the front will change. 2: Once we tackle the IRS rear suspension we will leave room for a full tailpipe layout. That is why we did the quick and dirty setup using Flowmasters with dumps - just like I had in college! (*note - I'm not proud of that)

I haven't used these mufflers in at least 30 years, and I never weighed one. Without the normal packing, the Series 40 in 3" in/out is only 9.6 pounds. And as you will see below, is one of the few that fits the Fox in the smallish space for mufflers under the back seats (double offset on the inlet and exit).

We almost never use off-the-shelf exhaust systems because the fit and layout usually stinks. What we like to do on anything custom is get the headers/manifolds in place, then the driveshaft of course, then mock up the mufflers at the back. Again, the tight confines on the Fox chassis limit muffler position, and the fuel tank placement means no rear muffler case of any decent size will ever fit behind the axle.

Obviously the log manifolds we were forced to use with the stock crossmember aren't known for adding power, and these have an outlet that is a smaller flange opening that I had hoped. But we went ahead and made a dual 3" dia mandrel bent system, to minimize the losses behind the logs. The layout of our TKX specific crossmember has plenty of room but the speedo cable routing was in the way - more on that below. We got the first pieces tacked together from short bends and it was time to join the front to the back...

The exhaust clearance on this dual 3" setup is better than any Fox exhaust on the previous 7 versions of this chassis I have owned. Christian followed the tunnel and tucked the exhaust in above the frame and floor everywhere - so it won't be dragging anything, no matter how low we run the ride height.

This system was built over a two day period and probably gobbled up 10 or so hours, which is pretty good for a 100% mandrel bent, fully TIG welded, stainless steel, dual 3" diameter system. Not having the "over-the-axle" or tail pipe sections saved time, of course. The dumps are aimed away from the axle pumpkin, and are no where near the fuel tank. Not my first Fox with dumps.

We added proper exhaust hangers at the back and then Christian smoke tested the whole system to find any leaks. One small re-weld and it was ready for final installation. We had added weld-in O2 bungs on both sides, as the Link ECU would use a dual lamda wideband O2 sensors.

I was very happy with the fit and the weight. This system is made of 409 stainless, not the 304 we formerly used on all custom builds. I've found over time that when we add the "ceramic coat + polish" finish to the exhaust (which we always do - and will here, after the long tubes and new rear section) it looks and performs the same as if we coated a more pricey 304 system - and 409 costs a whopping 48% less than 304 from the same source! I will put a video at the end - yes, it sounds ROWDY.

FUEL SYSTEM PARTS AND PLUMBING

With the exhaust system built, it came right off so we could route a new fuel system. After looking at the stock fuel system to evaluate if it can work for the V8 engine, of course this Fox's wimpy lines were not up to the task. We wanted to plan for at least 500 whp, so that means: new fuel lines with 1/2" (-8AN) lines. Since we prefer to run a return style system, that means two 1/2" lines for feed and return.

We ordered this Deatschwerks fuel pressure regulator and manual gauge , plus some ORB to AN fittings. All of this is mounted in the engine bay using the DW bracket. This company makes some great stuff and they are close to us in Oklahoma City (we are in Dallas), and their fuel rails are second to none. They also make injectors, fittings, filters, and more.

The main long runs from the tank to the engine bay are made with these 1/2" aluminum hard lines. These come in round coils, but we use a tubing straightener (see above left) to get those sections strait. The bends are made with various bending tools and the ends where they meet AN flex lines are done with flares and ferules.

We prefer to run the hard lines under the floor, but above the lowest parts of the chassis. Some folks like fuel lines in the cabin, but we avoid that in almost every situation. I'd rather have a hard line snagged during a huge off than a leaking hose inside the cabin. Brad wrapped the two hard lines in rubber hose as he passed them through a round opening (one was stock, the other he opened up) in the transmission crossmember brackets.

As an engineer that designed oilfield equipment that was made for the harshest environments in the world, I learned a lot from the actual techs who built what I designed in the shop next to the engineering headquarters at Baker Hughes. They were vigilant in their use of bulkhead connectors when switching from hard to soft lines, or any time important fluid lines passed through sheet metal. It stuck with me and we always make these little bulkhead brackets when switching from hard to soft lines, like at the base of the engine bay (above right).

