LSA Supercharged 86 Porsche 944

I'm only a few weeks away from completion (hopefully) so I figured I would go ahead and begin documenting my build process and finally contribute to this phenomenal forum. I will start with a quick write-up of what I am starting with, what parts I have acquired for the build, and my desired end state. This first post will focus on the beginnings.

So, there I was looking for a daily driver that doubled as a means of transportation from point A to B and as a kick ass, go-fast, joyriding machine. I figured if I was gonna drive something everyday it was going to be something I would LOVE to drive everyday. This obviously meant I would be building a supercharged LS as the power plant but what on earth would I put in? I initially set out to build a LSA boosted minivan (two kids) but could not find a minivan that would fit an LS for under $15K. I really didn't want to spend that much for a donor body so I changed gears and found this amazing forum (and TPC), which led me to the Porsche 944.

I first picked up a used 5.3L LS long block for $400. I wanted a 5.7L LS1 but they were going for $1500 for just the block and I wanted to keep the overall cost of the build under $8500. Plus, you can't beat a complete LS for only $400. I picked up a used LSA supercharger off ebay for $900 and some used 241 cast heads locally for $200. I dropped the 5.3L and heads off at the machine shop for a good refreshing and CNC work. The rest of the parts I pretty much ordered new over the period of a few months while I kept a sharp eye out for a nice 944.

After browsing the classified ads for a good while, I finally found a nice 86 Porsche 944 N/A for $3500. It had minor damage on one of the fenders but the interior was excellent and ran and drove great. The guy had several 944s (he is an old retired Brit who spends his free time fixing up European cars) so I paid full price and he threw in a new fender and offered me free pickings of any part I may need down the road. So, with my power plant and donor body both in my possession, I focused my attention on developing my plan of how to go about tackling this task. To be continued...

After doing copious amounts of research into the matter (there are various write-ups and blogs), I decided to remove the 944 engine from the top using my engine hoist because it seemed like it would be extremely easy...and it was. I simply removed the hood to allow complete maneuverability of the hoist. After that, I essentially just followed the steps on the following blog: [You must be registered and logged in to see this link.]
I decided to leave the complete intake manifold on because I didn't see how it would interfere with anything during the removal and it didn't. I had a wooden platform from a crate sitting next to the car that I used to drop the removed 944 engine onto in preparation for packaging. All in all, it was a fairly simple process and took less than two hours.

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This sounds like quite a build! How is the LSA blower for hood clearance? What are you planning for a transaxle?

superman22x wrote:This sounds like quite a build!  How is the LSA blower for hood clearance?  What are you planning for a transaxle?

I was expecting to have to cut out some of the hood for the blower to clear but it turned out to be much more of an issue than originally thought. I didn't use the cross member spacers since I knew the lsa wouln't clear the hood anyway and I made my hydroboost bracket mount approx. 1/2 higher to clear the valve covers. All-in-all, the lsa peeks out of the hood a good 5-6 inches as you can see in the pic (spoiler alert* sneak preview). I'm in the process of fabricating a shaker style cowl to "church it up" a little. I want the black lid to be exposed to ambient outside temps instead of engine temps to help keep air temp down. I'll add more detail in my posts as I get closer to the more unique steps of the build.

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I'm going to keep the N/A transaxle for the time being until I can get a Turbo trans. Then I plan on rebuilding the Turbo trans, adding the taller 5th gear from the N/A, and keeping that as my setup. Unless I break it then I may be searching for other options, but until then...

I like

PART 2: Hydroboost and DBW

So, while I had the block and the heads at the machine shop, I focused my attention to rounding up all the parts I projected I would need so that I can take about a month off work and cram the boosted V8 into the little 944. I scoured the forums here for weeks taking note of all the parts that worked and what didn't, it really saved me a TON of time and effort (THANK YOU ALL SO MUCH!!!!). Since I had an empty engine bay, my next step was to pull off the old vacuum brake booster and begin the prep work for a Ford Cobra Hydroboost setup.

