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Unread 08-15-2017, 11:00 AM
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Default Re: Vorshlag BMW E46 M3 CSL - V8 Downforce Monster Track Car ("Chainsaw Massacre")

continued from above


A mounting structure was built with 1" square tubing to hold the fuel cell can and dry sump tank. On top of this are the "firewall" panels that seal the passenger compartment from these hot/flammable fluids as well as the underside of the car.

The structure started out as a perimeter section of tubing and eventually lower sections were added for the fuel cell can. Then the bolt-on upper section for the can, too.

After that the bracket to hold the ARE billet oil tank mount was formed from steel sheet, with some dimple die holes to add stiffness and remove weight.


Now that the tank/cell mounting cage was bolted into the car the openings through the trunk floor needed to be sealed. There also needed to be metal coverings for the dry sump tank and fuel cell as well, to keep fluids and fire away from the cabin.

First the enclosure for the top of the fuel cell was built from more aluminum sheet.

These were cut using cardboard templates, then taped together and trimmed, tack welded and final TIG welded. This "can" mounts inside the 1" steel tubing structure.

But wait, there's more! A giant 3-piece enclosure was needed for the oil tank side. The enclosure was too tall and unwieldy to be made from 1 piece, so it's 3 pieces.

We need to make an easy to access hatch to check the oil tank levels (dipstick) and there's still a flat panel that needs to go between the two upper enclosures but for the most part it is done. They aren't exactly "pretty" to look at but they are very functional and necessary. We might add a shrubbery or something to distract the D&E judges...


To lower weight we added Lexan rear quarter windows and back windows. Then we added a fuel filler neck in one of these windows, and an enclosure around the filler neck.

We sourced the rear quarter and back windows from Five Star, a race car supplier. These were mocked up on the car above to check for fit, which was very good.


One thing I didn't get this time were the weights on the glass rear window or side windows vs the Lexan bits. I did get the weights on the HARD Motorsport and OEM E46 rear side rear windows in this July post on the E46 330 TTD car, which I copied below. The Five Star bits weigh almost exactly the same but the HM bits are much easier to mount (with their optional install kit) and come with a black outline vinyl border pre-applied to the inside.

The side windows were installed first. Like most race car parts these come with no instructions - you're expected to know what you are doing.

Ryan began by marking the outer perimeter with two lines that corresponded to part of the "black border" that would be added later as well as a centerline for drilled holes. These were marked using a compass and a Sharpie, which you can see below at left. The outer protective film was left in place as to not mark up the actual Lexan plastic.

None of the factory mounting hardware was re-used. Holes were drilled equally around the perimeter of the glass that would land in the sheet metal surround of the window. Then the holes in the windows were transferred to the body and those were center punched and drilled.

M5 nutserts were installed into the sheet metal surround for each window then countersunk stainless Tinnerman washer and countersunk stainless bolts secured the window in place. This makes for flush mount, corrosion free hardware. The factory black drip rail trim was then reinstalled.


The rear window installation followed the same techniques: marked and drilled Lexan, transferred holes and drilled sheet metal, added M5 nutserts, then Tinnerman washers and countersunk M5 bolts.

Many of you readers have seen us install and use these threaded inserts or "nutserts" on many projects. We tend to use metric splined steel nutserts in M4, M5, M6 and M8 sizes, like the one shown above left. These add a threaded hole to sheet metal that is "blind" or hard to access on the backside. There are also versions for use in plastic or fiberglass panels as well. If you can work a blind rivet gun you can work a nutsert installation tool (above right).

This is how they are installed... you drill the appropriate hole (there's a chart), install the nutsert you want with the correct "grip length" (there are longer nutserts for thicker panels), then use the tool to squeeze the insert and expand the back side behind the panel. Now you have a threaded insert that is secured in place. Sure, you could install welded inserts, but that's a lot more work. We tend to use those on thicker metal, if we cannot drill/tap it for some reason, or if we need a much longer threaded length or more strength than the nutsert can support.

Like Ryan did on the same exact brand of rear window on my E46 330, we will go back and tape off then spray paint the border on both the side and rear window on this E46 M3 at a later date. This makes the windows look a lot less "race car" and hides the visible sheet metal underneath.

