Converting to turbo setup.
Thread Starter
Joined: May 2005
Posts: 795
Likes: 2
From: Midlothian, Virginia
Converting to turbo setup. I want to start off by thanking everyone for their input. I am not new to cars in anyway or even turbos for that matter but I do understand the value in someone who is speaking from experience.
The car is a 1987 Porsche 944 Turbo (951) manual transmission and lightweight. Motor is a 355 LT1 with a CC306 (230/244 .510/544 112 lsa on 1.5rr), comp cams pro magnum 1.6RR, comp push rods and Morel lifters. Heads have been ported and polished by a local machinist. GM dual plane intake with a Holley 4779 750 cfm DP with mechanical sec. Balanced bottom end. The sad part is I am clueless on what pistons are in the car and what the compression ratio is ( I know that will complicate things ) I know the crank and the rods and stock but have been balanced. Car runs great but I am used to the power already.
I have a twin turbo system planned out which consist of 2 - gt35 t4 .68 AR turbos. twin turbosmart 38mm wastegates, and a procharger red race valve and a front mount intercooler. Wastegates will have a 7 psi spring and plan to use a turbosmart boost controller to increase from there. Carb will be modified or replaced with a blow through carb.
My first question actually is about changing the camshaft. I am looking for a good turbo cam that will fit my application but also maybe benefit me better if I choose to switch to a better head. The AFR 195cc have been on my list for some time. Again thanks for your help and please let me know if I am overlooking something.
The car is a 1987 Porsche 944 Turbo (951) manual transmission and lightweight. Motor is a 355 LT1 with a CC306 (230/244 .510/544 112 lsa on 1.5rr), comp cams pro magnum 1.6RR, comp push rods and Morel lifters. Heads have been ported and polished by a local machinist. GM dual plane intake with a Holley 4779 750 cfm DP with mechanical sec. Balanced bottom end. The sad part is I am clueless on what pistons are in the car and what the compression ratio is ( I know that will complicate things ) I know the crank and the rods and stock but have been balanced. Car runs great but I am used to the power already.
I have a twin turbo system planned out which consist of 2 - gt35 t4 .68 AR turbos. twin turbosmart 38mm wastegates, and a procharger red race valve and a front mount intercooler. Wastegates will have a 7 psi spring and plan to use a turbosmart boost controller to increase from there. Carb will be modified or replaced with a blow through carb.
My first question actually is about changing the camshaft. I am looking for a good turbo cam that will fit my application but also maybe benefit me better if I choose to switch to a better head. The AFR 195cc have been on my list for some time. Again thanks for your help and please let me know if I am overlooking something.
TECH Regular
Joined: Oct 2014
Posts: 415
Likes: 2
Good thoughts on swapping the cam. That CC306 will not be turbo friendly. Get the rest of your setup figured out, THEN contact a pro for the cam specs, like Lloyd Elliot.
Your setup will be determined by both your budget and your goals for the car. I am not familiar with those turbos so I don't know how big they are. AFR195 heads are very good. AFR 227's would be better. Depending on your power goals, the stock crank may be fine. However, I would not trust the stock rods to hold much of any boost reliably. You need to replace them, and while you are in there you can see what pistons you have. Likely if you have stock rods, the pistons are stock or pistons not meant for boost. Diamond makes some excellent forged pistons for boost. And you should be able to dial in the CR with a set also.
You got any pics of the car? I always thought a 944 turbo GM V8 would be an awesome project!
Your setup will be determined by both your budget and your goals for the car. I am not familiar with those turbos so I don't know how big they are. AFR195 heads are very good. AFR 227's would be better. Depending on your power goals, the stock crank may be fine. However, I would not trust the stock rods to hold much of any boost reliably. You need to replace them, and while you are in there you can see what pistons you have. Likely if you have stock rods, the pistons are stock or pistons not meant for boost. Diamond makes some excellent forged pistons for boost. And you should be able to dial in the CR with a set also.
You got any pics of the car? I always thought a 944 turbo GM V8 would be an awesome project!
Thread Starter
Joined: May 2005
Posts: 795
Likes: 2
From: Midlothian, Virginia
These pics are kinda old. Have new tires, motor was pulled and cleaned up and resealed. Oil pump pickup welded on. Motor mount fixed. Clutch replaced. New lifters. But it shows the concept. Any recommendations for a cam ?
TECH Regular
Joined: Oct 2014
Posts: 415
Likes: 2
As far as the cam goes, trust me, you really need to figure out the rest of your setup FIRST, and then get a cam spec'd for you. Variables such as what heads you will keep, what the actual CR is ect. will make all the difference in getting a perfect cam that makes the car run at its peak performance and a cam that may the car run lousy and leave a lot of power on the shelf. Do yourself a favor and get it done right. You'll thank yourself later.