I didn't really want to use spacers to drop my cross member down (even though I obviously needed as much room as I could get) because I have read a few places that it can change the steering and possibly cause bump steer. So, I designed and fabricated a mounting plate that allowed the hydroboost system to be moved up about 1/2 inch, any more than that then the brake/clutch reservoir would have interfered with the hood. This turned out to be a lifesaver as it gave me just enough clearance between the driver side valve cover and the hydroboost. I will drill a mounting hole in the brake pedal that is slightly higher the factory hole in order to keep angle correct. Probly save that task for last because it was a PITA to crawl under the driver side dash to get everything together.

While installing the hydroboost system, I also fabricated a drive by wire (DBW) pedal setup since the LSA only uses a DBW throttle body. I figured it would be far easier to switch the 944 to a DBW setup than try to fab a cable driven throttle body to the LSA. I picked up a used 2003 Tahoe DBW pedal assembly complete with the control module for about $90 off ebay. The Tahoe pedal was much larger than other pedal types and the angle from the sensor to the pedal was fairly straight. I disconnected the factory pedal from the lever but left it attached to the floor board. I then removed all the cables and levers associated with the old 944 throttle system, including the cruise control box under the hood on the passenger side as I had plans for something else to go there. I did leave a small bracket that connects the 944 throttle linkage to the firewall and used it to mount the DBW mechanism. Once I got the DBW mechanism where I wanted it, I cut a good portion of the pedal arm off to allow room for connecting the 944 pedal to it. I then cut off the bottom portion of the old 944 pedal lever (the part that attaches to the pedal itself) and reattached it to the pedal. Next, I drilled two holes in both lever portions and connected the two together. There ya have it, DBW complete. I will be sure and add pics of my hydroboost and DBW after I get some taken. I didn't take pics during the early stages of the build...sorry. Until then, here are some more shots of the boosted beast.

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very nice. Whats the HP of that unit?

kevin924kevin wrote:very nice. Whats the HP of that unit?

From the research I have done, the average output is about 475-500 hp/tq at the wheels. I'd be happy with that but am a little worried about the trans holding up to that abuse. I got a pretty beefy clutch and pressure plate so the weak point in the drive train is likely the trans input shaft at this point. When I acquire a turbo trans, I plan to spend a little money on it and get hardened internals where I can. I read somewhere that even the N/A trans is rated at 400 lb/ft so it may handle it for a good while.

the major weakness in our transaxles is the final drive. the n/a trans has a weaker center casting and is known to break around the rear pinion bearing, this is caused by excess pinion load, the end result is catastrophic failure. the turbo trans reinforced this area, but heavy pinion load can still break it. the reinforcement plate essentially fixes this issue, however it just moves the failure point to the next thing, the ring and pinion. the gearset in these transaxles is tiny, around a 7" diameter ring gear, and the pinion is equally as small. the teeth are small, and just cant take high load.

the turbo transaxle is stronger, the taller final drive makes the pinion gear larger making it stronger in itself. other changes were made to make some of the gears a little stronger. the turbo s transaxle (AOR) is a regular turbo transaxle and had shot peened 1st and 2nd gears added, as well as the input shaft was shot peened, this is for added strength. the lsd also was tweaked for better performance. this is the strongest 944 transaxle out there, however at 500hp/tq id still consider it to be like glass. some people have run them with this sort of horsepower with n/a v8 swaps, however you need to be careful with them. if you try to launch it you will be going home on a tow truck. even with an aggressive clutch if you make a wrong move it could spell disaster.

unfortunately we are working with a transaxle designed to hold 260ft/lb at most from the turbo s.

I broke my turbo LSD transaxle during a second to third gear shift and my car has 327 RWHP.

what broke in it?

sharkey wrote:what broke in it?