We will be blowing the car apart for paint after the first track test, so we will likely add the painted borders (and some RTV sealant) to these windows then. For now they were secured in place with bolts only.


At this step we show the plumbing from fuel filler cap on the right rear window to the fuel cell, which had an ATL sourced top fill panel. This is shown with the partial aluminum enclosure around the aluminum fuel cell can in the picture below.

Because of the unusual back seat fuel cell location the filler neck was added to the right rear window. A simple fuel filler neck and cap were sourced from ATL and added as shown below.

Ryan took some aluminum tubing and welded a mandrel bend at the top to line up the filler tube to the cap in the window. A short piece of flexible tubing was added at the bottom but this is only silicone and will be changed out for a fuel safe flexible hose soon.

To make this filler neck fire safe the entire fuel fill section was then wrapped within a metal enclosure.

This is what it takes to put a fuel cell in the back seat - lots of fabrication work. An upper section to the fuel cell enclosure was built to tie into the fuel filler neck enclosure tube-within-a-tube. Ample room in the top enclosure was added to allow for plumbing AN lines from the fuel cell to the fuel pump and engine and back, all of which will run under the car.

All of this can be unbolted in sections for service, but most importantly fuel can be easily added outside of the car and end up in the fuel cell - with fire safe enclosures around everything. That wraps up the fuel cell can, filler neck, and enclosure. We still need a fuel cell bladder, which we have been trying to get quoted for many weeks.


Since this car was missing the front end, we needed a new bumper cover and bumper beam. Early in the project the customer sent us a rendering of another BMW he liked and this 1M style front bumper cover from Duraflex matched closely with the later M4 race car he found. Duraflex is a branch of Extreme Dimensions and Carbon Creations. They make a lot of bumper covers, hoods, and fenders for late model cars in fiberglass or carbon fiber. They often have unusual style changes, like this one, which was the 1M look front end but made to fit an E46 M3.

We sourced this front end early in the project and mocked it onto the car, but now it was time to mount it properly and add a bumper beam. The Duraflex material is somewhat flexible and easy to work with or modify (mostly it works like fiberglass) and it is also cost effective. It might have worked with the composite M3 front bumper beam but those are still heavy and expensive, so a tubular beam was built using the same 1.75" DOM roll bar material used in the roll cage.

Ryan built this beam using the 3 wheeled tubing roller, then built standoffs that bolt to the factory location. There are no "bumper struts", just steel tubing. From this beam he added brackets to bolt dual Setrab oil coolers up front as well.

The twin coolers line up with the outer fog light openings in the 1M styled front bumper cover. The rear OEM bumper was replaced with a similar tubular 1.75" dia beam as well. I will show that in a future update.

There was some additional structure added to hold the bumper cover along the lower grill opening. I ordered E46 M3 headlights and corner lights online, I cannot remember where. Ryan taped up the fronts and installed those before I could grab pictures, but they are just stock replacements.


We are much farther along than this post shows but I am out space so I better wrap it up here.

Next time I can cover the installation of the carbon fiber hood, the HPR built 7.7L LS engine, T56 Magnum transmission, twin disc McLoed clutch, SFI bellhousing, ARE 4 stage dry sump oiling system, rear wing installation, seat mounting version 3.0, aluminum interior panels/floors, LS7 accessory drives, custom 1-7/8" long tube header construction, and more.

Thanks for reading!
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Unread 10-10-2017, 02:42 PM
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Default Re: Vorshlag BMW E46 M3 CSL - V8 Downforce Monster Track Car ("Chainsaw Massacre")

Project Update for October 10th, 2017: Much has happened to the M3 V8 CSL project over the past two months. Last time we covered the widebody flare design and construction, fuel cell and dry sump tank mounting and enclosures, Lexan windows, and the custom front bumper beam and 1M style cover.

This time we will show the installation of the carbon fiber hood, the delivery and installation of the HPR built 7.7L engine. To that we bolted a T56 Magnum transmission, twin disc McLeod clutch, and an SFI bellhousing. Onto the new motor we attached an ARE 4 stage dry sump oiling system, a hybrid set of LS7/CTS-V front accessory drives, and then Ryan started building a custom set of 1-7/8" long tube headers. We also re-did the seat / floor mounting (version 3), built a bunch of aluminum interior panels/floors, and mounted a giant rear wing with custom uprights and end plates.

