Gtr 4 Inch Exhaust?

[N1GTR]

Bad thing with the jap exhausts is they're all quoted at the largest point - what they fail to mention is that there's usually a reducer before the muffler. Thats why the local stuff is better - even if it is more costly than the mass produced jap stuff

[Ronin 09]

Trust Power Evolution II is around the $1k mark, I got mine from Croydon.

these are quite loud... i had one, got old and deaf, got racepace item.

[TiTAN]

i have 3.5" from dump back (4"dump) with two big mufflers in it, meets NSW noise requirements and for the most part is custom. most of the jap exhausts start at 3" just after the cat then expand from there and or have reducers before the mufflers (if you want it to not sound like a straight pipe you need lots of muffler a cannon on the back is going to do next to nothing)

i spent a long time looking around for off the shelf options aside from racepace you are pretty much left with giving the car to an exhaust shop (or have a friend that can fabricate it for you) and getting a system custom made with as much or as little muffling as you want in the pipe size you want.

[R31Nismoid]

Problem is giving it to an exhaust shop - it's a gamble.

You ask for a "90dB" exhaust, and they will not take on the job because most have no idea, and cannot give you an indicator of how lound it will be.

What is your exhaust dB level Titan?

I'm assuming it was measured @ 4900 rather than 5100 like a RB26? (the 200rpm does make a difference).

That said I really cannot see a 4", straight through exhaust being legal - ever. It's just too large.

So best option is to get is as close to legal as possible, and therefore less attention.

I'm still looking into options, another option has popped up this week on top of the 2 others... So the GB will go at some point, just have to get prototypes made and try a few different mufflers (which will take a while given it costs $$$).

[TiTAN]

Problem is giving it to an exhaust shop - it's a gamble.

You ask for a "90dB" exhaust, and they will not take on the job because most have no idea, and cannot give you an indicator of how lound it will be.

What is your exhaust dB level Titan?

I'm assuming it was measured @ 4900 rather than 5100 like a RB26? (the 200rpm does make a difference).

That said I really cannot see a 4", straight through exhaust being legal - ever. It's just too large.

So best option is to get is as close to legal as possible, and therefore less attention.

I'm still looking into options, another option has popped up this week on top of the 2 others... So the GB will go at some point, just have to get prototypes made and try a few different mufflers (which will take a while given it costs $).

mine pulls off 89-90db. its borderline but its a pass, the VIC system where it has to be below 91 from idle to test revs and back it wouldnt pass. there is just no way to get a large pipe legal at low revs there isnt enough flow for the mufflers to work properly even my massive mufflers only manage 92-93db at idle.

on the back its a 18"x11"x8" offset -> centre 3.5" straight through and a 10"x8"x5" centre > offset 3.5" straight through in the middle.

the more gas you pump through it the quieter the system gets, there is more road/wind/engine noise cruising around at 3000rpm than there is exhaust which is fine by me.

when i was looking around i was asking about custom made to order muffler sizes it adds a bit to the cost as the mufflers are $250-400 each depending on size and material (stainless vs mild steel) and then you still have pipe + flange + labour costs. the way i look at it the bigger the muffler you can stuff into the masses of space on the back the more ground clearance you can have from the middle one. i really wouldnt be going much more than 5" high in the middle as thats pushing it though.

[R31Nismoid]

mine pulls off 89-90db. its borderline but its a pass, the VIC system where it has to be below 91 from idle to test revs and back it wouldnt pass. there is just no way to get a large pipe legal at low revs there isnt enough flow for the mufflers to work properly even my massive mufflers only manage 92-93db at idle.

89db? Or 92-93dB?

You've listed two different levels and the difference between 89 and 93 is not linear

And just to be clear - you were measuring @ Idle - 1100rpm? Not the "EPA" test of 4900rpm?

What distance was the measure taking? 1m? 2m?

Gotta get specific if people are gonna understand what you mean

You CAN get a 3.5" borderline legal. We managed to get mine down to 92dB @ 5100rpm with a lot of farting around. 1dB off which was a fair effort and that was without any extra baffles etc.

[TiTAN]

89db? Or 92-93dB?

You've listed two different levels and the difference between 89 and 93 is not linear

And just to be clear - you were measuring @ Idle - 1100rpm? Not the "EPA" test of 4900rpm?

What distance was the measure taking? 1m? 2m?

Gotta get specific if people are gonna understand what you mean

You CAN get a 3.5" borderline legal. We managed to get mine down to 92dB @ 5100rpm with a lot of farting around. 1dB off which was a fair effort and that was without any extra baffles etc.

