Quieting Down A 3 1/2 Inch Straight Through Exhaust

[gbturbos]

Firstly, for those that care, i havent been on this site since my engine lost oil pressure at 120kmph and became very growly.

It turned out to be the oil pump gear had collapsed.

So, without further ado, the engine was stripped and all damaged parts were replced with mainly hks parts.

The car was also treated to 2 brand new hybrid turbos which were cheap like the budgie wink wink , a "race spec" exedy paddle clutch and many other upgrade parts, chipped and remapped. It was then rolling roaded at 436hp fly 395 lbs torque.

Car has also had full professional respray.

After much head scratching and interesting reading on the net (mainly written by Garrett race research development technicians, i went with a straight through custom made stainless "race spec "3 1/2 inch exhaust which has mandrel bends.

The problem is its loud.

Its so loud that i hate it.

Its horrible on tick over and normal driving, but sounds awesome, like a jet fighter on boost.

My question is

Is there any way of quieting down the exhaust while on tick over/normal driving and let it rip on boost?

Theres got to be something about???????

was thinking a spring loaded flap or similar???

carl

Edited May 25, 2008 by gbturbos

[boliztik]

have u seen those mufflers that have a switch to change between quiet and loud

they alway have adverts in hot4s and hpi if u have any laying around???

[chris_r31]

yer they look interesting, i think its more of a rice thing, for all the lancers with str8 thru systems

and intercoolers sticky taped to there bars, i thought it was for them

[Samon]

two words: XForce Varex

http://xforce.com.au.tmp.anchor.net.au/cars/view_car/29

it's basically a straight-through cannon, but when you close the butterfly, instead of causing excessive backpressure like a plain old butterfly valve would, it routes the exhaust gasses through an extra chamber around the outside of the muffler.

[gbturbos]

not a bad idea, and thanks for the reply, but id rather have something that i wouldnt have to keep control over.

maybe just a normal back box could be the answer

any other idea?

[Yawn]

Those adjustable butterfly valves are shit when it comes to higher power levels. They just cant stay open past a certain limit and keep getting shut when youre on full boost. Which is a disaster waiting to happen

[06tst]

i had one of those Apexi butterfly things which could be adjusted in cabin by a cable wire thingy. It worked but restricted power so I had it disconnected.

My brother opted for a second 3.5" straight through muffler mid way and that has helped bring noise and cabin drone down for idle and cruising but still barks on boost.

I might do the same to mine as it pisses me off too and im not touching those shitty butterfly things again.

[2BNVS]

the varex mufflers work totally different to a basic butterfly... the butterflys can never 100% shut as then there is no where for gasses to go, the varex works differently as the butterfly valve is designed to re route the gasses to pass a few times threw different channels before venting outside... i know a few big powered gtst's that run the varex without any drama's, but the old fassioned basic butterfly valves i would stay well away from

[R31Nismoid]

Well i would say put mufflers.

Any mufflers would be better than none.

Ive got two mufflers, 3.5" exhaust, and it'll flow over 350rwkw without even a sniff, and its as quiet as a mouse, almost like standard GTR @ idle

Its not hard if the person making your exhaust is good at it.

[BHDave]

+1 for a big rear muffler.

You will not make the car quiet while you have a 3.5 cannon on the back, even with a decent mid muffler

I have a mid 3.5 muffler and a massive rear muffler that i pinched off an old Jasma stamped exhaust. It's quiet enough that i can hear all the other annoying noises my car makes while i'm driving on the freeway. I previously had a 3.5 cannon and it sounded great when winding it out through the gears but just too loud on cruise.

It has unfortunately lost the fantastic sound it used to have, but i can drive it now without worrying about police in the next suburb knowing i'm on the way.

[Ronin 09]

i would prefer the varex is in the middle muffler. the varex on the end is visible and EPA might not like that...

oh and 3.5" with big mufflers and all i hear on the freeway is the bloody RE55s... outside the car is a nice note still though.

[gbturbos]

thanks for the replies and comments guys

this board is actually more helpful than my native uk GTR owners board...tut tut....

thanks aagain

gonna go with large last muffler i think

[TiTAN]

16" long offset 3.5" truck muffler. Wont look particularly pretty but it will keep the noise down and for track days and such you can just unbolt it and put the cannon back on.

[coakman]

Those Varex mufflers must be good - the Australian government's banned them (and any similar devices):

http://www.gtrydaz.com/home/Under-the-Bonn...ow-ILLEGAL.html

They'll be enforcing it from 1st Sep.

[R34NRG]

two words: XForce Varex

http://xforce.com.au.tmp.anchor.net.au/cars/view_car/29

it's basically a straight-through cannon, but when you close the butterfly, instead of causing excessive backpressure like a plain old butterfly valve would, it routes the exhaust gasses through an extra chamber around the outside of the muffler.

would be a good idea if it came in 3.5 designs and not only in 3"

[nizmonut]

4 inch turbo flow mufflers, similar to a coby, but instead of using perforated tube it uses cheese grater like tube that draws the gasses to the side of the chamber, instead of relying on the gas pressure to force the gas through the sides.

the do not restrict the system as you can pick up the muffler and look right through it but two of those should get it down to 80 odd decibel