The engine bay also received a lot of attention. A custom radiator and fans were ordered, brackets were made for a "rolled forward" installation, then custom radiator hoses built. An MSD Atomic manifold and 102mm throttle body were installed - backwards - and a custom dual airbox / cowl induction intake system was then built, with plenum sections extending behind the firewall and under the dash. Continue below to see the behind-the-scenes construction of all of this and more.


The minimum weight we are allowed to run this car is fairly low in some series, and to get there we will have to eschew metal body panels for carbon fiber composites - where practical. Of course there are some exterior pieces that are very customized (flares) and it doesn't make sense to "go carbon" there just yet, but the hood, roof, and trunk panels are readily available so we went to AJ Hartman Aero for his motorsports level, lightweight, dry carbon hood to match the roof he supplied us earlier.

The first hood we received suffered some heavy shipping damage - but we purchased that one anyway, fixed it with some carbon fiber repair (shown in the 330 build thread here), and used it on my BMW 330 which I race in NASA Time Trials. With a little bodywork and paint by our friends at Heritage it will look better - hoping to paint this car over the winter break (which is only about 2 weeks long, here in Texas!)

For this M3 CSL V8 build we wanted to start with an unblemished hood, and the second one arrived (in a crate) with no issues. It looked perfect and was weighed in at an astounding 9.5 pounds! We don't have an accurate weight on an M3 hood, but the original steel hood from my E46 330 was 44.5 pounds.

I can only "one hand" this hood because it is so light, with no glossy gel coat. Many aftermarket "carbon" hoods are made by: start with a fiberglass main structure, then add a thin carbon fiber overlay, then a thick glossy coat of resin on top to make it shiny. These end up being MUCH heavier.

The low weight on this "real" dry carbon hood also comes from the fact that about two thirds of the under hood structure is omitted. AJ builds this hood with a second layer of formed carbon fiber underneath to support the OEM style hinges and some of the side structure along the length, but leaves the middle and forward sections without the ribbing. The hood is made of several layers of carbon weave. Using the OEM style hood releases is not possible - because this is a racing part.

The fenders needed adjustment to fit the hood - we bought this rolling chassis with no front sheet metal or hood installed. The OEM "J-clips" were gone so Ryan installed proper nutserts into the upper frame mounting sections. The original fenders from my blue 2001 330 were then tweaked to fit and squared to the front end, all fitted around the carbon hood (top left). One of the old hood hinges was very bent so a new one was ordered and installed (top right).

After some time re-hanging the fenders (plus slotting some fender mounting holes) and tweaking the hinges, the hood and fenders fit nearly perfectly. We'll let the body shop do the final body gaps perfect, but I'm pretty happy with how it all squared up. Its gonna be a shame to cut a bunch of holes in this hood!

Since the twin OEM hood lathes and secondary catch aren't used with this hood we will need to install some AeroCatch hood latches - similar to how this pair shown above went onto my 330 using the same hood. These have functioned great for months without issue on that car, and we have used AeroCatches on many race car builds. Ryan will reinforce the radiator support on the M3 for the two hood pins, just like he did on my 330.


This may seem excessive, to go back for a third time to modify the floor and seat mounts, but its pretty dang critical. We did this round of re-work gratis, as we just were not happy with how the floor structure turned out after lowering the seat. And frankly the seat was too low for the customer. There might be a taller driver that takes laps in this car, but the owner is the primary driver, so we build around him.

Cutting out all of the OEM seat reinforcements, the two "risers" that travel from the door sill to the tunnel, weakened the floor structure enough to allow flexing of the floor if we pushed hard enough at the top of the seat. Not good enough. The problem was we were trying to make the seat low enough so his head can NEVER come close to the upper door bars, as this car may be street driven at some Optima events on the "road rally" portion without a helmet. It is ALWAYS tricky to make a safe roll cage for a street driven car. In a dedicated race car it is assumed the driver will always have a helmet on.