As an engineer that actually bothered to check on his projects during construction, and because I was a gear head, they also reinforced the importance of leaving room for maintenance access. Notice the deep socket on the upper control arm bolt in the top left picture? Brad knows this too, and routed the lines around the socket for future access. We used Fragola fittings and hose ends almost exclusively on this system - we buy a LOT of items from F-K / Fragola each year, so our pricing is great on these extremely high quality, US made parts. I'd put Fragola up against any brand.

We never want to run volatile fluids next to heat sources. And the purpose of a muffler is to turn noise into heat, so where the lines run next to a muffler Brad built a stainless steel heat shield, with air gaps to the lines and the muffler. Stainless steel has lousy heat transfer properties, so it makes for a good thermal barrier material.

For an extra measure of safety, we also added a layer of DEI heat shielding on the muffler side. The flex lines back here are wrapped in DEI fire sleeve, but more for abrasion resistance near the steel fuel tank than for heat with this short (dumped) exhaust.

We utilized a Radium Engineering 10 micron fuel filter and mount at the rear, and the -8 flex lines go to the fuel tank from there. Up front, the mini bulkhead is where the hard lines go to soft and up into the engine way. Lots of room was made from the lines to the exhaust manifolds, of course.

In the engine bay, one -8 line ends up going to the DW fuel rails and feeding that system then to the regulator, where the return line goes back to the tank as the whole pressured system is dropped to 45 psi. No corner was cut, and the double -8 system is probably good to 600 hp. With top quality parts and labor like this, with this level of detail, this is a $4000+ fuel system for a normal customer. Good thing I'm the owner and can conspicuously ignore this enormous amount!

EPAS RACK TESTING?

One of the many goals of our 21st Century Fox project line is to use modern everything: ABS brakes, EPAS electric steering, Traction Control, and modern hubs + suspension + calipers. I talked about our aversion to hydraulic power steering above, and our first test to solve this in the Fox was to test fit an RX8 EPAS rack.

You can get one of these used for about $200, and after some initial measurements it looked good. We weighed it - almost 32 pounds! The electric motor is inside the main section of the rack, unlike modern S197/S550 EPAS, which are beside the rack...

We measured the main distances for the mounting holes (2" off) and the pivot points at the inner tie rods (which were within 3/4"). This was pretty close on the pivots, and we could alter the outer tie rods to work. So we next mocked it up...

Well - long story short the GIRTH of this EPAS rack is simply too big to clear the stock crossmember, almost any oil pan, the stock swaybar, and it is a bust. Compared to the tiny Fox rack, which is petite and fits everything. We will test this again once the stock crossmember is gone, but more than likely we will can just convert the Fox rack to manual and put the EPAS assist in the steering column. A $200 gamble - that might work later.

HYDRAULIC CLUTCH CONVERSION

One of worst failings in the Fox was the "self adjusting" plastic clutch quadrant and cable operated clutch arm. I had failures of both the cable and quadrant in multiple Foxes back in the day, but just upgrading to a metal quadrant and adjustable length cable wasn't good enough for our 21st Century Fox.

We almost went with a store bought hydraulic conversion solution, but the setup we came up with uses a better master cylinder than any of the kits out there. It was harder to implement than I had hoped, and we will see if this is the right solution to release to the world.

The Tilton 78 series master is a great unit and we wanted to use that for various reasons. It has an integrated spherical at the end to make mounting easier (and deals with misalignment). We also sourced clevis ends and pins and I found a small aluminum fluid reservoir for using in this system, since the master will be mounted under the dash without good access to fill fluid.

Jason's idea was to replace the plastic clutch cable quadrant with an aftermarket aluminum one, and have that push the Tilton master. We rounded up a generic aluminum quadrant and drew up the mount for the master.

Calculations were done but we drilled a number of mounting holes for the clevis mount in the aluminum quadrant, in case the motion ratio was off. A couple of iterations of the "U" shaped bracket were built and the final one is shown above. There is a small amount of trimming on the pedal box - a flange is trimmed on the side next to this bracket, to make room to clear the clevis motion. This has to be done out of the car, and removing the pedal assembly is "fun".

