My Porsche LS1 build

The file I sent was originally designed for an Audi snail-shell (I think).

AUDI didn't make the snailshell Getrag did. This is my snailshell. (G31/02 with EURO ring and pinion and 5th gear)


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huh, I was noticing this different looking transmission case the other day but didn't make the connection. So the "snail shell" is just a tougher casting design that holds pretty much the same internals?

No, completely different internals. Much stronger but has the Porsche balk ring type synchros. (shifts differently than the 016) It is based on the 911 915 transaxle. The ring gear is 7 7/8" in diameter vs the o16 which is 7 3/16" (951 - 7 5/16") The teeth are much wider and taller as well. The gears have a lesser helix angle (less thrust loading)

This is the transaxle that was used in the 924 Carrera GT; GTS; GTR and GTP. (the race car version had an oil pump and cooler as well as shot peened gears and shafts)

I wrote an article comparing the G31 to the 016 series transaxles. If you want a copy I can e-mail you a copy in PDF format.

I'd love to look at that. Thanks! I can imagine it isn't a cheap thing to do, but I can drool about future possibilities.

I had a sears allen key that was 17mm. It ended up being too awkward to use on the drain plug with the trans removed. I cut a 1" tip off the end of the key (so they key was still usable) and stuck the 1" chunk in a 17mm socket on the end of an impact. With 1/2" sticking out of the socket, it works just great!

For you guys who don't live near a Sears, here is the URL for the Hex Key on the thier site.

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If my tool doesn't work when the tranny is IN the car I'll pick one up and maybe do what Porch did

Well,

I haven’t gotten that much done in the last couple of days. I got the front seats all crated up for shipment when they sell, no hurry right now.

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Not a lot of progress has been made on getting the engine out of the car but I did get the front spindles off and and will ship those out for machining before the end of the school year. I plan on using these ball joints: [You must be registered and logged in to see this link.]
So I will need to have the spindles machined.

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Other than that I’ve just had to clean up and hit the books. Probably won’t be a lot of progress until the end of May once school is ended and I have my feet under me again from starting a new internship. I'll miss working on it I really appreciate the help from everyone, let me know if I can help any of you guys out.

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Gt1scca, I didn’t have a trace on paper so I’m going to have to take the case apart again to get that for you. I didn’t have time to do that before I had to head back to school. I’ll try and do that some weekend. I feel kinda bad.

Cheers,

Luke

Hey, I was wondering what those groves that run along the flat face around the middle hole of the adapter plate are for? I'm assuming they're 100% necessary to mill out.

Also: have people seen these beautiful pieces of work?

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Luke714 wrote:I was wondering what those groves that run along the flat face around the middle hole of the adapter plate are for? I'm assuming they're 100% necessary to mill out.

C5 Slave clearance. The base of the housing has a recess for registration on the C5 torque tube. Also, the C5 slave will have to be trimmed accordingly, to sit flush on the plate.

Sounds like BS, but...

The recesses in the plate can be machined as a complete circle, but you will be sacrificing the grip-range of the 7/16-14 set screws in the aluminum. 1/4" deep machining brings thickness of the adapter plate (in the recessed areas) to .400". 7/16" studs require at least 7/16" (.4375") thread depth from memory.

No prob on the Audi plate...
I'll worry about that detail whenever.
"Beegga feesh iz in da pan..."

Hello again,

There was a gap between tests and projects this weekend and I was able to sneak home to work on the car, finally. I wasn’t originally planning on working on the car at all until this summer, but between spring break and the odd weekend here and there I’m definitely ahead of schedule. From experience on other projects though it’s always good to get as much of a head start as possible, because things come up and by the end you’ll be lucky to be on schedule. Also the Cumberland County Motor Club is hosting a whole bunch of great autocross events this summer and I want to make a couple particular events in mid August, I’m not sure if I’ll make it but I’d like to try.
This weekend I finally got the motor out of the car, I had gotten stuff like the radiator out of the car over break but there was still a lot to do. I hadn’t ever taken the engine out of this car, and I haven’t installed/removed many engines at all really so it took me a solid two days. Everything is so packed in it was quite the job; the complicated turbo exhaust system was the biggest pain in the butt. Finally, I got it out though. I ended up cutting some of the exhaust pipes because the bolts were completely froze up.