So now instead of a tubular seat brace that bolts to the thin sheet metal floor, then the side brackets and/or slider bolt to that... Ryan has made this 3D structure of plate steel reinforcements that is similar in layout to the OEM stamped bits - but lower and thicker. The OMP side brackets now bolt to this reinforced structure, which is welded to the non-flat floor along the bottom seam. This new structure now takes up for the funky floor shape, is lower than the OEM reinforcements could allow, and much more rigid and strong than what we had in version 2.


We normally use the 1998-2002 Camaro LS1 front drive accessories on both our E36 and E46 LS swap kit installs, as these offer the most compact layout of power steering pump, alternator, and water pump without fouling the frame rails or inner fenders. These 4th gen drives do push the pulleys forward in the engine bay more than the Corvette C5/C6 drives, but less than the LS truck drives. For this build we knew we needed a dry sump pump and we wanted to roll the radiator, which could put the bottom of the radiator close to the engine. To make room forward we looked at the C5 and C6 accessory drives for this build, but the traditionally high mounted Corvette alternator would need to move. Plus the power steering pump would need to be deleted.


The above link from Nook and Tranny is a great resource for LS drive layouts.

You can see the factory C6 Corvette Z06's LS7 engine accessory drive setup above at left and the LS2 CTS-V drives at right. Note the very HIGH and WIDE mounted alternator, common on the C5/C6 Corvette setups. Plus the power steering pump placement for the C6 - which we don't need due to the electric EPAS steering we have added.

For this M3's accessory drive setup we used a hybrid assortment of parts: the water pump and upper tensioner/idler from a 2010-13 Corvette C6 LS7 and the low mounted alternator and idler pulleys from a CTS-V LS2. Ryan machined a custom spacer, used a threaded hole on the CTS-V alternator bracket, and added a second "smooth" idler pulley near the alternator - the lower one shown in the picture, above right. The Pontiac G8 alternator bracket we used on some other Ls swaps sits in a similar spot but uses different brackets. This second idler helps give enough "belt wrap" around the main balancer pulley for the unusual "power steering delete" belt routing.

We chose the later LS7 water pump, which moves the water neck closer to the driver's side - making a shorter hose run to the radiator. Since we had never done this custom accessory drive layout before, once the final engine was here (with the balancer installed by HPR) a bit of measuring and a couple of belts were tested before the final serpentine belt length was nailed down.

While the HPR shortblock was awaiting the CNC cylinder heads, we borrowed the ARE 4 stage dry sump pump temporarily - to make sure we had no interference with the accessory drive bits we planned to use. The dry sump pump fits in the spot where the A/C compressor mounts - low and to the passenger side of the engine.

So this hybrid accessory drive setup gives us the best of both worlds: a low mounted alternator (CTS-V) along with a short drive setup front to back (Corvette). This added room up front with this drive setup will come in handy when we mount the radiator (below). This also opened up the top of the engine bay, near where we will duct the hood later.


For an engine this big something larger than our production E46 LS Swap 1-3/4" primary long tube headers were part of the plan. We couldn't wait for the finished HPR 7.7L long block to arrive to begin the custom 1-7/8" primary header fabrication, so a mock-up engine and new accessory drive were installed for the early fab stages.

We were using bends, flanges, and collectors from a new supplier, and there were some... "issues outside of our control" that slowed delivery of the additional parts we needed to finish these for a few frustrating months.

There was also an extremely long delay waiting for a new set of ICE Engine Works modeling bends for this 1-7/8" primary size. After months of waiting we finally punted and used our 1-3/4" (orange) bends to simulate the layout of the tube for the larger tubing size. It slowed things by a bit but Ryan got through the driver's side header.

During one of the extended waits for more bends the custom steering column was completed with this firewall mounted steering shaft bearing. The somewhat large factory hole for the OEM column was closed up, then a new hole was drilled to fit the bolt pattern of the firewall bushing.

While he was working on the firewall, Ryan made a template (above left) then an aluminum panel with a 3D shape (above right) to cover holes in the firewall for the brake booster/master cylinder and a wiring harness. This panel was then covered in DEI reflective gold foil. With that area sorted out, the final section of the header on the driver's side could be built - if we only had supplies.

