Graham,
This is a long but 'must read' Pelican article on a 3.2 -> 3.5 conversion.
Note it is a 1988 thus G50 box though.
http://forums.pelicanparts.com/showthread.php?s=&threadid=181728
Part II is here :-
http://forums.pelicanparts.com/showthread.php?s=&threadid=186906&perpage=20&pagenumber=1
Here is the opening post
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Well,
Summer is unofficially over in Southern California and it's now time to take the 3.2L motor out of the car for the performance rebuild. The motor has 88K on it and is being rebuilt due to one or more bad valve guides. Will know soon enough how many are bad (or even if the problem is the guides!!!). Car has intermittent blue smoke at idle (not start-up). Will go for a couple of weeks without smoking and than for a day or two spews blue clouds of smoke at a light. My guess is that the valve stem seal is moving around, which is why the smoke is so intermittent. Oil consumption is still 1,400 miles a quart which is acceptable.
The car was on the dyno (Dynojet) today to get a baseline for the performance improvements to follow. With a Steve Wong chip, Dansk premuffler and Dansk 2 out muffler, the motor made 3 runs total. The first run saw 197 rwhp and the two subsequent runs saw 198 rwhp. All numbers were SAE corrected. Max torque was 182. Seems to be in the ballpark what other people are getting with the same/similar mods. Kudos to the gentlemen who got 219 rwhp with similar mods. I'm not even close but I guarantee I will surpass that with the new motor!
We than took the motor out this afternoon, transported it to my buddie's machine shop and placed it on the engine stand. Tomorrow I will remove the exhaust, the Motronic injection and see how far I can get into the longblock. Bear in mind that my friend and I are doing this after hours.
This will also take alot longer than normal because I am writing a series of articles for European Car Magazine detailing the build and options that are available to SC and Carrera owners. Basically every thing I do I have to stop and take pictures, both for possible publishing for the magazine as well as for my own documentation.
What did we find while removing the motor? The first thing we noticed that will need replacing is the clutch slave cylinder. There is a small whole in the rubber boot that pisses fluid when squeezing it. Next thing I found is when the rear swaybar was being removed one of the rear swaybar mounts is beginning to crack. They are the original mounts as far as I know, but they are also the reinforced versions. Last, after removing the transaxle from the motor, it looks like the main seal is beginning to weep as well. Everything else external seems to be in good shape, we'll see what things look like internally in the next few days.
The 3.5L motor has the following specs:
100mm Mahle Piston & Cylinders (MI/Carb Piston shape)
10:1 - 10.3:1 CR (goal)
993 Twin Plug Distributor with ANDIAL Motronic Signal Splitter
ARP Head Studs
ARP Rod Bolts
Web Cam 20/21 Camshafts
AASCO Performance Valve Springs
Extrude Honed Intake Plenums
Bored out Throttle Body
Magnecore 8.5mm Twin Plug Wire Set
Boattailed Engine Case
Polished (not ported) Heads
European Racing Headers by George Narbel
Dansk 2 in 2 out Stainless Muffler
Custom Steve Wong Chip for Twin-Ignition
Hardware/Sheet Metal powdercoated, cad plated, etc, etc
The motor is destined for street use with limited track days and thus will retain the std. Motronic and will run using our pathetic 91 octane available in California. Other than the headers (which the stock heat exchangers can easily be refitted in a couple of hours), the motor will be CA smog legal. The heat will be gone but the a/c will be retained (the wife will drive the car from time to time and she insists).
I will post some pics from time to time as things progress but I also have an agreement with the magazine and thus they have first rights for publication. I can only post pics that won't be used for publication. Since the "before" and "after" dyno charts will be published, I can't post the "before" dyno graph from today. Since I am also doing this afterhours, I can't spend a bunch of time on the computer loading images. Posting progress for the most part will have to do.
I know some of you are probably saying to yourselves why bother with a 3.5L from a 3.2L when you can just transplant a 3.6. The answer is two fold: I wanted the original engine case for the car and the cost for me to build this motor is WAY WAY less than sourcing a used 3.6L and conversion pieces. Thanks to European Car Magazine for helping to make this happen.
Special thanks to Vision Motorsports in Laguna Hills, CA for dyno time, engine removal and storage of the car for the next few weeks/months.
The goal for the project is 280 FLYWHEEL horsepower, or 238 rwhp if you use the 15% driveline loss that everyone seems to use. Why 280? Because with 3.5L, that is 80 horsepower per litre which is approximately what Porsche's most powerful street engines put out. The 87-89 Carrera only puts out 67.8, but the 2.7 RS puts out 77.78 and a 3.6 Varioram puts out 79.17. If I can get in the same ballpark as the latter two I will be quite pleased. Will provide plenty of punch even for my 2800 lb. Carrera.
Will I get there???
Ralph
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1988 Carrera w/ 3.5L Twin-Plug
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ATB
Ian