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Of course the cheap engine hoist I borrowed blew the one way value in the pump, so once it was lowered I couldn’t pick it back up again. You had as much travel as you could provide by just moving the handle one complete cycle. As soon as the engine was sitting on the floor it started working again and I was able to use it to move the engine to the other side of the shop. If you know anyone who is looking for a parts engine let me know, my “sell it” pile is getting pretty high. I’m looking forward to just simplifying the engine bay overall.

SELL IT PILE (gotten much bigger since engine removal, also I'm not selling the front air dam)
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KEEP IT PILE
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I ran out of time but I’ve got to remove the rest of the AC stuff and the intercooler. I’m also moving the window washer bottle to the battery tray and moving the battery to the mid section of the car. Where would you suggest I locate it? Is the spare wheel well too far back? Would one of the back seats be better? Since I’ve gotten rid of the seats it might fit in one of the cavities quite nicely, I would have to take some measurements.

My new Eibach springs, coilover conversions and camber/caster plates also arrived. The torsion bars should be here soon, but they were on back order so who knows. I’m saving up for the big purchase of the LS1 and I hope to have the money for that by the end of May or the 1st week of June. In the meantime I’m prepping the engine bay, getting rid of the unnecessary parts and cleaning, my goal is to have a well organized and bare necessities kind of look under the hood. I’ve also ordered two Corbeau Forza race seats, those are a good deal lighter than the stock heated, electrically adjustable and leather seats. They weigh in at like 18lbs a piece. A roll bar from 928 motorsports is also on the list, just so that I can have a SCCA approved bar. The Corbeau seats are FIA approved. I’ll cover up the holes where the rear seats used to be when I install the new front seats, I might as well steam clean all the carpet too. I haven’t been able to help myself and I’ve been thinking about the little stuff along with the major drivetrain modifications. I think I’d like to try building my own VDO gauge cluster, oil pressure, oil temp, coolant temp, voltage, fuel, tach, speedo and trany oil temp. Well see if I can cram all that into the stock dash space

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Other ideas I had was to use the engine oil cooler off of the old turbo motor as an oil cooler for the transmission, would this work? The only concern would be that the oil pump wouldn’t be able to push enough oil through to make it worth the effort, it might actually cause damage. Looking at the diameter of the stock oil cooler for the trany it seems like it produces a decent flow rate, maybe enough. Thoughts on that would be cool.

I’m selling engine parts as I go to keep a little money flowing back into the project fund, I’ll use that money to buy the little things like SS brake lines, new pads, seat sliders, hose fittings, etc. Hopefully I’ll have enough money from this to buy the exhaust components as well. I’m going with 3” collectors with two spun steel cats into a y pipe and out the back with 3.5” into a Dynatech muffler. Since I’m doing a single I felt 3” was too small if I want to get more power out of it in the future so I went with 3.5”. The problem then was that I couldn’t find a 3.5” cat, so I decided to use two 3” cats before the y-pipe. I think that will actually provide the freest flowing setup as well. Thoughts? I plan on using the flowmaster y-pipe.

I would love to get some advice on the clutch, I have zero experience specing out clutches. I don’t really have any idea how to make sure my choice will fit with the application or what to look for in a kit. If someone could let me know what they use or recommend it would be appreciated, I’ll just go with whatever is most popular with you guys.





Cheers,

Luke

Luke714 wrote:I would love to get some advice on the clutch, I have zero experience specing out clutches. I don’t really have any idea how to make sure my choice will fit with the application or what to look for in a kit. If someone could let me know what they use or recommend it would be appreciated, I’ll just go with whatever is most popular with you guys.