92-93 @ idle (~900)

89-90 @ test revs (~4000) RB25/30 engine so the RTA only asked for test revs for an RB30

standard 45 degree 0.5m nsw rules

i do not have any restrictor plates or other such temporary noise reducers in the system it was taken in exactly how its driven every day

[black bnr32]

anybody run a dynomax vt?

[tk80]

anyone have evidence of a 3.5" system being restrictive on a gtr? and at what power level?

only one i know of was the guy in SA with the 33gtr that put twin 3" side pipes on and gained 80kw.

any other examples? almost giving up on the hunt for a titanium 4".

Edited February 8, 2012 by tk80

[pistol-pete]

Yeah but he was making over 500awkw

[Piggaz]

any other examples? almost giving up on the hunt for a titanium 4".

a mate got a 90 mm system in Ti made for his s15 and it wasnt that much. About $2,000 I think. The guy came out, measured and welded it in a day. I could get the number and more details if you like?

Don't amuse do some awsome Ti exhausts? Not sure if they are quite 4 inch though.

[Deano 1]

I find it amazing how hard it is to find a 4inch off the shelf item when everyone says yu nees one if u plan on making over 400kw.... i mean heres heaps of people making 400kw atm!! Whats everyone using? Shorly not everyone has had a custom 4inch made

[R31Nismoid]

Most people @ 400rwkw don't care about noise.

So ye, most of the time it will be custom with just a rear muffler really. In the grand scheme cost isn't much more over whats already spent.

It's a QUIET 4" exhaust, that's the challenge

[tk80]

i'm at 453awkw on a 3.5" system. will i really get a miracle extra bit of power by upgrading to 4"???

[discopotato03]

This thred is splitting into two with exhausts and turbochargers but exhausts are an interesting topic so maybe I can ad a bit .

I've been researching exhaust stuff for my Evo 6 because I want acceptable road car performance and it has to be QUIET .

Now back to Nissan I was looking at an early Z32 300ZX recently and I was remembering how they had two cats or at least one with two bores through it . By any chance can you splice two cats in before the engine pipes merg into one because if you can each cat is only catering to three cylinders exhausting half as often as the one cat would after the merge . Even if so could have legality issues because I'm told the cat is suppose to be in the std position under the car . Being closer to the turbos they should heat up a little sooner but I guess it all comes back to your and the states interpretations of the laws . These 6.2L Chevs seem to deliver the numbers so they must have something reasonable cat wise - x 2 .

Turbos , my gut feeling is that GTRS GT2871Rs by two would not be ideal things , better suited to a single turbo app where a slight exhaust gas restriction is less of an issue . I don't know if anyones tried the 48 compressor trim version of the GT2871R , GTRSs are the 52 trim version .

One thing I don't think anyones thought of is a version of the GT2860R like a "2530" but with 60 trim compressors . This is what the four cylinder version of the GTSS has and its possible that it would spool somewhere between RB26 GTSSs and RB26 "2530s" while not being that far behind the 2530s .

Personally I think big power in a RB2568cc engine is a useless on the street . You can't use high rev power around the suburbs and if you have to go back more than one gear at highway speeds what was the point ? IMO only two things can pull the bottom end power up on an RB26 without compromising top end power . First is VCT and second is more capacity . There is no easy way particularly as centrifugal turbochargers are a compromise and at best they can span 2/3 of the engines usable rev range . Your call as to which suits you better ie the first 2/3 or the second 2/3 . Other means of airflow control ie variable valve timing DO make a difference but obviously this is not what Nissan was concerned about . They chose to fit GT2556R turbos to late GTRs and even these don't shove you in the back at "normal" revs/speeds .

Anyway your calls , 2530 or GTSS if it was me and twin cats before the merge if at all possible .

A .

[R31Nismoid]

i'm at 453awkw on a 3.5" system. will i really get a miracle extra bit of power by upgrading to 4"???

You are E85 ye?

That does change things a little with how much you can get etc. Same as race fuel does.

Easiest way to tell, drop it from the front pipes.

[tk80]

yep...e85.

[Jap_star]

Don't amuse do some awsome Ti exhausts? Not sure if they are quite 4 inch though.

Myself and Heslo are getting 4' titanium exhausts done from am performance here in sa in the coming weeks. Just waiting on the material. He has done some before but currently not enough stock

[KiwiRS4T]

Can't read Japanese but Mines appear to list a 120mm titanium exhaust for BNR32 or 34 at 270,000 yen

[Deano 1]

Can't read Japanese but Mines appear to list a 120mm titanium exhaust for BNR32 or 34 at 270,000 yen

Interesting, any one read it to us