exhaust diameter for turbo vq35HR

[fireslave]

Greetings 350z guys!

Ive got a vq35hr than im installing into my 1992 240sx coupe, and im trying to figure out what to do about the exhaust system.

I want to have an exhaust that will be able to handle about 400whp incase i decide to turbo it in the future. Problem is, theres not as much room under the car, so it wont be as easy to run a dual setup.

I was wondering what piping diameter would be the minimum for a single exhaust 400whp engine.

I figure 4 inches would be ideal for a single pipe, but i might not be able to get that to fit. How much HP do you think i would lose with a 3 inch pipe? or a 3.5? I might be able to run dual 2.5's in the stock location if i do enough planning, but im not sure.

I know a single 3" will fit.

[evildky]

dear gor 4" is hugely overkill, for a single turbo on a 3.5 liter 3" pipe is plenty, and if you run dual turbo's 2 2.5 pipes are more than adequate

[fireslave]

sweet, thats exactly what I wanted to hear. everyone always tells me you cant go too big for an exaust system for a turbo car, but i need it to not scrape on the ground!

I'll probably end up merging two 2.5 inch pipes into a 3 inch pipe.

[C-Kwik]

I used a Greddy 90mm exhaust when I had my S14. That's some 3.5" and I didn't have any clearance issues. Mine was only lowered about an inch on each corner though.

And yes, the general rule for turbo exhausts is as big as will fit or your ears can bear. My friend had 2 exhausts for his Supra years ago. The car had an HKS single turbo dyno'd at some 450HP. The 4.5-5" Ti exhaust he had for it yielded quite a bit more noticable power than the Standard HKS turbo exhaust (3.5"?; I don't remember). But is was a huge pain in the ears and with the silencer in, power was worse than the HKS standard. He put the HKS back on as it was unpractical to run the larger one without the silencer and worse for power to use the silencer. Believe my ears. You can go too big...

[terrycs]

I'm running 2.25 dual cat backs on my V36 sedan and making 470 WHp no problem. If you're gonna go with a single pipe, you should be safe using equivalent cross sectional area.