Switchable exhaust valves, experience? Input please.

[Butter Face]

I am considering fitting an exhaust system to my car (Supercharged Civic Type R) as it is currently running 275bhp with the standard exhaust (I think it’s 1.75inch) but of course it is quite restrictive and I’ve been told I can definitely gain more power form an exhaust and manifold replacement.

My issue is that I like my car being quiet, I’m too old for a hideously loud exhaust all of the time. I don’t mind the idea of having it loud when I want to go for a drive out somewhere, but I want it quiet when I’m starting it on the driveway at 7am!

So I have considered getting a custom exhaust, likely 2.5in diameter. I like the idea of a switchable valve to make the exhaust Quieter/louder. Like this...



The blurb says..

4mm gap either side - valve doesn't shut fully (this would damage the engine)

So does such a contraption fit like this...

To effectively block off the exhaust and keep it quiet..

Or like this...

Where it would divert gases around a silencer to free up the flow?

Any thoughts or input appreciated!

[Turn7]

Certainly on Muscle/drag cars Ive seen it used to exhaust ahead of the silencer, so creating an effective open header system.....

[stevieturbo]

Just have a decent exhaust made and there is little reason it should be stupidly loud.

[GreenV8S]

Butter Face said:

I’ve been told I can definitely gain more power form an exhaust and manifold replacement.

Let me guess - from somebody selling exhausts and manifolds?

The power levels you're looking at are not especially high in the scheme of things and there should be no problem getting a conventional exhaust system which has an acceptably low back pressure and is reasonably quiet. I don't know where the pressure loss occurs on that system but even quite small changes to the exhaust diameter can increase the cross section area significantly, and silencer effectiveness is primarily limited by volume. Both of these give you scope to reduce the pressure drop as far as you want without resorting to exhaust cut-outs.

[Butter Face]

Actually it was the guy who did the remap, no gain in it for him (except the hours labour to update it once it’s all fitted)

I’ll take your advice on board, cheers!

[witko999]

They normally bypass the silencer with a seperate pipe as per your second drawing. The Porsche PSE system is similar, although it uses a vacuum actuated valve.

I'd be very surprised if a Civic Type R came with a 1.75" exhaust as standard.

[stevieturbo]

witko999 said:

They normally bypass the silencer with a seperate pipe as per your second drawing. The Porsche PSE system is similar, although it uses a vacuum actuated valve.

I'd be very surprised if a Civic Type R came with a 1.75" exhaust as standard.

It does sound very small for anything half modern these days. I'd expect more like 2.25 to 2.5"

[SydneySE]

its taken 10 years for the UK to catch up, but an x-force muffler is your best option- the valve is incorporated in the muffler- it goes from stock sound to sport sound, but never open header loud.

http://www.suttonbespoke.co.uk/xforce-exhausts

just by one muffler and have an exhaust shop fit it to replace yours.

this is the original website, does give more options:

http://www.xforce.com.au/products/universal-parts

(just order a universal muffler to fit)

[stevieturbo]

to catch up ?

Just dont build a st system and it wont need it in the first place.