A couple of months later we finally had enough matching bends - and the driver's side header is complete. This past week Ryan was on the passenger side header, which will be wrapped up soon.

continued below

Last edited by Fair!; 10-10-2017 at 04:07 PM.
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Default Re: Vorshlag BMW E46 M3 CSL - V8 Downforce Monster Track Car ("Chainsaw Massacre")

continued from above


We ordered a 442" stroker engine for this project last year, before engine builder Erik Koeing moved to a new shop in McKinney, Texas. While instructing for at the School of Automotive Machinists (SAM Tech) he started his own engine shop 2 decades ago. Koeing and I have been friends for 30 years and another business owner friend of mine and I partnered with him to bring his shop to the Dallas area, which we relaunched as HorsePower-Research (HPR). He has been working with LS engines since they were introduced, and the standard deck aluminum block 468" is one of his popular creations. After he was setup in the new shop we changed the 442" build to a 468", changed the cylinder head choice to an LS7 style, and this pump gas fueled, naturally aspirated 7.7L beast was the result.

This engine started with a dry sleeved, aluminum OEM block with a 4.250" stroke and honed to a 4.185" bore. The forged crank uses HPR's propriety forged rods and pistons, coupled with some block clearancing, to make it all fit. Koenig has built dozens of these 468s for street, drag race and road racing applications - the biggest displacement anyone has safely built inside an OEM LS block.

The blueprinted shortblock was assembled with CNC ported, LS7 style cylinder heads made by Texas Speed. A high lift hydraulic roller camshaft was built to Koenig's specs for this pump gas, road course setup. A similar 468" was recently built for an Optima competitor and made 604 whp - with smaller heads, smaller cam, and smaller headers (described here). We're hoping to see 650 whp from this on 93 octane, with the intake manifold we have started with.

We were excited when the cylinder heads arrived and I could pick up the completed long block. I brought it to Vorshlag for final drivetrain assembly and installation into the M3.


To deal with 700 ft-lbs of torque we went went with the strongest commercially available 6 speed manual - the Tremec T56 Magnum. This Tremec is rated right at 700 ft-lbs of torque, which we will be testing with this engine.

This build has higher safety levels than most so an SFI rated scattershield was chosen instead of a cast aluminum bell housing. This unit from QuickTime bolts to the T56 Magnum and fits the LS engine. Well... "fits" is a loose term.

For the clutch we went with a custom version of the Mag Force twin disc setup from McLeod, highly recommended by our transmission supplier. This has a unique Kevlar friction surface that should work well with the standing starts needed for Optima Speed/Stop and Autocross events and still handle the power this 7.7L can dish out on the road course.

Everything was assembled with care, checking torques and sequencing. Once everything was lined up the bell housing was aligned to the centerline of the crank by checking run out with a dial caliper. The twin disc clutch was aligned with a steel alignment tool and the transmission was installed... but it just would not line up.

The clutch, flywheel and bell housing were re-aligned and re-checked more than once. Turns out that aftermarket welded scatter shields sometimes don't exactly line up as perfectly as a cast piece that is CNC machined. Using some offset dowels in the block and this scatter shield alignment tool above the QuickTime unit was finally aligned.

The McLoed clutch slave/TOB was installed for the final time and the transmission went into the bell housing. The engine/trans was finally ready to go into the engine bay of this M3.

With the front nose and radiator support removed its easy to stick the engine and transmission assembly into the car. We used our production E46 LS swap kit motor mounts and transmission crossmember to line it up in the engine bay.

The dry sump pump was bolted on once the engine was in the car, to avoid smashing the shiny bits or fittings. The front drive accessories were already installed with the serpentine belt, then the cogged belt went onto the dry sump drive.


Spec'ing the radiator for this project took a little bit of work. This 7.7L motor would need the biggest radiator we could fit in front of the motor. We also wanted to duct the hood and "roll" the radiator forward at the top, so that meant we wouldn't be using an off-the-shelf aluminum E46 radiator.

