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Unread 08-22-2012, 03:24 PM
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Default Vorshlag Miata LS1 Alpha Project

New Project Introduction : Many of you reading this already know about Vorshlag's history with installing American V8s into European sports coupes and roadsters, but that wasn't the first V8 swap that I contemplated. Back in 1998 I purchased a 1992 "NA" 1st generation Miata. I bought it wrecked, repaired all the bodywork, and had it painted with the intention of building a 302 Ford V8 powered "monster" Miata. That was right around the time when the LS1 engine was just being introduced into the new 1997 C5 Corvette and 1998 Camaro/Firebird.

Note: To help me keep track of which forums this build thread is cross-posted, I have made this list...

A couple of BMW E36 chassis with our LS1/T56 swap kit, shown above. These can weigh 2550 lbs (without interior) to 3100 pounds (fully optioned)

At the time I owned this '92 MX5 we were moving from Houston to Dallas, so the Miata V8 swap was mostly ignored, then became a seldom used daily driver for a couple of years. During that time I also owned and raced an LT1 V8 powered '94 Corvette and a supercharged LT1 '94 Trans Am, but I noticed quickly that the all-new "gen III" small block Chevy LS1 engines were a cut above the "gen II" LT1 motors. Deep skirted all-aluminum blocks with 6-bolt mains, incredible cylinder heads, and lots of new technology - but the same narrow/compact architecture of a "cam in block", pushrod V8. I was quick to get my hands on LS1 parts, weighing blocks (109 lbs) and heads (21 lbs) and learning quickly that these things are very light. And they were making more power, dollar for dollar/mod for mod, than anything else out there.

Comparison of Miata drivetrain next to LS1/T56

We completed the move from Houston to Dallas and the plans for little Miata V8 project switched from Ford 302 to Chevy LS1 V8 power. I started to accumulate LS1 bits, but the Miata (one of a half dozen cars I owned at the time) was parked outside and got hammered badly in a hail storm. This was a big one - it blew out skylights, ruined our gutters and roof, and utterly destroyed two of my cars. I was "SOL" and sold the Miata for a bit of a loss. My V8 swap fascination changed focus to a BMW E36 with LS1 power, and in 2002 that project began with the same block I had rounded up for the Miata. Since then we've sold dozens of E36 BMW LS1 swap kits, made an E30 BMW LS1 (our $2011 GRM Challenge winner), Z3 LS1s, and are deep into a new E46 chassis LS1 swap. We have several E36 LS1 turn key swaps underway right now, too.

Even Mazda knew the 1.8L wasn't enough. Here's a factory built NB test mule with a Duratec V6. Why was this never built?

But this whole time that Miata LS1 swap was bugging me. It was an unfinished project that I had let slip by. A thorn in my side every time I saw people talking about the various LS1 Miata kits out there. Sure, the V8Roadsters LS1 swap kit sold by Flyin Miata looks very nice, and the new Boss Frog kit has a different take on it. They have fine products and I am not saying otherwise. But... I could see little improvements we could make, significantly different parts choices I was familiar with from my years of building/owning/racing Corvettes, F-Bodies, and Mustangs, and maybe some improvements that could come from our decade of working with LS1 V8 powered BMWs. The question I put to myself earlier this year was: Should we jump into this market with our own LS1 swap kit for a Miata??

Yes, we are making an LS1 swap kit for Miata's

As you might have guessed, we are going forward with this swap. Why would I start this thread if we weren't, right? Our BMW LS1 swap business has been growing lately and we have been taking on turn-key swaps in addition to the already robust E36 LS1 swap component manufacture and sales. We all love this Miata chassis, it is so abundant that it has become very affordable, but they are just... lacking in horsepower. An LS1 fixes all of that.

Our first Miata V8 candidate, or "Alpha" Miata, is a 1999 "NB" 2nd Generation Miata that weighed 2342 lbs with 1/2 tank of fuel

For now, we are going to concentrate on the 1999-2005 NB chassis and skip the 1990-1997 NA cars, just because they are getting a bit long in the tooth. The prices aren't that far apart for clean swap candidates, looking between the NB and NA Miatas. The 3rd gen NC MX5 chassis is significantly different from the NA & NB cars, and used car prices are still pretty high, so we are not going to delve into an NC LS1 swap right now.