The video linked above above shows how the final setup works, and this was bolted in and "finished" in August. Next it was time to plan all of the plumbing, order the parts, and even have crimped -3 AN lines made to order.

By September we had the custom crimped hydraulic lines from Fragola along with some hard line and fittings. Brad got to work connecting all of the lines to the master and slave, including the line that goes through the transmission tunnel (bulkhead connector) and connects with the RAM HD hydraulic clutch slave cylinder inside the Tremec.

The images above were taken in 2020 when this Tremec TKX and the ACT clutch were in a BMW endurance race car project with a 5.3L LS, which that has now gone another direction (my S65 + DCT swapped E46 race car for 2026). We stole the TKX, bellhousing, clutch, flywheel, and RAM HD clutch slave / TOB from this E46 and used it all in the Fox. Only the line we made for the BMW master was changed, otherwise it was all just re-used here.

My little hydraulic fluid reservoir needed a Schreader valve added to allow for volume change, then Brad made a bracket to mount that to the firewall. He then added a bulkhead connector and hard line to connect to the inside. The bleeder hose end from the clutch slave is zip-tied in the engine compartment, to make it easier to find when we need to bleed the clutch. The clutch worked perfectly on my test drive, and we will make an adjustable clutch pedal stop before the car goes on track.

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**Fair!** · 01-05-2026, 03:13 PM

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SPEEDOMETER CABLE CONVERSION

As shown in the exhaust fab section, the factory speedo cable goes into the TKX at just the worst spot possible for the extra exhaust ground clearance we wanted. Instead of redesigning the crossmember and exhaust and making both worse, we went for a novel solution that Jason dreamed up. He knew of a 90 deg speed adapter, which I ordered, along with a custom length cable with "Ford" on one end and "GM" on the other.

Several parts orders later and we were able to mock up the 90 deg fitting and it cleared the crossmember. Brad hooked this all up in the transmission and routed it into the passenger cabin.

Took a few mock ups but Brad got the cable clocked, routed, attached to the back of the stock speedometer - and I'll be damned, it worked! I checked it against GPS and it was spot on with the correct (color coded) drive gear at the transmission.

CRANKCASE VENT, CATCH CAN AND PLUMBING

In late September the engine bay was starting to fill up, but we had a vented crankcase oil catch can to add. We put these on ALL tracked LS V8s, as these engines have a tendency to have positive crankcase pressure and pump oil out of every orifice - so we give that a place to vent and also catch any liquid oil that is pushed out.

We have used this Peterson Oil Systems "08-0400" vented catch can on many race cars going back for 15+ years. This dual inlet version works well to vent a wet sump LS V8 from both valve covers. One vent hose isn't adequate for a wet sump (it is for a dry sump) and we run LARGE diameter -12 AN hoses for this purpose. The goal is to place the catch can higher than the engine, so the lines run uphill - this keeps most of the liquid oil from actually entering the catch can.

This pair of ridiculous cast aluminum valve covers with the "CHEVROLET" lettering was abandoned from a customer's project long ago. They are slightly taller than stock, but don't have provisions for for the coil mounting. This makes coil mounting a huge hassle. In 2020 I had these powder coated red, then our crew drilled one of them for a big NPT fitting.

The fitting had to be shortened, as it stuck through the valve cover and would have interfered with a rocker arm. We also drilled and tapped the other cover for this Fox's dual vent hose setup in 2025. We screwed an NPT -to - AN-12 fitting, and placed a Nylon gasket at the face of both valve covers to seal that.

After mocking up the catch can and clocking it to clear the strut tower and firewall we needed a 90 deg and 120 deg -12 AN hose end fittings. Brad built the Fragola hoses to go from both valve covers to the vented catch can. The hose from the pass side valve cover loops to the front, but that's because a direct routed hoses was too short to take up any engine movement and still connect at both ends.

This setup should work fine for our Fox, but it is a vented can. This car being more than 25 years old gives us a little leeway, but state emissions laws might frown on a vented catch can for your build. We built a "sealed" EGR style catch can in this forum post for another LS. It is a good bit more work, but squeaky clean legal.

SECONDARY (OEM) ENGINE SENSORS

We touched on this in the last update, where I ordered a new set of OEM sensors for a 1988 Fox with a 2.3L engine - that way the stock Fox gauge cluster is setup for the same sensors and just works. We didn't have much to source here - oil pressure and coolant temp.