I asked Ryan to clear away anything in the way between the frame rails then measure for the widest core we could squeeze in there (27"). The center portion of the lower stamped piece of the radiator support was completely cut out. He then built a cardboard mock-up to verify the max height core possible. Then we had to spec the hose outlets for an LS engine accessory layout, with the suction on the passenger side and water pump outlet on the driver's side. The goal was to shove as much of the radiator forward under the radiator support as possible without running into the front nose or crash beam. Unfortunately the headlights became a limiting factor for forward roll of the radiator, so the bottom of the core was pulled back closer to the balancer, to gain more angle and radiator height room.

The mock-ups and other specs led us to a BeCool 60229 radiator, which was custom ordered back in May. It took a while to be built and shipped here but when it arrived Ryan made brackets to mount it in the layout we wanted.

After the motor was installed with the balancer in place the BeCool unit was mocked-up in the final rolled forward position. Templates for brackets were cut and transferred to aluminum plate, which were cut, drilled and welded to the side tanks of the radiator.

The brackets were drilled for mounting holes that allowed them to bolt to the frame rail. Nutserts were drilled and installed into the frame rails for these mounting bolts, shown below. These initial mounts are bolted directly to the frame but about 1" of room was left to add some isolators. We will do this when we build the ducting, as well as possibly add a secondary set of mounts at the top and/or bottom.

More calculations were done and the slimmest, highest flowing pair of fans that covered the most area of the core were ordered.

These Mishimoto Slim 12" electric fans (MMFAN-12) each flow 1150 cfm. A bracket was built along the top and bottom to mount them close to the radiator core. There are more powerful fans in 12" but they were all thicker and could run into parts of the engine.

Some custom radiator hoses were built from HPS silicone hose bends and some mandrel bent and straight aluminum tubing. The front of the radiator core will be ducted to the gill openings at the front and to the hood opening behind it - we will show this later in the build.

continued below
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Default Re: Vorshlag BMW E46 M3 CSL - V8 Downforce Monster Track Car ("Chainsaw Massacre")

continued from above


After talking to Koenig at HPR at length about intake manifolds, he kept stressing how important it was to use the right design for larger displacement (7L+) engines. To keep the engine from peaking too early, and losing all of the top end power, a shorter intake runner length (6.5-7" long) with enough cross section and throttle body size would help. There are many manifolds that have MUCH shorter runners (which kills mid range completely and rarely helps on top in an NA motor) and all too many with OEM style, LONG runners (which shuts off the top end). Not many in the middle...

One of the few that have runner lengths and TB sizes in the range we wanted was the Holley Hi-Ram, which comes in cathedral, LS3 and LS7 style ports. With an optional 105mm throttle body opening and a 6.5" runner length (which is almost perfectly straight) the Hi-Ram could be worth another 30-50 whp up top. After I found the CAD print (top left) for this I asked Ryan to make a quick cardboard mock-up to check hood height. That was ridiculously too tall, and even flipped 180 to make it a "cowl breather" it was still many inches above the hood line (see above right). Like "making it hard to see" tall. We talked about making a custom intake but it was really time to "get going" so we picked the best OEM style intake on the market for the moment: the MSD Atomic.

Of the OEM style crossover intakes the MSD Atomic LS7 intake has the "least long" runners at 8.5". The 103mm throttle body size is a bit unusual, as the common "big" sizes are 102 and 105mm. Then a lot of those options are cable operated - old school. To work seamlessly with a Motorsports traction control system we went with a Nick Williams 102mm DBW (Drive By Wire) throttle body.

This manifold bolted onto the HPR motor without any drama, and with the TB opening pointed forward it fit under the hood easily. But we're not going to keep this build easy... we wanted to flip the intake manifold 180 to keep the front clear for hood ducting (which we will show in a future installment) and to take in high pressure air at the base of the windshield (cowl). This "little change" unleashed a lot of custom fabrication work....

First of all, the OEM cast aluminum intake valley cover has an oil pressure riser cast into the back of the motor. You can see the red colored tip of this riser in the image above left. Most LS style intakes have a recessed edge to clear this at the back of the manifold, which can be seen in the image above right.

So to be able to flip this intake around we needed a flat valley cover with this oil pressure sensor riser deleted. This flat billet cover from ICT fit the bill and was an easy fix. This was installed and let us run the MSD Atomic flipped 180. But as you can see above, there was no room at the firewall for the throttle body. I was hoping the TB might line up with the massive opening left by the cabin air filter structure, but this intake is too low to line up with that. Time to cut...


