Filip

First, I apologize if this has been asked before. I searched through the larger forums here and couldn't find the answer to my question. I did learn a lot about other unrelated things tho Anyway, let me give some background to my question.

I am a mechanical engineering senior at UT and I'm [in the process of] designing a scratch-built coupe. It will have a tube frame chassis, rear/mid engine layout, Kevlar reinforced body, etc. Building this will be my major project for the next few [many] years. I have decided on either the 930 or 915 transaxle (G50 might be out of my budget) and have not narrowed down my engine options very far. Finally, my question:

I would like to transplant an AWD Porsche drivetrain, if it is possible. I would like to stick to something a little older. I realize the newer traction control / stability systems rely on a box full of sensors and pre-programmed vehicle data. Can you recommend and models/years that have reliable all wheel drive? Even better - has anyone performed a swap/transplant that you know of? Any other misc suggestions?

TIA everyone. And again, I apologize if I sound rather ignorant - my experience with Porsches is limited...

DangerIsland

asking the 944 board is sure the wrong place not that we won't try to help, but since the 911 is the only car that porsche ever put an AWD system in (if my offhand knowledge serves me right) they might have some better answers for you.

The idea of a light handbuilt Midengine/AWD coupe is pretty wild, hope that works out for you.

I always thought that a midengine RWD custom car with an Audi/VW 1.8T tuned to the teeth would be awesome. Avoid all the hassles and weight of AWD and use an engine that's proven itself to be tunable and reliable.

Or buy a 914.

Hans

Hi Filip
I have played with the idea to convert an Audi 80 Coupe to all wheel drive in the past using the drive train from an 4-wheel drive sedan.
Both were from the late '80-s, no fuzz, no electronics, just (gleason / thorson) diffs and an open dif on the front wheels.
Project never realy got started... Got married instead...
Might want to shop around on Audi / VW forums, search for Synchro and 4-motion.
TakeCare

EDIT:
DangerIsland: FYI, Porsche used to build a vehicle called Jagdwagen in the late 50's, based on 365 technology.
AWD all-terain car, looked something like the VW 181. Like the Lamorgini LM series: very luxurious and very fast (for that time).
Monday morning wake-up thought: Cayenne is an new idea or just new technology in an old idea?
TakeCare

jim968

I'd strongly expect that you'll find Porsche parts to be scarce & pricey. You'd be more likely to get to your goal using AWD parts from a more common & cheaper brand, like Audi, Subaru, or a RAV4.

If you use anything recent as a basis, be aware that systems are becoming more and more integrated... things like ABS & AWD & engine control units being interconnected, sharing information, etc., so you're more likely to have to use only the engine & brakes that came with the AWD system, and have all the electronics from the same car.

It sounds like a much fun project... be prepared for a lot of educational experiences as you proceed.

Jim, "Where are we going, and what's with this handbasket?"

924Superwagen

One thing you will have difficulty with is finding a vehicle that wil allow for this layout. Take a Subaru for example... the entire engine is located in front of the front axles to allow for the front driveshafts. The only vehicle that I can think of that is mid engined and AWD is a Lamborghini. What I wold suggest is to look at how the drive train is laid out and get some ideas. Apart from that, a great source for parts would be an old quattro system as it is almost entirely mechanical and not integrated into Engine management systems, traction control, etc. But, if you are up to the challenge I may be interesting to be able to modify these systems.

Good luck... I was, in fact playing around with the idea of building a mid-engine 1.8T-powered sports car, but only RWD. I'm only a first year Mech Eng student, so it's going to have to wait for a while.

Filip

Thanks for the input everyone. DangerIsland, I'll repost in the 911 forum per your suggestions. The 911 was the only one that I found with the quattro system installed, but I thought that I just didn't do all of my homework.

jim968, the reason I am not considering Subaru and Audi is vecause they are all front-engined cars. AFAIK, I would have to flip the engine around north-south. This way the former 'front wheels', are now the rear wheels. The problem with this is that I'd now have 5 reverse speeds and one tall 1st gear I suppose machining a custom gear assembly to reverse the rotation would be possible, but maybe rather expensive? And what happens if it breaks?

Two of you mentioned the 1.8T. This is something I've never considered before. I was thinking of something like a 3.4 modded out (port, turbo, etc) to get about 400-450HP. Also there are tons of adaptor plates for the Porsche transaxles, so I figured I could use a LT1 or even SBC (although I'd have to alter the sound) if I wanted.

Thanks again,
Filip

ThE sPaCeCoWbOy

how are the Eclipse GS-X's laid out?

do they have the engine in sideays with the shaft going to the rear wheels from the side of the tranny?

you could do something like that but then again, you want mid engine....you would have to make this rear unless you make a box....

space

BartW

I had a GSX and the engine sits sideways in the front, it has a driveshaft to the rear that is directly in the center of the car, the AWD is bolted right to a FWD style tranny and runs the shaft to the rear wheels. I sold mine pretty cheap, the best thing to do is to find a smacked up one for around $1,000 or less and if you want power, the Mitsu turbos are cheap (under $1,000 for a 20g which is wicked) all you need are larger injectors and the turbo and a pump that will supply enough fuel for a reliable 450hp setup that will cost less than $3k.

MM951

Just so all of ya know, Porsche expirimented with an AWD 924...I can scan the article in Chirstophrous (sp?) for ya guys if ya want...

sweanders

[quote]Originally posted by Mike Markota:
<strong>Just so all of ya know, Porsche expirimented with an AWD 924...I can scan the article in Chirstophrous (sp?) for ya guys if ya want...</strong><hr></blockquote>

I want!

sweanders

If you use a transaxle from a 924/944/968/928 that already has the gearbox in the rear - shouldn't it be poissible to middle mount the engine in the chassis and shorten the connection (don't know the english word) betwen the engine and gearbox?

The you would of course need to make/modify a shift linkage so that it will go around the engine... But hey, if you use a tiptronic or auto gearbox you should be able to run a wire connection to the shift lever, maybe you could do that with a manual as well but the feel would probably be terrible... Or install a small electrical servo controlled with buttons on the dash..

Hans

[quote]Filip: The problem with this is that I'd now have 5 reverse speeds and one tall 1st gear <hr></blockquote>I once re-assembled the tranny from my good old Beetle and found just that (as per murpy AFTER everything was installed): had the diff gear wheel on the wrong side of the pignion....
So to invert you need to make a mistake...

There was a good all wheel drive lay-out for military trucks, originally designed as conversion for RWD to 4-WD.
You might want to try this link for more detail:
<a href="http://web.inter.nl.net/users/bravocie/" target="_blank">http://web.inter.nl.net/users/bravocie/</a>
Select YA-328, scroll down till you find the exploded view. (The text is in Dutch, but has minimum tech content anyway)
The power train parts are orange.
You find one central diff behind the chassis cross member, with short shafts to two difs along side. Then transaxles to both front and rear.
All difs were open, with mechanical lock-up (1930 technology!!), could be changed to LSD or gleason as required.

I think this sort of set-up is possible with Quattro parts. Their rear suspention was basically a copy from the front.

Alternative could be full hydraulic, you then also have the ultimo auto-trans: constant varying ISO steps and the built-in ajustable LSD, range 0-100%
TakeCare