Last time I showed the temp gauge installed in the second cylinder head, with an adapter. And then an adapter for the oil pressure tap at the back of the LS block. We set that up to have a remote hose and ordered this -4 AN x 12" long hose from Fragola, already crimped. Ask a good tuner and they always want to see pressure sensors isolated and remote mounted, for better data.

What you see above is a RIFE 0-150 psi sensor that will feed the Link ECU, off an adapter that has an 1/8" NPT fitting. Onto the end of that goes the bulbous Ford pressure sensor, which goes to the stock gauges. Brad built a bracket that attaches to the firewall and holds this whole stack of sensors.

It looks like a sizable chunk and it is - but the bracket for both hangs off the flange at the firewall. The 12" long hose curls down to the adapter at the back of the LS block and I am happy to report that both the Link screen and stock gauges worked perfectly.

This way we can get on track without spending $1800+ on a digital dash just yet, and just watch at the stock gauges. We do have a lower cost digital dash we could add, but it's not our normal AiM system, and lacks AiM's built in Predictive Lap Timing. I am still mulling over the idea of using this lower end digital dash in the Fox.

ENGINE BAY WIRING CLEANUP

In mid-September it was time to start thinning out the stock engine bay wiring harness. We knew at this point what circuits we needed to keep and which could go away. The Link ECU was going to drive everything in the engine, but we kept the lights, wipers, and stock gauge circuits.

There is no short cut here - you can remove as little or as much as you are comfortable doing. We do this on lots of cars and it is STILL a chore. We had a Factory 1988 Ford Maintenance manual, but it had almost none of the 4 cylinder schematics, so Brad found this one below and it proved helpful.

I hate an ugly engine bay, and nobody likes wiring gremlins. There was some non-stock wiring around the stereo and some weird switch under the dash, but Brad surgically removed all of that. He also took copious notes on the wiring he added for the Link, the CarTek battery kill, and the taps into the ignition switch / starter and alternator.

That's my best advice - keep good notes, and transfer them to a Google Doc or something that is impossible to lose.

STRUT TOWER BRACE

I debated not adding a 3-point strut tower brace at this point, but we had a lot of things going on under the hood and I wanted to save room for this super popular and necessary upgrade (for a Floppy Fox). Better get one and mock it up in the car, at least. Will this affect baseline lap times? I doubt it would with the original soft suspension, but it cannot hurt in this dated chassis.

I picked up this BBK 3-point brace that attaches at the firewall. Wow, this got some folks riled up when I showed this on FB - "oh you got the firewall flexer!" Well sometimes you just have to tune the haters out. It fit around everything we had in the engine bay and we decided to just go ahead and drill + bolt it in. It came in and out a few times but was bolted down after we were sure the engine didn't need to come back out.

Right after our first track test we are coming back to the shop to design and install new Fox camber plates, and we need to make sure they clear the popular 3-point brace - like this one. The firewall plate was a bit "off" and we had to re-drill the hole in the firewall that is made for the windshield washer hose pass-thru. Brad shot a little white paint on some crusty bits, too.

After seeing it installed I'm glad we did this little upgrade now rather than later, as it helped set locations of a number of things we added right after this.

NOCO 5 POUND BATTERY + BRACKET

I could write pages about batteries, the trials and tribulations we've had with tiny AGMs, "O" branded full sized AGMs, wet cells, and this latest craze - Lithium Iron Sulfate batteries (LiFePO4), specifically from the company NOCO. I don't sell these things, and I am hesitant to change battery brands or styles, but I jumped into the NOCO world more than a year ago and have them in 4 cars now with great success.

After about 2020 we had absolute sh1t luck with the two brands above - at this point you couldn't PAY me to run either brand's battery. Have used countless Odyssey power sports batteries in the past, as well as full sized Optimas, but longevity and reliability went to complete crap after the Pandemic. I cannot explain why, but this is over dozens of data points and I hear the same form almost every shop owner.

