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At What Power Does 3.5 Inch Exhaust Become Restrictive?

usmair

By usmair,
in Engines & Forced Induction

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usmair Mentor

usmair

Posted
Posted

Hello

Considering doing something financially stupid.

I currently have a 3.5 inch on my twin setup.

Was considering going big single and aiming for 550KW.

Does anybody know if the 3.5 " exhaust will hold power back at those levels?

Was doing a budget and wanted to see if I needed to put a $1000 provision in for a new 4 inch exhaust.

Cheers

usmair Mentor

usmair

Posted
  • Author
Posted

i was happy with the power but I think one of the turbos may have let go

only getting 12psi last few days...

this was more of a general wondering more than anything... i still havent actually decided to do it yet lol

was trying to work out how much it will actually cost me

and no this will not be stock internals lol

the accountant in me keeps saying to stop blowing money on this and buy a house but then I sit in a big single with 500kw+ and I just cant help myself!

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

And watch out for the mufflers. Very annoyed to find the 3in tip I bought narrows down to 2 3/4 inside which may not sound a lot but the full 3in would flow nearly 20% more so I am going to have to change it.

Deano 1 Mentor

Deano 1

Posted
Posted

4inch exhausts sound so shtty. The 4inch pipe takes longer to fill with air than a 3-3.5inch pipe. So u don't get that racy sound. U get a deep sound, it can't b changed its because of the muffler sizes and pipe sizes.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

I've driven a few 4" exhaust GT-R's... They sound tough as even with two big mufflers.

But yeah 4" and external screamer would be what you'd do. It'll be less than 10% either way of what it'll cost for 550rwkw so... Not even a consideration really and the least of your money spending concerns.

Deano 1 Mentor

Deano 1

Posted
Posted

It would sound good. You should always have a bigger exhuast closest to the turbos. When the exhaust is hot it needs more room. As it travels down the pipes and cools down it doesn't need the room. So it still sounds good, cause you get thy rushing sound through the 3.5inch section.

I just ordered a 3.5inch tomei ti system. So I'll be Running my 3inxh tuned length fronts, into a 4inch merge, decat that tapers down over 400mm to 3.5inch and than the tomei catback.

I'm interested to compare it to the 4inch system I had on it a few months back. We ran it up o jezza's dyno. So we can almost back to back it.

XRATED Veteran

XRATED

Posted
Posted

Pipe size is all good... alot of this is going to be up to what mufflers you choose to run and or/ any sneaky reducers the manufacturer chooses to put in there. There's not too many true 4" exhausts off the shelf for a gtr.

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