DulinDragons

Im building my B18c1 for boost, but wont go forced induction until a few months after the build. Right now the compression will be 9.0:1. As far as exhaust systems go, im debating between 2.5" or 2.25" I have a set of dc 4 to1 headers going on it also with that 2.25" outlet to the cat. I just wanted to know peoples opinions with the lowered compression and would a bigger exhaust size affect anything. The engine wont be raced on the track till turbo is put on, basically a daily driver also.

TheShodan

iTrader: (14)

Compression can stay stock unless you have a specific purpose
3" exhaust is to be used. If you can only use 2.5" for now, use that.. no need for 2.25, even for NA

You're going a bit backwards on this, but you can get it cleared up.

DulinDragons

well the motor will be fully built before hand with cp pistons, sleeves, and rods. Now i read on here that too big of an exhaust (2.5") would not provide enough back pressure and rob the motor of horse power.

Pleiadi79

yes u are right but i think on NA header config makes difference, at the moment run 2.5" and with the turbo setup a 3" is must

DulinDragons

ok thanks, but i will run a 3" for turbo without a doubt

Pleiadi79

yes u must use a 3" with turbo, if u don't there's the risk of overheating the turbo due to the small section of exhaust.
What turbo?

96 GSR-T

Exhaust size isnt going to matter much, you took the compression out of the motor so its going to be slower NA, I dont think your header and exhaust choice is going to make much of a difference.

DulinDragons

thanks for the advice folks. Oh and i plan on using a gt35, i used a gt2871r with my old D16 setup and i fell in love with ball bearing turbos. The lag is minimal. Last question i have is regarding fuel pumps. I going to install a new fuel tank and add a walbro 225lph pump. Im just doing a bunch of things on this build so i wont have to do it later. Would this pump seriously affect the air fuel ratio, if im using stock injectors and regulator for now until the turbo setup. I dont wanna run too rich yet.