What Exhaust Size For What Power

[MYP16]

Hi all

I'm wanting some expertise advice on what size exhaust I should be running for the expected power output of my fresh engine

Car is R33 GTR

Forged RB26

Ported head

HKS 272 deg cams

2860-5 turbos

Walbro 460 intank pump

1250cc injectors

Power FC

Xforce dumps

Into 2.5 front pipe that goes to 3 inch

Into 3.5 inch decat

Then 3.5 inch tomei Ti expreme titanium catback system

Hoping for around 600hp at the treads.

Would this exhaust system flow enough ?

On another note

I hate the sound of my exhaust while moving. Sounds great on idle but the moment the foot goes down it sound like a dirty Na VL with no exhaust. Will adding a high flow cat help ?

Thanks in advance

[stealthfoz]

id probabably upgrade front pipe to 3.5" aswell.

i have rb30det, 500rwkw with 3.5" turbo back and no restriction problems at this level.

have just upgraded turbo to push the old girl a bit harder, will see how far the 3.5" can support

[XKLABA]

Only thing i will say is lose the X force dumps, these are a direct copy of the HKS ones are they are only an improvment over stock R32 dump pipes, get some thing with 3" outlets and then a front pipe with 3" inlets and 3.5" outlet to match the decat

[MYP16]

Thanks guys

[MYP16]

Adding larger pipes and a high flow cat will quieten it down a bit?

[scotty nm35]

Adding larger pipes and a high flow cat will quieten it down a bit?

No.

[r32-25t]

No quieting it down is the mufflers job

[jjman]

its your mufflers and resonators that change/reduce the sound mostly. Though for sure a cat convertor will also help certain types of sounds too.

Sounds like your issue is more around the muffler and resonator side of things though.

[jangles]

Changing the material of exhaust will change the sound a lot.

[JustinP]

What power level would usually warrant going to a 4" exhaust (4" all the way from a single turbo setup)?

[jangles]

General rule for least restriction is;

300kw = 3"

350kw = 3.5"

400kw+ = 4"

Less restriction the better though

[WARLORD]

General rule for least restriction is;

300kw = 3"

350kw = 3.5"

400kw+ = 4"

Less restriction the better though

4" for 400kw +

ive seen a race car do 440kw with a 3'' front to back

[jangles]

Yep, and if you read the whole thing...less restriction is best... Not 'it won't do it with any other size'

Guaranteed with a bigger exhaust that car would make the power on less boost.

[bigmikespec]

General rule for least restriction is;

4"

Less restriction the better though

'no exhaust'

that's better

[Hadouken]

I can almost guarantee you that your annoyance with sound is due to the front pipe. Google equal length front pipes (ie mines) and see how they sound.

[WARLORD]

3.5 inch is fine

[MYP16]

With front being stainless or to small ?

[33GTRV]

If you plan on staying with low mount twins go out and get a good exhaust. CES do a good dump and from there go a good cat and muffler and 4". Do it once and do it right.

[WARLORD]

Only thing i will say is lose the X force dumps, these are a direct copy of the HKS ones are they are only an improvment over stock R32 dump pipes, get some thing with 3" outlets and then a front pipe with 3" inlets and 3.5" outlet to match the decat

With front being stainless or to small ?

as Xklaba said

[XKLABA]

If you plan on staying with low mount twins go out and get a good exhaust. CES do a good dump and from there go a good cat and muffler and 4". Do it once and do it right.

This, i have both types of CES dump pipes, factory type on my R32 with matching CES front pipe and comp series dumps on my R34 with custom twin 3" into single 4"

CES have the best split type dump pipes on the market and IMO the comp series are better then bellmouth type pump pipes