Trackday silencing

[David Thompson]

With its original 6x18" can on, my Clubsport measured 104db at 8krpm (one green light)static at Goodwood. I fitted a Raceco can from my Caterham which has more than twice the capacity being 7x30" in the expectation of getting below the 98db required for a ten car day. However, it only got it down to 102db under the same conditions.
Is there a way of achieving 98db or an I wasting my time?
Interestingly enough, the Raceco can replaced the OE silencer on my Caterham and reduced the noise from 103 to 97.
There is a lot more induction noise from the Clubsport though, and I suspect this is influencing the result quite a bit.

[Josh Smith]

Merlin Motorsport have these....
http://www.merlinmotorsport.co.uk/p1576/MERLIN-MUF...

Might take the edge off

Cheers

[gixermark]

I was generally ~99/100db with a well packed can in the prosport.

I managed to pass the 98db driveby test at donington with one of the bolt in exhaust 'bungs'

you mention doing the test at one green light... it may be prudent to advise the tester your lights are not functioning, and maybe just tickle the throttle up to what is probably more 5-6k ?? very few scruts will know what they are looking at on your dash....

[PaulV]

gixermark said:

I was generally ~99/100db with a well packed can in the prosport.

I managed to pass the 98db driveby test at donington with one of the bolt in exhaust 'bungs'

you mention doing the test at one green light... it may be prudent to advise the tester your lights are not functioning, and maybe just tickle the throttle up to what is probably more 5-6k ?? very few scruts will know what they are looking at on your dash....

A few do...
Anyway in some cases under-reving will give you a higher reading than taking up to the required 7.8k (2nd green light nearly on for those that don't know)

The Merlin Stub is usually good for around 5dB when new, so it is likely to get you under the magic 100.

Don't forget to test with all bodywork on, and with the engine at a decent temperature. That can be good for a couple of dBs

Edited by PaulV on Wednesday 10th February 19:57

[Simon T]

gixermark said:

very few scruts will know what they are looking at on your dash....

Well, I think you have just made some new friends...

IMHO I think you are doing the scrutineers a bit of a diservice, I find them to be pretty clued up and aware of all the 'flexibilty' in the rules

Simon

[splitpin]

Simon, you've confirmed what I thought; that sounds like an experienced MSA Scrut and as you say, they are usually well on the ball; suspicion confirmed when I did a PH search and found Paul putting our Rob right on the statics and drive-bys at Combe back in 06. Would that be Mr Paul Lxxxrxxxx?

Thankfully, not a case of 'Careless Talk Costs Lives', but

[PaulV]

splitpin said:

Simon, you've confirmed what I thought; that sounds like an experienced MSA Scrut and as you say, they are usually well on the ball; suspicion confirmed when I did a PH search and found Paul putting our Rob right on the statics and drive-bys at Combe back in 06. Would that be Mr Paul Lxxxrxxxx?

Thankfully, not a case of 'Careless Talk Costs Lives', but

Nope not me.
A copy of the Radical manuals can be useful now and again.

Simon knows me, and is (almost) always spot on with his beast.

[mabbott]

I'd forget trying to get down to whatever a trackday requires - a combination of dicking around with the hardware required to do it and the pathetic approach to sound measurement you find once you get there. A sweeping generalisation, admittedly, but I used to get so fed up turning up on a track day of having to endure some cock trying half-heartedly to measure something they knew nothing about and the typical 'rules are rules' response if anything looked vaguely marginal. I just don't bother anymore.

In contrast, never had problems at a test or race. Ok, the limit is far higher, and some reassurance to see a measurement procedure adhered to. More generally, I'd love to find out why we even both with a noise test mandated in the way that is (static) which bears no relation to how noise is propogated on the move. If it's just a nod to be seen to be doing something then just fess up it that way and we can treat it the same way...

Rant over...

[splitpin]

Entirely different to our experience over the last two and a bit years.

We did umpteen trackdays in the SR4 at a whole variety of venues from 105 statics @ places like Silverstone to the dreaded 98 static @ Bedford (using Radical's Race or Quiet cans accordingly) and not once did we fail a noise test, including drive-bys; not even someone having a word.

[mabbott]

...which is encouraging to see, so perhaps there are pockets of common sense out there after all!

[David Thompson]

Thanks for all the replies
Like most on here I've had mixed experiences, but Goodwood is the most difficult, and I guess I just have to go elsewhere or pay the extra for a 5 car day. It gets a bit lonely though, I prefer being in a bit of traffic. To give them their due, Goodwood tested my car specially for me, and knew more about it than me ( i believe the track day instructor runs a Radicl team?) I don't think I'll have the same problems at Castle Coombe as they are happy to test at 4500.

[splitpin]

Chief Instructor @ Goodwood co-drives a rather special Rad with another very quick & trophy laden Rad Pilot. Like you, all ROC Members.

[martvr]

David Thompson said:

I don't think I'll have the same problems at Castle Coombe as they are happy to test at 4500.

Afraid they don't, they test a Radical as a bike engined car at nominally 75% of red line. I've found some confusion with this in the past as they apply the same limit of 100dB whether it is a 4,500 rpm test on car engined cars or 7,500 rpm(ish) on bike engined cars. And the scrutineer understands the Radical dash lights.

The confusion? They run bike trackdays and test at 75% of red line but the limit mysteriously is 105dB. On one occasion, I checked this with the circuit themselves and went along armed with an e mail from them stating that if it was a bike engined car they would test the same way as a motorcycle with the noise limit of 105dB measured at three quarters of max revs. The scrutineer hadn't been told this however so it became an exchange between the two before I was grudgingly passed (in time to miss the briefing). I don't for one minute expect that they will have changed this and so expect that 100dB will be applied and I can't be bothered to go through this faff each time. They also will not formally allow slicks on trackdays although a chat with the pitlane marshall can sometimes get you past that if you behave on track for a session or two.

[splitpin]

Again, strange that some of us have lots of problems, others have none.

Touchwood that we continue to remain in the latter.

No-one has ever said anything about us running on slicks, not even a funny like don't you think the tread on those tyres is getting a bit past it. Only used treads (i.e. wets) once, the morning monsoon @ Rockingham latter part of last year ........ all who were there will forever remember it well!

[superlight7]

Ah the Monsoon @ Rockingham - remember it well - back there at end of month - fingers crossed for better weather.

[splitpin]

Good luck Geoff ........ take your brolly just in case .......... and your thermals .......... if it's not raining, it always seems to have a cold blow there ........ must be those nearly always empty huge stands

BTW we'll be shaking down just down the road from you on 26 Feb if you find yourself at a loose end.

[Simon T]

Splitpin, are you testing at Silverstone on 26th?

s

[splitpin]

Hi Si

No Snett, to which you may ask why the back of beyond?

We've managed to persuade an indisputably fast & kind chap who lives in the general locality to help us shake it down (actually, the truth is of course that we'll be helping him) and to pilot and ride shotgun as we start to gather some seat time ............ bigger car, bigger engine, way more aero, paddleshift

[Count Johnny]

Snett on the 26th, eh?

Interesting...