Luke,

SPEC has the best (IMO) clutch disc hub on the market right now. This is not necessarily a biased opinion...The center hub from a 944S disc has been duplicated, and the disc is built around it. No better spline engagement from any Mopar disc, period. They also offer billet aluminum pressure plates, flywheels, and Kevlar discs. Stage 1 - 5 available, even a twin-disc setup. For a relatively stock engine, the Stage 1 or 2 should be more than adequate.

I'm now a SPEC dealer, so check out their 944 / LS1 Conversion Kits and get back to me for a deal.

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Excellent, thanks. The stage 2 (SC092-8 ) with an aluminum flywheel (SC75A) sounds good to me. I'll let you know when I'm ready to order. How much does the aluminum flywheel weigh? I'm assuming that the compound is just organic.

Aluminum flywheel is 12 lbs. / Stage 2 disc:

"Features segmented or full faced pure Kevlar disc with steel backing. This lining features excellent drivability like the stage 1, but offers slightly longer life and higher torque capacity. The hub is double sprung with spring cover relieves for flexibility and heat treated components for strength and durability. Best for street, drag, pulling and autocross.

* High clamp pressure plate
* Pure Kevlar friction material
* High torque sprung hub and disc assembly
* Bearing and tool kit"

thanks, that'll probably be what I go with.

Any thoughts on the oil cooler idea?

I would not use the stock Porsche oil cooler, by the time you round up oddball fittings / hoses to make it work you could have bought a new cooler. I personally like the Setrab plate type. I would not go below AN12 fittings or hose size because of the mass volume GM likes to move ith its pumps.

I am also guessing you could sell the stock cooler to offest the cost of new as well. I looked at a couple 944 turbo coolers, used, and to me thier inlet and outlet sizes seemed restrictive.

Didn't catch if your car was a runner or blown engine prior to the transplant. Another thought is that if it is a blown engine you might have a bunch of crap in it that would not be healthy to a new or even used engine for that matter. Not withstanding the fact that you got around 20 years of potential build up of god know what in it.

My personal rule of thumb = Blown engine replace oil cooler and flush all lines no matter the age.

I'm not thinking of using it on the new engine, but on the transmission. I wouldn't consider it an option for the engine. I normally wouldn't really worry about the trany oil (unless I'm doing some serious RR), but since I have it I thought it might be a cool idea. Would you recommend an oil cooler for the LS1?

On most LS1's you end up with a remote filter, given that add a little extra plumbing and add a oil cooler. I personally think an oil cooler on a sports car is a must. But that is me.

I normally convert the loop type coolers on Porsche transaxles to a plate type, still using the Setrab. Even if it is JUST a trans cooler i would not take a chance with a used cooler. Depending on your level of skill it is pretty easy to make a non oil cooler transaxle into a oil cooled one buy adding an electric pump and using the lower drain plud for the pickup. Then drilling and tapping the rear housing for the return. On the late transaxles the boss is cast in. I would definately suggest pulling the housing to do any machine work. If you want to get crafty you can add a copper feeder to feed the syncros while you got the housing off!

So you don't rely on the pump for the stock loop type cooler? It wouldn't be a problem to wire in an electric pump, however. At what point does the stock loop da loop become insufficient? I'll grab a cooler for the engine, does it matter if it is before or after the filter? probably after, right?

I just wanted to share this build album with you guys. I think this is one of my favorite conversions, love the car. Just wish it was an LS1, not an LT1.

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What's wrong with the LT1?

Nothing I guess. I don't really have any experience with either (yet) so maybe I don't have any basis to have an opinion. It just seems like since the LS1 is much lighter than the LT1 you could have overall a lighter, and therefore faster car. Add lightness.

My LT1 pulls my car just fine, There isn't that much of a weight savings, Nothing a few bucks can't change.