mmporsche

Hello from Denver,

I just picked up a beautiful 1991 964 Turbo last week and have a few questions/looking for advice.

1. It has the stock 17" cup wheels. Is there a general size spacer people use to push them out closer to the edge of the fenders?

2. The car is all stock, however, the seller had a custom Garrett Turbo from a 3.6 and the matching exhaust. Other than some "basic fabrication", according to the seller, it would just bolt on and really improve the power. Anybody else tried something like this on here? Any risk of damaging anything? Would this require anything else to make it work properly?

3. I also hear that people install a heavier spring in their waste gate? I am showing .7 bar under full load. I assume this may allow more pressure to build-up?

I'll post pictures once I can take it somewhere with a nice backdrop. My alternator bearing is beginning to fail and the fan blade is hitting the housing intermittantly so I don't want to drive it until I get it fixed later this week. The wait is killing me.

Thank you in advance!

mmporsche

Pre-purchase

MeanMachine

Beautiful car, I have seen only garrets under turbokrafft efi builds other wise the 3.6 comes with a KKK turbo like the 3.3 and the turbo is the same for 964 if memory serves me right. You only see .7 bar because that's what the screen maximum registers. You need an aftermarket boost gauge to determine the boost under load.


Congrats and hope you have a great experience

Metal Guru

Bigger turbos and heavier wastegate springs do only one thing - deliver more mass (air flow) to the engine. The problem is that unless more fuel is added to the air, lean running and engine damage will occur. Your stock boost gauge will read .7 bar because that's all the max that it will read. You could be very well be running a lot more boost then indicated.
Do not drive your car until you can get it to someone that can measure the air fuel ratio (afr). Go to a dyno and don't let them rev past 5000 rpm. If it's running lean, proceed to a leakdown check of the engine (if this was not done as part of a PPI).
Get your checkbook ready too; the engine might already be trashed.

mmporsche

To be clear, the bigger turbo has never been on this car. The dealer I bought the car from had it and suggested it would make a nice addition. The car is all stock and was owned by a doctor for the past 15 years if memory serves.

I did have a thorough PPI performed and the car came through with flying colors minus a torn steering boot.

Metal Guru

You have two potential paths:
(1) have the dealer re-install the stock turbo
(2) Be prepared to spend time/money on tuning if you want to keep the Garrett

mmporsche

I will say it again, the Garrett has never been on this car. It was for a 3.6 the dealer had previously.

I appreciate the advice, however, I think I am going to skip the turbo change and sell it in the parts section....

TT Surgeon

I'd leave the car bone stock, except for possibly the exhaust, why take a chance?
You could mod the 964 beyond belief and it will never be as fast as your 996ttx50 bone stock.

Metal Guru

With enough money and time, a modded 3.3 would kill even a new Turbo S. Extracting 700+ hp has been done by a few. Also, the 964 chassis can easily shed 200 lb to bring it down to 3000 lb. I don't think the 996 can get there without a extreme measures like carbon fiber body, for example.
Start with a stock engine, drive the car for a while and then decide where to go from there.

mmporsche

I would like a much louder and nastier exhaust note - I don't care if I **** my neighbors off. What's the proven setup without getting into headers?

MeanMachine

What I would suggest is a cat bypass pipe either from fabspeed or cargraphic. boost spring (.9 bar would be ideal) i.e. running .9 bar and headers.

ralt

Question 1) you can put about 5 or 6 mm spacers on each wheel hub. Larger and you will need to get longer wheel studs. The wheel off sets are the key info to moving the wheels outward.
2)You need to find out exactly what "Garrett" you have and what exhaust system you have. Then find a Porsche shop , not dealer, who knows what he is doing if you want to install the parts. How many miles on car or currently installed turbo?? They all wear out at some point/. Maybe save Garrett until needed.
3) Get a boost gauge installed first so you can see whats happening. You can always add a 1 bar boost spring. Would not recommend any stiffer boost spring. The more you boost the engine, the more you wear it out.
PS.. there is a lot of good advice on this forum but remember.......its the INTERNET

KaiB

Wanna bet?

urquattro20Vt

A Denver guy - nice!
Looks like you pretty much have your questions answered. IF you're going to skip headers and are okay with annoying the neighbors (and keeping Advil in the glovebox (from what I hear)) you can do both cat and muffler bypass. I've personal opted for just the cat bypass and like the sound a lot.

We should grab a lunch or beer and talk 964 Turbos.

cash92104

I agree with TT Surgeon, leave it stock! If you really want to upgrade I suggest finding a shop that has experience modifying these cars and take their suggestions... or buy a 996TT.