To make this flipped intake fit we needed to cut the firewall up a little. Well.... OK, a lot.

This was the first stage of making a cowl induction intake system. You see with a mostly gutted dash and aftermarket HVAC box mounted elsewhere, and relocated master cylinder and no brake booster, all of a sudden we had a lot more real estate under the dash and at the firewall. So Jason, Ryan and I brain stormed an airbox mounted at the base of the windshield with a flat air filter element. Or two.

To maximize airbox volume we wanted to use a flat element air filter. Due to some space constraints in area, as well as off-the-shelf filter elements and their associated airflow limitations, we needed TWO air filter boxes. So we ordered those up while Ryan started building a plenum at the throttle body.

This box above will attach to the 102mm throttle body and create a certain amount of plenum volume for the engine to draw from. Air will enter through each of the 3" oval openings from the two air boxes. The constraints of the hood and engine placement limited the intakes to these 3" oval sizes.

The 4" opening to the throttle body has a formed bell mouth and the box itself sits up under the dash. Ryan will make another fire proof enclosure to completely surround this and seal the engine compartment away from the passenger cabin/dash area (see below/left)

Twin air filter boxes were built, one for each side of the engine bay. They are somewhat mirror images but they do have some differences side to side, which are underneath.

These air filter boxes mount to the chassis and then 3" tube and 3" silicone hose couplers route the "cold air" to the throttle body plenum box. Two K&N filters fit snugly into the tops of these air boxes and we will add some additional structure and seals that touch the bottom of the hood soon. These will mate up with two big holes we will cut in the hood to feed these filters.

A couple of dozen hours went into the firewall clearancing, layout, plenum box fab and two air box fab work, but it should be more than able to supply this air to engine. This is being fed by a high pressure zone at the base of the windshield, which will help "at speed". And it all will help the Optima Design & Engineering scoring, too. Again, this is really being done to open up the front of the engine bay for hood ducting, to improve downforce on the splitter (soon) and improve cooling on the main radiator.


Up to this point we haven't shown much of the interior or our plans to make it safe yet pleasing to the eye. Gotta pass muster for D&E - they really punish gutted race cars in Optima, unless some real attempts at "an alternative interior" are made. Initially we just had roll up windows and custom door panels, but the rest was pretty Spartan. All business, no frills, and somewhat ugly. Time to spruce it up in there...

This interior was largely gutted when we found it, along with the air bags. The stock HVAC is also too heavy for a build like this, but we did add a compact heater core and blower motor unit that we've used on a number of race cars (just like on the tube frame 69 Camaro build). This 7 pound unit from Summit Racing is cost effective, compact, and much lighter than the OEM parts. This box was mounted under the dash on the passenger side and the outlets will be plumbed to the defroster vents soon. No air conditioning is going to be added - too heavy, and there is no place to drive an AC compressor with a 4 stage dry sump pump in the way.

Another Tilton triple reservoir was purchased (also like on the 69 Camaro), which will feed the twin brake and single clutch master cylinder from the OBP floor mounted pedal box. This Tilton unit was mocked up and then mounted on the passenger side. Why have this in the passenger compartment? Three reasons. 1) Being visible to the driver makes it easy to see if fluid LEVELS drop during a session (indicates pad wear or a leak). 2) It makes it easy to fill the fluid levels, not buried down by the floor mounted pedals. 3) It keeps the bulk of the fluid away from heat in the engine bay.

A few weeks later Ryan went back and made -4 AN braided lines for the reservoir and ran them to each master cylinder.

The spot your heel rests on at OBP pedal box was tied into a flat, false floor made of aluminum. A formed sheet aluminum dead pedal was also built and tied into the same section. These false floors are commonplace in race cars, and with the unusual non-flat floors of the BMW E46 they are pretty much a requirement if you remove the carpet and massive foam backing.

These were formed from 6061 sheet then dimple die holes were added on the press. We will add grip tape to the surfaces later, to keep your feet from sliding around if they get wet. The passenger side false floor was started but still needs some dimple die work.