Above is the NOCO NLP20 at left (sub 4 pounds, $179, 600 amps) and NLP 30 at right (5 pounds, $199, 700 amps). The costs and the stats are circa late 2025. We used the NLP20 in our 1995 M3 for a season and yes, if it sits for more than a few days it wants to bleed down. So we just keep a battery tender on that car in the shop. We picked the NLP30 for the Fox, as it has a bit more oomph. We were able to start the V8 a dozen times before we got the car fired up without needing a charger.

Keeping the battery under hood saves money and weight - we don't need pricey, heavy, 00 gauge stranded cables running to the trunk. That also removes some voltage drop over long distances. We put this in the right front corner of the engine bay and built a (fancy) bracket to hold it in place.

Brad likes to make really elaborate aluminum brackets, but they always look and function amazingly well. Normally he'd make a cardboard template, I'd scan that, we'd turn it into a .DXF in CAD, then CNC cut the parts on the plasma table. But he made this when both engineers with CAD access were on vacation, so he cut this all out by hand. Tedious, for sure, but it looks and works great.

After mocking up the design he added a dimple die, brush finished the raw aluminum, and bolted it into a factory fender liner hole at the top. We decided not to use the typical SAE style terminals and clamps and just went with bolted ends for the cables. I'll show that wiring work in the CarTek battery isolator section.

REMOTE IGNITION COIL MOUNTING

Remote mounting the eight ignition coils is only nominally about performance or reliability. It is mostly about showing off silly valve covers and for "style points". Having to make custom length spark plug wires is a lot more work than it is worth, however, so I caution anyone who wants to do this. I will share the plug wires we like, after testing out 4 different brands on Trigger.

The LS family of engines has too many different coil shapes, just like it has too many injector height styles. The round style above left is what we used on Trigger, my 454" LS powered S550. On the Fox here I wanted a flashier set, and these square style red LS coils from ZZ Performance at $199 were hard to pass up.

We had a set of ICT Billet remote coil "gang mount" brackets but the ends looked a bit Agricultural, so Brad hand made new brackets to fit a unique placement. The brackets he made looked 10x better and got a brushed finish.

We debated a half dozen mounting locations but settled on a setup next to the fuel rails. Brad made some aluminum angle to run next to the rails and some threaded blocks to mount the modified ICT gang brackets to.

Oh yes, daddy like! I was very happy with the finished brackets and locations and we just needed to attack the plug wires at a later date. "If you can't go fast - look good!"

In late October on a weekend when I was at the shop (like most weekends), I rummaged through the parts shelf for Trigger and found FOUR extra sets of plug wires we built for that car, not including the 5th set we have on there now from Katech. I checked my notes and the best setup we used was an MSD kit that we made two sets of, and I pieced together 8 wires for the Fox's setup - and they all work, thankfully. Plus we have lots of spares.

BATTERY CABLES, CARTEK, AND CIRCUIT BREAKERS

It is the middle of November and the end is in sight - all we need to get this engine started is the Link ECU and a bit of wiring. In this section we'll talk about the main battery cables for starter, power supply, alternator, and dash. We'll also tackle the CAR TEK battery isolator work and circuit breakers.

Making big battery cables isn't hard but there are some tools that help. To cut the big 00 gauge stranded cable a big set of bolt cutters is your friend. The main wiring goes from the battery to the starter, to the dash, and to a power distribution point on a panel next to the NOCO battery. We have a big crimper we use for the ends, which is an impact style you whack with a big hammer.

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**Fair!** · 01-05-2026, 03:45 PM

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There is a #4 cable that goes to the alternator and another #4 that goes to the factory fuse box, which is under the dash. These longer runs were routed to keep the cables away from heat and chafing dangers.

Brad made this aluminum panel to mount he CarTek and a 50 amp circuit breaker, which feeds the Link ECU system. We left room for another breaker or two that will feed the EPAS steering and ABS units later, both of which can have a high amp draw. I am not a huge fan of PDM modules, as those become a known failure point that can shut down a track weekend in a hurry if they go kaput. They also don't save almost any weight and cost $1000-2000+

The bottom of this panel has another insulated power post that the #4 cables come off of, and again, we left plenty of room for another pair of breakers for use at a later date.

There was also an auxiliary circuit panel with fuses and relays that Link suggested we buy, and it did come in handy. This was wired to a the electric fan circuit, fuel pumps, and some other items the Link controls. It mounts to the firewall as shown above. Brad spent a couple of days wiring all of this cleanly, but its necessary work.