Left: Miata "BP" 1.8L engine weighs 348 lbs. Right: Miata 5-spd manual transmission weighs 85 lbs

Some of the weights involved are shown above and below, from weights we have taken. Looks like the 1.8L Miata motor and 5-spd trans together weigh 433 lbs, with accessories. Not bad for an iron block 4 cylinder. By comparison the BMW E36 chassis' 4 cylinder M42 DOHC 4 and Getrag 5-spd are 429 lbs, which is almost identical. The big 5.7L LS1 V8 weighs 457 lbs soaking wet, with all accessories (and has more than triple the displacement and triple the power of the Miata 1.8L). The 6 speed Tremec T56 (from the 1998-2001 Camaro) itself is a portly 125 lbs, but it's a big strong transmission with two overdrives. That should give us a 582 lb drivetrain, if we stick with the T56, or an extra 149 lbs over stock. The combined "609 lb" weight shown below was indeed for an LS1 and T56 drivetrain with accessories, but also included a stock Camaro engine harness, MAF sensor, and engine computer.

Left: The M42 1.8L DOHC 4-cylinder and Getrag 5-spd is 427 lbs. Right: A fully dressed 5.7L LS1 + T56 at 609 lbs (click to enlarge)

Why do we love the LS1 V8 so much? Well, there are several reasons. It is a compact and light engine, as I mentioned before. It has been used in literally millions of cars and trucks worldwide since 1997, in so many variants - iron and aluminum blocks, and factory displacements that include 4.8L, 5.3L, 5.7L, 6.0L, 6.2L, 7.0L - that are all dimensionally identical. With aftermarket support that dwarfs almost every motor in existence, there are essentially no limits on power goals, which aftermarket engines that can make 8.5L and boosted engines pumping out 2500 hp. A common build is to use a nearly stock aluminum 5.7-6.2L LS1 series engine and make 350-450 whp, with a mild camshaft, good street manners, and great power under the curve. Even "only" 350 whp in a 2500 pound package can be a total blast at an autocross or track event. A little more displacement and/or compression+camshaft can get you to 500 whp, which is a LOT of fun.

Our first steps included finding a willing Alpha customer, which we found in Jason Toth. He was eager to become our first test customer and on his own he rounded up this highly optioned, 1999, silver 5-spd Miata that needed a little help and wasn't anything super rare, so it will make a great swap candidate. Once the car was here, we took a ton of measurements and fixed a few little things on the chassis that were going to stay. Then the OEM drivetrain was pulled out so we could take a closer look.

The car was coated in oil underneath from a leaky front seal, so we gave it the full pressure wash treatment under the hood and on the bottom. Once the car was in the air I noticed the relatively large transmission tunnel, so I was pretty confident we could make the Tremec T56 or something like it fit without too much trouble. We might go another direction with the transmission, with two other possible gear box candidates, but I will share more on that soon.

First test fit of our mock-up LS1 and T56 transmission

Once the stock drivetrain was out, we shoved our "mock-up" LS1 engine and T56 into the little car. The initial fit wasn't half bad, but there are two corners in the firewall that really limit rearward movement of the V8 engine's cylinder heads. Our guys cut some small notches back there (which will be covered in steel when the final engine placement is locked down) and re-installed the LS1/T56 drivetrain farther back, and now it looked much better.

Well we're committed now! You can see the corners we trimmed to make the LS1 fit farther back, which lines up the shifter nicely, too.

After seeing this second test fit's engine placement, we were happier and now know which oil pan should work perfectly. We've also got a good idea on how we want to build the new front crossmember, which will be a custom tubular design utilizing mostly stock suspension geometry. Definitely some weight to be lost there. The rear differential was also mocked up with an aluminum Ford 8.8" 31-spline differential carrier from a 2003-04 Cobra. This will need another custom subframe to mount this diff carrier, plus some other parts we will discuss later.