We couldn't leave the stock steering wheel in place so we ordered a Sparco wheel and Lifeline quick disconnect hub. This wheel fit the driver's position and has the right covering, and the Lifeline is the best quick disconnect on the market.

Window nets might seem a bit extreme for a car with roll up windows, and it is unusual. But for a "street car" this M3 has an unusually high speed threshold, so the safety gear isn't being skimped anywhere. This mesh window net has great visibility but keeps "your arms and hands inside the ride at all times". We will add a center net later as well.

A lot of aluminum panels were built, which help fill holes in the dash where the radio, HVAC controls, and stock gauge cluster went. An AiM digital dash, possibly a rear view camera/LCD screen, and the fire pulls and main battery kill will go back into these places. A new set of "Titanium" OEM trim panels was ordered from BMW and installed to fill the gaps between the 2-pieces in the upper and lower dash sections. We will get a little crazier with interior panels and finishes before the car ever does an Optima event, but its already a lot better than the plain "gutted race car" look.

continued below
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Default Re: Vorshlag BMW E46 M3 CSL - V8 Downforce Monster Track Car ("Chainsaw Massacre")

continued from above


"Big Downforce" is part of the "Bigger is Better" mentality we are applying to many aspects of this build. Of course a giant rear wing was ordered from AJ Hartman Aero - a full 72" wide and with his longest 14" cord.

We have installed plenty of rear wings but on a car that could see speeds in excess of 180 mph, it needed to be a bit overbuilt.

After deciding where the uprights would be (and thus the under-mount saddles) we ordered the wing. When it was delivered we played with mounting locations, getting the element where it could "do the most work" - way up high and far back - then Ryan made cardboard mock-ups, which progressed into plate aluminum versions. We had thought about a bent upright, but that was quickly abandoned in mock-up.

We settled on this flat design that would be gripped with a steel U-shaped lower bracket, that could then be bolted to the trunk.

Once these were cut, brackets made, and they were test fit the lower steel brackets were bolted to the trunk lid. The OEM steel trunk lid is very strong but we also extended the lower portion down to touch an adjustable perch onto the tubular rear bumper beam. We will made a "saddle" that looks prettier before paint, but this puts much of the vertical load into this beam and less on the trunk structure.

The trunk can swing open fully and the wing element clears the roof easily. This is due to the rear biased, high mounted placement of the wing element.

The "windows" above were cut out by hand - using a hole saw and jig saw. There are much faster ways to do this using robots... a CNC water jet or plasma table makes this much faster but we didn't have the time to transfer all of this into CAD then run use someone's table. Yes, I need to buy the shop a CNC plasma table...

The lightened uprights were completed and then endplate designs were tested and tweaked...

Some details on the image above (red line) have been completed but its the best picture I have of the finish wing currently.

GTL class - any spoiler or wing configuration with a maximum of 6 tall from its highest mounting point or a maximum height of 4 above the lowest point of the rear window, whichever is less. The maximum width of the spoiler/wing must be no wider than the original panels of the car and must not extend more than 6 inches past the furthest point of the rear of the car. No wing may exceed 8 inches in chord length (front to back) at any point.
We know that the 2017 aero rules for Optima are pretty limited and we will create a separate aero package for that series. We will use a carbon fiber trunk to mount that Optima aero package, which would make for a simple "trunk swap" to be legal for that series. The big wing would be used in NASA and other events.

A massive splitter, the soon-to-be ducted hood, and some other bits will make up the front aero. We just made this front splitter for my 330, but the one for the M3 will be bigger in every way.


Wow, that was a lot of ground to cover, and I didn't get to everything that's completed. Next time I will show the twin fire systems, chassis wiring that has begun, the fuel system components that have been arriving, and the Motec M1 + wiring harness which is being built by our friends at G-Speed.

The rear differential is now assembled with a Wavetrac LSD and Ford Racing gears, the exhaust headers should be wrapped up soon, and then a driveshaft and exhaust can be built after that is in place. The custom coolant reservoir was just completed, heater hose plumbing has begun, and Ryan is spec'ing out the oil hoses next.

This is what the M3 looks like today. Tune in next time to see more progress!

Thanks for reading,
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