I am slowly rebuilding a turbo system for the 3800 I will eventually be putting into my '89 IROC. When I bought the motor it was a complete motor with turbo etc. When I got it home and started working on it I came to the realization there is no possible way I am going to run the headers or merge that came with the setup. It would have worked, but it was a complete hack job and I would much rather put one together that looks nice.

I have come to the conclusion I will run factory manifolds with a v-band welded on. The problem I am running into is the rest of the system. I found someone local to me that has a really nice merge and intercooler for sale, cheap. I just don't know if it is going to be the best for me. Could you give me some insight into whether or not my idea will work with the parts that are available or should I hold off and go a different route.

Here is the general layout of what I am thinking.

2.5" into turbo (turbo is a cheap t3/t4 hybrid eBay unit in the 64 range), 2.5" out of the turbo into the intercooler, intercooler would be a 3" in/out bar and plate in the 31"x12"x4" range so I will run reducers, 2.5" out of the intercooler into the intake, factory manifolds into a 2" merge into the turbo, then 2.5" DP into 2.75" mandrel bent exhaust.

Again the issue is with the merge/flange the guy is selling and the intercooler.

Hopefully you can understand my ramblings and thanks for any help you can provide.

 

How much power? If under 350 hp single 2.5" dp into 2.75" single exhaust should be ok although it would like 3".

Everything else seems fine to me

 

Power to start will be in the 350 to 400 range. I was questioning the dp and whether to go with 3". It will fit just fine, so I may go that route.

I just did some quick calculations and wanted to make sure my thinking was accurate. There are some assumed numbers here, but you should get the idea.

NA CFM = 5700 RPMs X 231 CI / (1728 X 2) = 381 cfm

LB/MIN = 31.7 (17 psi + 14.7) absolute pressure X 381 CFM X 29 / (10.73 X 590 (130* intake temp + 460) absolute temp) = 55.323 lb/min

Total CFM = 55.323 lb./min X 13.0763 CFP = 723.42 CFM

CFM after intercooler = 723.42 X .85 intercooler efficiency = 615 CFM

If air becomes turbulent at Mach .4 and I decide to run 2.5" piping at 615 CFM that will put me right at Mach .26. The assumed numbers are intake temp, max boost, type of air (CFP), and intercooler efficiency.

This will leave me plenty of room to up boost and/or get a properly efficient turbo.

 

You can force 500+ out a single 3". Thats what i'm doin but it isnt optimal so if you can fit it i would consider it. It wont hurt.