In December when it was time to fire up the engine the two CarTek buttons were wired in - one in each speaker grill. This worked out nicely for access and ease of replacement of panels, if we do ever put a dedicated switch panel in the center stack. Honestly I like having access to the battery kill on both sides near the door windows, in case a corner worker needs to shut down the electrical system in a hurry (we will add the lightning bolt decals).

DBW GAS PEDAL

Whenever we build an older car to use a more modern engine we always try to go with a Drive By Wire (DBW) pedal sensor from a similar car as the engine itself. This helps with tuning and traction control as well. In the case of LS engines we use the C6 LS3/LS7 pedal or the CTS-V pedal, depending on the route the pedal arm needs to go and other firewall considerations.

We keep both on hand for swaps and in this case the CTS-V pedal was the right configuration. We can unbolt the side-mounted bracket these come with and make something new with a flange that fits the firewall.

Myles made this cardboard template then turned that that into a bracket that was hand made. If we get enough interest we can make a CNC run of these brackets, but it isn't rocket surgery here.

Getting the gas to brake pedal spacing is very important, especially when the brake pedal is depressed (for better heel-toe placement - laterally and through travel). This is more important than words can describe, but it felt good on my test drive and I'll verify this on track soon.

LINK ECU + LS HARNESS

After some fits and starts with other brands of EFI systems (Holley, Haltech, Motec, HP Tuners, EcuTek, etc) we chose the Link ECU stand-alone G4X system and the Link supplied LS engine harness. This is our 3rd Link EFI system in 2 years and we've got a great contact at the National level that lives down the road from the shop. George has been invaluable to getting us going with Link systems.

The main harness is configured for either Gen III or Gen IV sensors, and they use DT connectors to small adapter harnesses for the sensor ends, to give you flexibility to choose. We also got the mini aux fuse and relay panel and dual Lambda (wideband O2) sensors that connect via CAN.

We ordered these parts and received them in September, but actually started the install in October. The only engine wiring missing was the coil harnesses shown above, but these are easy to source, and plugged right in. We found a slightly longer set of LS coil harnesses for our remote coils, too.

The engine harness plugged into the various sensors and sub-harnesses and just worked perfectly. Brad mounted the G4X ECU close to where the stock Ford computer mounts, in the right front kick panel. We left it a little more visible, as we need to access some comm ports and to see some status LEDs during startup testing - which we stumbled a bit with, but with Link ECU's tech help we got it fired up.

PARTIAL PROGRESS WEIGHT CHECK

On December 1st, 2025 the Fox was far enough along for a weight check - as we weighed two other cars the same day. This was shockingly low and got me pretty excited!

The dash was sitting on the car, and the entire drivetrain, exhaust, brakes, and wheels were installed - just no hood, seats or fluids. We started at 2810 pounds with the 4 cylinder so this 2536 pound weight gave me hope (which was later adjusted back to reality).

LIGHTWEIGHT CARPET INSTALL

In the last post I showed extensive interior insulation removal work (to reduce weight) as well as weights of the stinky stock carpet (28.7 lbs) versus a new ACC replacement (8.8 lbs). Now in early December 2025, after wiring and plumbing inside was wrapped up, we were finally getting ready to install it. Warning: This is cheap carpet and it doesn't fit like OEM molded heavy duty stuff. We wanted lighter, and the "not quite OEM" fit was part of the deal.

Following the instructions from ACC, the OEM carpet was laid on top of the new carpet and various cutout holes were marked. Brad cut the big holes along the tunnel for the shifter and E-brake, but the smaller holes for seat and belt mounting were not - because the fit of the new carpet just wasn't that spot on.

The carpet was laid inside and it was quite lumpy - normally you place this outside in the sun, let it warm up, and the wrinkles calm down a bit. But it was unseasonably cold here, so it was put into the chassis and four 45 pound flat weights were placed in the floor to hold it down and help it take shape for a few days. That mostly worked, and Brad worked on fine tuning the shifter and e-brake openings.

Once I realized we would never reinstall a back seat into this car (I wouldn't wish that cramped seating on anyone) we removed the rear seat belts and hardware, lopping off another 4 pounds. We left the carpets to "rest" with the weights for a bit longer while the rest of the dash wiring was completed.

