Exhaust Size Query

[rb240z]

Hi guys,

finally had my engine swap work done to my '71 240z,

Have put in an rb20det w/gearbox, cooler, eng. management system, surge tank, fuel pumps

Looking at getting the exhaust done for it in the next few days and am curious on any thoughts in regards to a size.

I'm thinking 2 1/4 - 2 1/2", with a hi-flow cat and effective muffler. I've had a couple of friends tell me to go 3", but i'm not convinced its going to really help the performance of the car, moreso just making it louder than i want.

Have had a search through the forums with not much success, sorry if i'm repeating a gone over thread.

Any advice on this would be greatly appreciated.

Thanks again

[R31Nismoid]

3" all the way. 2 1/4 is nowhere near enough.

Back pressure is the enemy of turbos. 3" and be happy

[skybarge]

yep fully agree

3" is best, a 3" will sound nicer, deeper, it won't be louder if you do it right

Put in 2 mufflers, or a muffler and a resonator, one just after the cat, one at the end of the car

It'll sound very nice

[TailsTails]

3" will drone like a m$%()#*(er, I'd be going to a good exhaust shop and saying "i want maximum power for minimal drone". 3" is very hard if not impossible to stop droning, it'll give you headaches, did in both cars i've owned with it (and this one is only a catback). imho

[mad082]

3" will drone like a m$%()#*(er, I'd be going to a good exhaust shop and saying "i want maximum power for minimal drone". 3" is very hard if not impossible to stop droning, it'll give you headaches, did in both cars i've owned with it (and this one is only a catback). imho

there is this new invention called mufflers. if you get good ones they will cut the noise and drone. get a good centre muffler and a nice oval muffler on the rear and it should be all good.

[TTT]

yeh.. cat, resonator (subaru guys use long truck mufflers as resonators to quieten them down without the restriction), and large body rear muff.

[BAMR33]

Bit off topic, but what brand resonator's do people use? I mean theres plenty of info on mufflers but resonators seem to be lacking on info like cfm flowed and noise reduction. Anyone recommend one?

[rb240z]

Thanks for all the quick replies!

looks like i'll be going a 3" w/ a hi-flow cat and couple of mufflers!

[mad082]

Bit off topic, but what brand resonator's do people use? I mean theres plenty of info on mufflers but resonators seem to be lacking on info like cfm flowed and noise reduction. Anyone recommend one?

trying to find a good 3" resonator is hard. most are too skinny through the body. just get a 3" off centre-centre oval muffler put in the middle, then a either a straight through 3" oval muffler on the rear, or a 2nd off centre-centre muffler for the rear.

[grandmasterb]

3" all the way. 2 1/4 is nowhere near enough.

Back pressure is the enemy of turbos. 3" and be happy

meh stock cat back FTW :laughing-smiley-014:

Its worked wonders for me and my sleeper

[R31Nismoid]

3" will drone like a m$%()#*(er, I'd be going to a good exhaust shop and saying "i want maximum power for minimal drone". 3" is very hard if not impossible to stop droning, it'll give you headaches, did in both cars i've owned with it (and this one is only a catback). imho

Maybe dont be a tight ass and get a decent exhaust made?

Mine have never "droned" and they were 3" 3 times, and soon a 3.5"

[GeeTR]

Drone is a resultant from harmonics down the length of the system. Proper resonator / muffler choice should eliminate drone in ANY pipe size.

SMB are really popular in the rotary world, were a 3.5" system, comprising of SMB cat and muffler, bring 400hp turbo setups to legal limits, with no drone.

[Beer Baron]

also the wall thickness and material of the pipe used has a bid effect on the sound and any harmonics (drone). generally mild steel is sold in thicker pipe than stainless and the mild generally sounds a bit nicer with less resonance.