all custom exhaust!

[ribbed4hr2]

Ok here is the deal my girlfriends father builds racecars and he's gunna help me make custom headers i pipe the whole works. my question is what would be the ideal set up (pipe size ect) for the whole thing i was thinking 2.5 from each head to a 3in colector and 3 inch all the way back what do you guys think. we also are gunna look engineering a custom set for turbo but alot of people have not had luck with the 3.8 so who knows but this guy is awsome.

[Patrick Javert]

No, No, No. don't get 2.5" primaries! that's overkill. At most, get 1 3/4" primaries. that's plenty big enough to get all the exhaust out of the heads. hell, some ls1 users say that going 1 3/4" primaries are overkill for their cars too unless you have forced induction or NO2. the cylinder volume for our cars is .63 liters, the ls1 v8 cylinder volume is .7125 liters. I say get 1 5/8" primaries, then merge them into 2.5" collectors, have a high flow cat mounted to each header, and then run 2 2 1/2" I-pipes w/ and x-pipe crossover just before the rear end, 2 s-pipes going over the rear end, and then have it go straight out whatever tips you want. One thing that is a must, all of the exhaust piping has to be MANDREL bent, no crimping the pipes whatsoever. why, crimping makes the pipes smaller inside and they don't let as much air through. mandrel bends keep the pipes diameter the same throughout. This setup is basically a true dual exhaust setup. I'd say you could run a supercharger and no2 at the same time with very little restriction. I must warn you, however, that you will lose a fair amount of low-end torque by doing this on a naturally aspirated engine, but the top end will be a lot stronger and you will be setup for a sc to be put on.

[ribbed4hr2]

see thats why i ask.
well i would hate to loose all the topend but true dules sound appeling. all the pipe will be manderlen bent so thats not a prob. what do you think that yould sound like. has anyone ever done any thing like this?

[ribbed4hr2]

We have been kicking around the turbo thing what are some big problems people have run into? on the 3.8

[Patrick Javert]

I've only heard of ls1 owners doing it b/c they are gettine a sc or boring/stroking out their engines. The main turbo probs are whether to run 1 turbo, a twin-turbo sequential setup, or a twin-turbo setup w/ one turbo run off of each bank. main prob for 1 turbo is where to fit it under the car. main prob w/ sequential setup is passing smog. main prob for 1 turbo off each bank is passing smog(not hard to pass if you run cats. after each turbo and have header wrap to get the cats. warmed up quickly) and where to put all the piping as well as either 1 or 2 intercoolers. I suggest w/ what I have suggested getting a 1 turbo off each bank. you will find several turbos set up for imports that you can match to your engine. Find a good streetable turbo for a 1.8 B18C engine(integra/civic engine). you will have to have cutom tuning of your car to make all this work. Engine fortification is a must. This will be a major project, I hope you got the cash to burn.

[ribbed4hr2]

well sounds like the turbo is off. th sc sounds like a better rought down the road. but i do want to do the headers and stuff but till i can fork out the $$$ for a super charger i want a setup that wont kill my low end so any other ideas the dules arnt out just want to get all my options down.

[ribbed4hr2]

any one else?