Quiet silencer for a Clubsport?

[PhilboSE]

Hi all, acquired a nice little Clubsport recently, as soon as the BJ trailer arrives I'll be off for some trackdays.

However, at the moment it has the race silencer which the docs say is about 108dB. For places like Goodwood and CC, I'll need something down to 98dB. I know that Radical themselves offer a 98dB silencer, but I was wondering if anyone else has any tips for a source of a quieter box?

Also, when tracking a Radical, are there any sorts of spares above the obvious that I should be considering having to hand?

Cheers

Philbo

[gridgway]

That was the same question I was going to ask. I went to CC today confident that I could hit 100db as I had my brand new "trackday" SR4 type box fitted to my clubsport. Unfortunately, I could only get down to 107.1!! With a Merlin Motorsport dongle on the back I got it down to 104.5. Unfortunately I didn't take the race box with me to try (why would I, with a new super-quiet box?!).

The factory is a bit confused about it and is going to replace it as it should be much quieter. However, my guess would be that a new one will be the same.

Can anyone add anything to this?

Re spares, I haven't worked that out yet, I am not sure I would be changing much if it broke at the track, but maybe things like a throttle cable. Brake pads?

Graham

[gridgway]

BTW Phil, which Bj trailer are you going for?
Graham

[jimg]

The first time I repacked a silencer myself it increased the noise rather than reducing it. The problem was that I had packed it too tight. If whoever packed it used too much wadding (i.e. a piece cut for a bigger silencer) it could cause this.

[gridgway]

could well be. It's not repackable as such and I don't know if it is made for the job or modified from some other application.

It's pretty heavy, so perhaps I should compare the weights of the one that is going back with the replacement one.

Thanks
Graham

[PhilboSE]

Hi Graham

I've actually got a "custom build" BJ trailer that they liked so much the spec of that they've now decided to make it a "standard"! My particular issue is that I have a double garage with 2 6'6" openings that are considerably narrower than the 7' standard width single garage.

It's a variation on the TT20 model in their line up, with 4 small fat wheels underneath the beavertail flatbed. The bed is only about 1'6" off the ground apparently. BJ are doing a nice "package" with the trailer consisting of a folding towhitch (new, stronger design), 2.5m ramps, the best hitch security lock they offer abd some other bits. I've also elected to have a low-level wheel rack that also has slots for 3x20 litre jerrycans. It's a 14' bed, 2000kg gross 1350 load weight. As they're going to offer a "standard" trailer just like this (albeit a 13' bed), they very kindly did this for me for a "standard" price rather than a custom one. Overall I've been very impressed with all aspects of dealing with BJ and I'm well pleased to have gone with them.

I'm getting it at the end of June, can't wait!

I'm also still investigating 98dB silencer options. I've heard from a few sources that the Radical 98dB silencers aren't. As the whole point is to get something that can pass the Goodwood & Castle Coombe noise police, I have to be sure that it gets under the limit. I'll post back if I find anything.

Phil

[PhilboSE]

The other thing about silencers and noise is that of course it depends on the angle, distance and throttle level of the test itself. I've passed static tests in the past only to fail drive-by tests in the Elan.

[orangeradical]

what i thought about doing in the past is to use the original motorcycle silencers, in the case of a clubsport/sr4 kawasaki standard silencers which must be available from motorcycle breakers/ebay?it must be straightforward to fabricate an attachment and brackets,possibley even use two if there is the room within the frame?

[gridgway]

Will the original bike box be any quieter? I assume (although have no real idea) that the mods to the engine to get the power make it much louder than in the original bike form.

Graham

[orangeradical]

i cannot imagine that the engine mods will make the engine any louder, possibley with the exception of flat slide carbs and the intake which may well increase the induction noise, but one thing i remember from goodwood a few years ago when i owned a clubsport was making sure that the engine was really warmed up first, once the engine is at running temperature the noise level actually reduces. the other issue will be the fact that at a static noise test the microphone must pick up more than the exhaust because all the engine noise will be funnelled under the bodywork and out at the rear. the goodwood readings were something like 105dba static but only 87dba on a drive by!!!

[gridgway]

I am not sure what the mods are between the road and Radical versions of the engine, but agressive cams with more overlap and different cam timing (esp on the exhaust) side def affect noise levels.

Bit depressing if there's no hope of getting below about 105 though :-(

[PhilboSE]

Interestingly this link:

www.radicalextremesportscars.com/racing04/bulletins/08_2005_t.php

suggests that Radical *are* pretty confident that their quiet silencers will pass the CC noise limits.

[gridgway]

good one. I wonder if there is more than one quiet box?

[gridgway]

Phil, just had a thought re Combe. As far as I know, the silenced test days at CC are a 105db static noise test, not the 100 that they have for their normal track days. Maybe not that re-assuring.

More work to do I reckon.

Graham

[vic silvey]

I use a clubsport for trackdays and you will have problems with the quiet tracks. My car is fitted with a Radical (I think) re packable quiet silencer and an extra baffel which you fit up the end of the exit pipe. I bought the baffel from Donington circuit they sell them to the Bikers who are too loud. Even with all this you will struggle with the static test if you are forced to use 34 max revs. On track the best thing is to find out where the noise meters are and back off or short shift as you approach them. This worked for me at Goodwwod and Donington. Good luck,I hope this helps.

[master_328]

I have a shark titanium exhaust with silencer mounted at the moment, but I think it is not quieter than before, I just didn`t like the factory silencer, since the aluminium tail breaked away all around the pipe and it is 3 times heavier than the titanium unit.

[Ravon]

Did a sprint at Goodwood a few weeks ago with my Prosport, fitted with a freshly packed Radical "low noise" silencer and got through the static test by the "skin of my teeth". On drive-by the car was really silent. But getting through the noise test by the skin of my teeth is not satisfactory, my guess is that Castle Coombe would be impossible, and Donnington under the new regime would be difficult.

I've asked my friends at Raceline Cars if they could get one of their Caterham Seven style repackable silencers made by Cheeseman for my car, this would be 8 inch diameter instead of 6 inch and about 5 inches longer. Will keep you posted.

Tim