exhaust idea

[nicholas421]

i had an idea for an exhaust that could be used for both track and street ...see pic. adjustable butterfly valves would channel the pressure either straight out or through the muffler... or a mixture.

another idea would be to apply spring tension on the valves so that high revs (high pressure) would open the valves allowing the exhaust to bypass the muffler.

has this been done?

 

[j14nsx]

IIRC Porsche sports exhausts have valves in them so they are quiet at idle and louder when going fast. Don't know if they're available everywhere but, they allow the car to pass its annual MOT (DOT) test that we have.

 

[Hrant]

Yep, one local guy, Fred Rauch, who runs in NCRC track events has a Porsche Sport Exhaust w/custom switch on his 2001 C4 coupe. The sound is very ompressive; however last time around his switch got stuck in the open position.

 

[4AU4LIFE]

Until I scrolled down I thought you meant look at the pic of your avatar I was thinking, how does that relate to exhaust....

 

[White92]

Do you mean something like this?

http://arospeed.com/product_info.php?cPath=22_43_45&products_id=1393

 

[sjs]

There have been many variations of this over the years, dating back at least four decades and probably more. JC Whitney has offered manual/cable exhaust bypass valves for as long as I can remember. Every kid wanted one "back when", but of course they weren't really much good. I would be surprised if there aren't quite a few much better ones these days, but there is always the problem of tuning, which will be different in "civilized" vs. "race" mode. Personally I'm not sure the difference in power would be worth the hassle or the noise, but I'd like to se it tested.

 

[Hrant]

In this discussion, I believe the application is intended for aftermarket exhausts that may be too loud in certain localities, and certain tracks that have "noise" limits (such as Laguna Seca). Using it on oem exhausts doesn't make much sense to me, but then some of us with oem exhausts have hit the sound barrier at Laguna!

The C4 Coupe mentioned above does have an aftermarket exhaust, and the sound is really impressive with the switch in the open position.

Definitely, tuning is important if it affects HP/torque adversely.

 

[Gerard van Santen]

Definitely, tuning is important if it affects HP/torque adversely.

Isn´t it true that if the switch is closed that it will lengthen the exhaust and because of that lower the HP and affect torque possitively.
And when the switch is opened the length of the exhaust will be shorthened so HP will be higher

 

[Arata]

Suzuki GSXR1000 exhaust valve