Trackday Silencers...

[zacherynuk]

Hi two quick questions regarding these, specifically the ACT £62 ones...

a) Do they change the note / musical range of the exhaust at all ?
b) How long do they last ? (Or are materials now good enough to really work and last...)

Cheers

[Mr Supercharged]

To add to this, how good are they, how many decibels do they drop the sound level?

[450Nick]

Mr Supercharged said:

To add to this, how good are they, how many decibels do they drop the sound level?

They are great, though they probably won't work too well on your car being supercharged. I used to have a set and they worked great in getting my car on track despite ACT sports decat manifolds and the cherry bomb exhaust. When I put the charger on though I found at Brands Hatch that it passed the DB test, but when going past the pit straight it would suddenly become very loud indeed.

It turned out that they have an upper limit of gas speed at which they are effective, and once the gas speed goes past that, they don't really do very much. So I sold mine and had a re-designed set made which use a bigger perforated internal bore, but over a longer silencer. I had the two straights at the back of my exhaust cut off and then had a set of normal 40cm long tails made up, and then two silencers which can be bolted in their place for track work / stealth mode. They work very well indeed and bring the DB from 109ish (being careful with the revs) to 102.

In short, the normal ones are fine and great for a standard/lightly modified car - but make it sound a bit inductiony with a very noticeably muffled exhaust note. If you're running more power, you'll need something a bit more beefy.

[roseytvr]

Yep they certainly work and will last you. Mine reduced the noise considerably, much quiter when driving and reduced my decatted system by 8db. The difference between a black and a green flag on a TD. A bhp killer though!

[miniman]

I might have a set in my garage that I no longer need

[QBee]

I have to say I used mine two weeks ago and noticed no change in bhp. Mine got me down from 105-106 dB to 101.2 dB at Snetterton, so about 4 decibels. They seem to muffle the sound a bit, taking the harsh bark out of the exhaust note, and some of the pops on over-run. My systems is fully decatted, Clive Y, standard silencer section.

I would point out that HANDLING, TYRES and BRAKES are what matters on track days, not every last horse. Hence why we can get monstered by bloody Caterhams on cornering.
At Snetterton I was chased by a TVR with 90 fewer horses than mine, and struggled to shake him off, except on the straight, and that's not really the point is it?

Get you car 4 wheel geo'd (and corner weighted if possible) if you haven't already - you will be amazed how much better it handles and how much faster you can take the corners.

[Mr Supercharged]

450Nick said:

Mr Supercharged said:

To add to this, how good are they, how many decibels do they drop the sound level?

They are great, though they probably won't work too well on your car being supercharged. I used to have a set and they worked great in getting my car on track despite ACT sports decat manifolds and the cherry bomb exhaust. When I put the charger on though I found at Brands Hatch that it passed the DB test, but when going past the pit straight it would suddenly become very loud indeed.

It turned out that they have an upper limit of gas speed at which they are effective, and once the gas speed goes past that, they don't really do very much. So I sold mine and had a re-designed set made which use a bigger perforated internal bore, but over a longer silencer. I had the two straights at the back of my exhaust cut off and then had a set of normal 40cm long tails made up, and then two silencers which can be bolted in their place for track work / stealth mode. They work very well indeed and bring the DB from 109ish (being careful with the revs) to 102.

In short, the normal ones are fine and great for a standard/lightly modified car - but make it sound a bit inductiony with a very noticeably muffled exhaust note. If you're running more power, you'll need something a bit more beefy.

Hi Nick, good to hear from you. Have you got any pics of this please. Thanks...

[pwd95]

They are a very good bit of kit, have a pair myself. Used them on my old Griff 500 & on my old Chim 430 (both with sleeved pipes) They do knock a few bhp off mind, but you won't notice on track.

[seeby]

I use a pair of motorbike silencers . They are small enough to slide inside the Tiv pipes . They get the sleeved noise down enough for Mr noise tester & no noticeable power loss . And they only cost about 20 quid

[450Nick]

Mr Supercharged said:

Hi Nick, good to hear from you. Have you got any pics of this please. Thanks...

Hey, yes I've been lurking more these days as works gone a bit crazy, how's your car running these days? Not many useful ones at the moment as I'm nowhere near my chim, but here is a pic of one of the silencers!

[Mr Supercharged]

450Nick said:

Mr Supercharged said:

Hi Nick, good to hear from you. Have you got any pics of this please. Thanks...

Hey, yes I've been lurking more these days as works gone a bit crazy, how's your car running these days? Not many useful ones at the moment as I'm nowhere near my chim, but here is a pic of one of the silencers!

Nick, same here I'm afraid, been all over the country working on outages at the Nuclear Stations. Car is actually going quite well, thanks for asking. Sat in the garage waiting to be driven. Still on the C30-94, would like to go bigger, but I figure with road use only what's the point. On road tires it struggles for grip up to the legal limit in the dry. If you're ever Gloucester way give me a shout and I'll buy you a beer. Just bought a vaux red top for the westfield, going to build a supercharged motor with that and then swap the motor but that's another story. Thanks for the pic, do you still go to austecs? How are the guys there? I believe Ash has moved on, is it Tom now on the rollers?