Vorshlag LS1 Swap Goals

I don't want our kit to be just another "me too!" option for the Miata V8 swap world. Although some of the steps and parts will be similar to the other kits out there, we plan on doing several things very differently. In order to make the drivetrain work how we want, some of the major changes will have secondary effects, including some upgrades to other areas of the car. These "forced" upgrades will work in harmony with the rest of the swap to keep up with the speed potential of the ~400 whp LSx powerplant that most customers want. Again, these upgraded components will be shown as it they are developed.

The factory NB Miata Power Plant Frame is shown in the pictures above (click to enlarge)

One major change I proposed was trying to keep the factory Power Plant Frame (see above), which is the big aluminum C-channel shaped structural member that attaches between the factory Miata transmission and rear differential carrier - giving the chassis much needed rigidity. All of the other V8 swap kits do away with the factory PPF and replace it with big slabs of steel in the form of subframe connectors, and another big hunk of steel that bolts between those to become the transmission crossmember. My initial idea might not work, but we're going to try it - as keeping a PPF could both save weight and keep the chassis stiffness using the same style components the Mazda engineers started with.

In the end, I want to see a 2500-2550 pound finished weight on this fully optioned, full interior, street car build. That means only +150-200 lbs total weight added over stock. And yes, if you are keeping up with my math that's barely enough added weight to cover the increase in drivetrain weight over stock (+149 lbs), so we have some weight loss to concentrate on. That's what makes this swap worth doing - light weight, lots of power, small car. I am hoping that the custom PPF, our tubular subframes, and some of the other potential differences on our proposed LS1 swap kit will help save some weight over the Boss Frog (+300 lbs over stock ) and V8Roadsters (+200 lbs over stock) swaps. Who knows - we might miss that goal, but we are going to try. Again, we're beefing up some other systems (that might add some weight on their own) to match the performance of the LS1 engine that most other kits completely ignore. Only way to know is to try our ideas and scale the parts continuously throughout the build. Every stock piece that comes off will be weighed and so will every part that goes back on.

Sharing The Build Online

As usual we will post updates on this project and share them with the online community during the Alpha build. Perhaps it is not smart to show our project this early in developmental stages, but that's how we've always done it. In the end, we always get good ideas from forum readers, as there is always someone out there that has run into something we might not be familiar with. We do have some very experienced Miata guys in house, as well as good fabricators and a decade of experience in the LS1 swap world. It would be foolish to think that "we know more than everyone", and we can always learn something from someone. If you see something that could be done better - feel free to speak up!

Since some of my ideas might crash and burn as we progress, I'm not going to give away all of our thoughts up front. Some will become obvious as the build progresses, and whatever we end up with will have tons of pictures and data shared along the way. We also reserve the right to change directions on a particular goal, part choice, or theory as we progress - because on this first build I am sure we will learn as we go. Whatever we do, we will try to post regular updates as the build progresses.

When Will It Be Done?

This is a question I hate answering, because the answer is vague: "It will be done when it's done". There are so many things going on at the Vorshlag shop, which is a company primarily focused around developing, building and supporting suspension products. The LS1 swaps are too much fun so we also spend a good chunk of our time building, developing and supporting these swaps now, too. We are already well underway on a new BMW E46 LS1 swap kit & Alpha build, have some new things coming for our BMW E36 LS1 swaps (as well as three turn key builds), and more.

Just know that this Alpha LS1 Miata build is not going to happen overnight. This is not a "one-off" build and it has the extra burden of a future production swap kit riding on it as well. We will take what we learn in this build to create production fixtures so we can manufacture parts in batches made to tight tolerances. Then anyone with some basic tools can use our kit parts on their NB Miata, install them in their own garage, and have them fit without major hassles. The users and production variables dictate how we can implement some of our V8 swap solutions, as always.

So if you absolutely gotta have a Miata V8 right now, then we aren't your source. Check the links I have included above for the competing LS1 swap kits, which are in production today and I'm sure they'd love to have your business. I'm going to stop here, as I have four other build threads to update or start (Pikes Peak STi, BMW E46 LS1 Alpha LS1, McCall's BMW Z3M LS1, and the Subaru BRZ build thread).


Last edited by Fair!; 12-18-2014 at 03:13 PM.
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