DASH WEIGHTS AND REINSTALL

Keeping this car light is a very high goal, but we also have to keep this as a believable street car - unlike almost any other race car build in the Vorshlag shop in 2025. I really do want to be able to hop into this Fox, drive it across town, and not cringe looking at every pebble in the road.

I weighed the dash and various bits a few different ways, but the 15 pound stock dash plastics and vents were lighter than most. Of course all of this was cleaned up before it went back in, with 40 years of muck was removed from all surfaces.

The grey dash cleaned up well but the air vents were all sun faded quite a bit - almost tan in color. The clear plastic lens on the main dash cluster was hazy but Brad polished that with cleaner wax and it looks like new. LMR sells all of this stuff, of course.

We noticed a busted ribbon cable on the back of the gauge cluster and Brad fixed that with a soldered jumper wire. Then Brad spent the better part of a day fighting the dash, getting it reinstalled correctly.

With the main dash plastics in, the rest of the interior fell into place. The gauge cluster was connected, as was the speedo cable. Then the surrounding binnacle, then the center console base - which was in great shape once cleaned up.

The upper plastics of the center console were badly faded, almost tan again. The arm rest was a bit busted up, but I have a solution for both. The plastics around the right kick panel were modified to fit tightly to the Link ECU.

Working out in the shop one day I found the stock handle from the 2.3L's transmission and found that it has the right position and bolt spacing for the Tremec TKX. But the hole sizes are off, so I found that some longer M8 bolts that worked, and thru-bolted that to the TKX's shifter stub. That weekend I also worked on installing the front seat belts and seats - marking and cutting holes for the various hardware (it took over 3 hours - total PITA).

With both seats installed I could get some pictures of the interior, which turned out pretty good considering how long this car sat outside in its 38 years of life. The black carpets looked better than the stained gray bits, and I was glad I went with this color - and while cheap fitting, the ACC carpets were at least very light and one color.

I have since ordered a few things to solve some issues inside. The 6000 rpm tach isn't appropriate for this LS engine, which is safe to 7500 rpm and will likely make peak power at 6500+. I'll at least get a stock 7000 rpm tach and replace that after right dyno tuning. I also found a nicer center console with cup holders (in lieu of an ash tray) and an armrest delete, which will both replace faded or busted bits. And of course the classic white Hurst 5-speed knob has to go in.

FLUIDS, START UP TUNE AND TESTING

The day after the "progress" weight above, fluids were added for the engine, transmission, and clutch systems. We used Motul 8100 5W40 in the engine and ATF VI in the TKX trans.

Five gallons of 93 octane fuel went into the tank and Motul RBF 600 went into the clutch system, and then it was bled.

Before the dash went in there were some initial tests - key on, check fuel pressure, fix any leaks. The ignition switch was tested and looked a bit melty, but it worked fine. We will keep an eye on this but it is fully functional. Cranking tests without fuel or spark to check oil pressure.

We're going through the start up test lists and had a start-up base map then we began bumping the starter, checking injectors, checking for spark. Coolant system was pressure tested, fan relays were triggered, and sensors were calibrated for the Link ECU software.

One omission from the Link supplied LS harness was the lack of a throttle pedal connector. We were told they just don't supply that, so we looked up the 6 wire diagram from the interwebs, sourced the connector, and Brad got that wired in then tested. Now we were ready to start the engine up, for real.

We are not a tuning shop and this was the first time using a Link on an LS - the Link "plug in" system we installed on the E36 M3 had an excellent base map for a stock S50, and it fired right up. But on this LS engine there are so many variables and this engine was anything but stock. Christian found the right injector information but that was about it. We cranked the starter and it wanted to start - we fought it for a couple of days, off and on.

George from Link ECU stopped by and helped us work with their tech support folks and they made some big breakthroughs - and the above right video is the 6.3L idling on December 17th, and it sounds good! Throttle response is garbage, but that's something for the tuner to figure out!

continued below

**Fair!** · 01-05-2026, 03:52 PM

continued from above

COLD AIR FILTER BOX

The day after the engine was fired up and running right, it was time to tackle some testing. We also needed the cold air box complete before it went in for a dyno tune. We're using a massive 4.5" ID tube with a 4" (103mm) throttle body, and a 4" to 4.5" adapter 90 deg silicone hose bend (yes, its ugly and blue, but its what we had on hand). At the end is a huge pleated / washable filter with a 4.5" inlet, but we don't want that sucking on hot air from behind the radiator.

