m1bjr

Good evening,

I remember the last time I was at CG and perusing the Porsche Chris was fixing up.
Ran it up in the workshop just to hear the noise, and was quite taken by the motorised butterly valves, one in each silencer bank, that opened up the muffler bypass pipes. In this sport mode, it looks as if the rear silencers are bypassed, the sound is incredible and I would imagine there is a small power gain to be had.

After yanking the Invidia bungs out a few minutes ago ready for a rag-around tomorrow, I got to thinking what a neat idea this would be for such an exhaust.

Perhaps a butterfly with a restrictor orifice could be incorporated into the silencer outlets?
Just idle curiosity, but anyone tried something similar at all?
A button to drop noise would be very cool

martin j

I'm sure "Demon Tweeks" or someone like them sell these, it allows competition cars to be run on the road and then as loud as the rcomp regs allow.

m1bjr

Mmmm.. thanks I'll take a nosey
My boss rallies an old BDA escort, and he inserts a pepper pot sleeve in by the silencer inlet.
More holes = more noise / more power!
Looking for a swanky alternative, maybe just to be different

Cant find nowt, just thought a turbo actuator and butterfly might be useful..

AquilaEagle

Would be nice this, probably a PITA to fit

m1bjr

Oh, for sure ian, but its just an excercise in engineering.
However i would be prepared to have a stab on an old exhaust.

Turbo wastegates off a couple of old diesels might be sufficiently strong.

AquilaEagle

I might have an old Amuse "we" could try it on

tiger289

Is this what you are after Clicky

m1bjr

Sort of.
What I actually had in mind was not to simply dump gas out of a stub end by opening a flap, but to still employ the Invidia silencers and restrict them at the exit with a rotary butterfly valve.
I think these would fit atop the silencer exit and would be hidden behind the rear bumber.
Its just hypothetical at present, but if I see actuators and flaps I could adapt I might just have a play.
I'm wondering what the effect of restriction before the split would be.
If this would drop volume or seriously knock power or both.
It would be easier to fit inline, the decat could be chopped back a little or the device welded onto the link pipe.

Mmmmm.. its a big bore and not sure where you would get a scrap device big enough.

Ultra_Nexus

They way i'd go about doing it is by using 2 backboxes.

Like a double single.

Have the valve at the split.

For power, divert all exhaust flow to the cleaner flowed less restrictive baffle.

For cruising, divert to the bunged pipe.

Jobs a guddun