Spun the fixed third gear on the pinion shaft which moved it's circlip out of the groove allowing that gear to load the floating gear. The gear was blue when taken apart. I have pictures somewhere.

sharkey wrote:the major weakness in our transaxles is the final drive. the n/a trans has a weaker center casting and is known to break around the rear pinion bearing, this is caused by excess pinion load, the end result is catastrophic failure. the turbo trans reinforced this area, but heavy pinion load can still break it. the reinforcement plate essentially fixes this issue, however it just moves the failure point to the next thing, the ring and pinion. the gearset in these transaxles is tiny, around a 7" diameter ring gear, and the pinion is equally as small. the teeth are small, and just cant take high load.

the turbo transaxle is stronger, the taller final drive makes the pinion gear larger making it stronger in itself. other changes were made to make some of the gears a little stronger. the turbo s transaxle (AOR) is a regular turbo transaxle and had shot peened 1st and 2nd gears added, as well as the input shaft was shot peened, this is for added strength. the lsd also was tweaked for better performance. this is the strongest 944 transaxle out there, however at 500hp/tq id still consider it to be like glass. some people have run them with this sort of horsepower with n/a v8 swaps, however you need to be careful with them. if you try to launch it you will be going home on a tow truck. even with an aggressive clutch if you make a wrong move it could spell disaster.

unfortunately we are working with a transaxle designed to hold 260ft/lb at most from the turbo s.

I read you were looking to build your output up to 600 hp. What are your plans for your trans? I'm willing to be a test dummy for potential swaps as I have absolutely no issue cutting pieces out to make things fit. Please lend me your thoughts on the subject. Thanks.

i eventually want to make around 600hp in my car, but im not running an ls, ive got a gm ecotec, so my 600hp is under 450 ft/lb. the aor may last, it may not, its something ill need to find out. if and when i get to the situation where it doesnt hold, ill cut the car up and put the corvette t56 transaxle and torque tube in the car

Here are a few pictures from my current build where we installed the Corvette T56 Transaxle and torque tube. We actually used the entire rear subframe from a corvette with suspension and all. Just had to custom make the mounting system and where the suspension and rear control arms mounted. As you can see fuel cell fits perfectly where it used to be and is nicely hidden. We are looking for that 600whp mark which is why we went for the T56.

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Jchard944 wrote:Here are a few pictures from my current build where we installed the Corvette T56 Transaxle and torque tube. We actually used the entire rear subframe from a corvette with suspension and all. Just had to custom make the mounting system and where the suspension and rear control arms mounted. As you can see fuel cell fits perfectly where it used to be and is nicely hidden. We are looking for that 600whp mark which is why we went for the T56.

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That looks absolutely amazing. How long has it taken you thus far? It looks as though I will be following in your footsteps.

I wish I could say I did it myself but a shop local to me did all the work. It took one guy roughly 2.5 days on and off to complete the rear end and get everything cut out, lined up, and installed. We are about to start another round on it soon but I will keep you updated on future progress. I'm pretty happy with how everything turned it. Good luck on the build!

Wow! That's awesome!

Great idea and work! This may be in my future down the road, we will see how my 5R holds up!

Incredible job! Way beyond my skill set........

How much wider is the hub to hub distance on that compared to the stock rear suspension? I've looked around and have seen the rear track on a C5 listed as about 5" wider than a 944. Are those numbers off or are you going to be running big flares?

Haven't been on in quite some time so I figured I would give a quick update. Once I got everything installed and running, the LSA V8 ripped apart the stock 944 transmission in just a few test drives (I figured this would happen but just not this fast). So, I ordered a 01E 6-speed Audi trans from Germany and bolted it right in with a few modifications. The best part was the bolt patterns between the two bell-housings were a match. Just needed to make a torque tube adapter and order a custom cv axle (which took 4 months) due to the slight difference in width. All I have left is to install the exhaust out the back and finish the tune. Let me know if anyone has any questions. I'll be checking back more frequently. Thanks.[You must be registered and logged in to see this image.]

Got any more pictures with new trans installed? What Audi does that trans come out of? Great project so far.

Ryan