The holidays were creeping up fast so I asked Brad to tackle this before his upcoming 2 week vacation. He has built a number of these air boxes and the first step is always the cardboard template. We looked at attachment points and how to bend / build this one.

Brad ended up making this from two pieces of .063" thick aluminum sheet, hand cutting everything. There is a lot of fiddly work involved in this, and it takes time. The cold air for the filter comes from behind the headlight and around the radiator from the grill. When we have more time we will come back and block off the opening on the "U" section above the 4.5" tube - and we will add more DEI gold foil to the airbox, like the main intake tube has now (this was another cast off from Trigger).

The top of the box is shaped to seal to the underside of the hood, but we ran out of the rubber weatherstrip seal. I ordered a 10' roll that arrived long after the holiday vacations began. This is air box about 80% complete but, good enough for dyno testing (they dyno test with the hood open, anyway).

WEIGHT + TEST DRIVE

On the weekend after this last push of work I tackled a few more after-hours tasks so I could take a test drive of the little Fox. This is when I finished the seat belt and front installs, trimmed holes, added the carpet edge guard plastics at the door openings, then moved the car.

Like I said in that section above, getting the holes lined up for the seats and getting those installed took most of the day, but when I had the car ready for a test drive it was time to weigh it. We had the (43 pound) hood installed, all of the seats, the fluids, and the 6.3L engine was road worthy - and it tipped the scales at a svelte 2732 pounds. The culmination of these many months of work and we were under the 2810 pound weight that the car drove into the shop with under 2.3L power.

Cold start was perfect, idle was perfect, but throttle response was near ZERO. Again - we aren't a tuning shop. I still drove through the gears around the block, over to my buddy Paul's shop and back, about a mile. Got temps up and stable, verified all of the gauges worked (tach is reading 2x), clutch works, and no parts fell off. Success! But I had a list of last minute things to fix before we took it to the tuner on Wednesday, Dec 24th, Christmas Eve...

LAST MINUTE REPAIRS AND DELIVER TO TUNER

One of my complaints from the previous track test with the 2.3L was the wobbly steering wheel. The tilt mechanism was sloppy as hell, and Christian had to dig into the column to fix one of the bushings that was egged out. Some drilling, a bit of cursing, and it was now tight as a drum.

Another little issue was the tiny pinhole leak in the new radiator - which only leaked when it was pressurized and running. Time to pull that out and fix it.

This proved to be a bit tricky as it wasn't any of the welded bungs or brackets we added, but something in the core-to-tank interface. Not an easy fix - sounds like a job for JB Weld! Went and got some of their lowest viscosity stuff they make and it was "flowed" down into the tank interface.

This will buy us some time, but we will likely have to replace this radiator, ugh. It held pressure after it was allowed to cure, refilled with coolant, and Christian let it idle for 30 minutes before we loaded it into the trailer.

Last item on the post test drive punch list was a l-o-n-g brake pedal, so the brakes were bled to fix that. We drove it into the trailer and strapped it down, then I delivered it to the tuner on time on December 24th. Went over the various issues, including my "tuner wish list" that I explained in detail, and we'll wait for the holidays to pass before this is even looked at.

WHAT'S NEXT?

As soon as the Link ECU is dyno tuned I will pick the car up and bring it back to Vorshlag. Once back here we can finish the seat bracket base design we have started for the Fox, which we're modifying to add 2 more attachment points to reinforce the floor (a known issue). Then we can mount the Corbeau fixed back composite seats, harness bar (cringe, I know!) and harnesses.

After some more rigorous street testing, including adding some 11's on nearby roads, we'll load up the Fox and take it to MSR Cresson for some "baseline" track testing (again, but with power!)

Thanks for reading,
Terry at Vorshlag

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21st Century Fox - Vorshlag suspension development for Fox and SN95 Mustangs

21st Century Fox - Vorshlag suspension development for Fox and SN95 Mustangs

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