98 db(a) noise level

[pincher]

Hello chaps. I am now preparing for my first track day (Donnington 16 oct) and I understand its a 98 db(a)noise limit. The rules say it should be tested from 0.5 meters away at 45 degrees at 2/3 of max revs. What am I going to claim is this rev range ? I have 98 decibels @ 3300 revs. Is this going to allow me on the track in my 1700 crossflow? If not, whats my best course of action ? cheers Ian.  

[conibear]

You will probably get tested somewhere between 4500-5500rpm  

Unfortunately, you will need a track friendly silencer, like 6.5" or 7" in diameter and as long as you can physically fit. Once you achieve that then you need to consider driveby levels and induction.

Sorry for the bad news

[pistonbroke]

AFAIK

If you somehow get past the static test and allowed on trackthere is a trackside noisemeter will pick yer row up and you get sent off for the early bath  

If that happens you lose yer dosh too  

[pincher]

You will probably get tested somewhere between 4500-5500rpm  

Unfortunately, you will need a track friendly silencer, like 6.5" or 7" in diameter and as long as you can physically fit. Once you achieve that then you need to consider driveby levels and induction.

Sorry for the bad news

Is that the 2/3 revs.?

[Man On The Clapham Omnibus]

4,500 is 3/4 of 6,000 (or 2/3 of 6,750). The former is the norm at some tracks at least.

[Mark Stanton]

The drive by noise test at Donington can be quite strict       earlier this year there were quite a few sevenesque kits that got thrown off    

[Man On The Clapham Omnibus]

If you know where the drive by tester is can you anticipate it and back off a tad? Better than forfeiting your dosh.

[adhawkins]

If you know where the drive by tester is can you anticipate it and back off a tad? Better than forfeiting your dosh.

Ummm...going on a track day and then lifting off every lap sounds like you're missing out on the whole point of a track day.

Safer to cancel (and presumably get some sort of refund) until you're sure you can pass.

Andy

[pincher]

I've got a couple of weeks to get it sorted and there's a lot of options, going to try longer, reversable silencer first. thanks for all your help. Ian.

[pistonbroke]

What exhaust you runnin ? Is it a re pack jobby ?

[pincher]

It will be from friday, 22"x5" from Deemon tweeks.Hope it works, actually,I hope it fits. My old one is probly as old as the car (91) but is 24"x4".Other problem is 103db(a) of induction noise at air intake, Got to make a cover over carbs. Ian

[pistonbroke]

It will be from friday, 22"x5" from Deemon tweeks.Hope it works, actually,I hope it fits. My old one is probly as old as the car (91) but is 24"x4".Other problem is 103db(a) of induction noise at air intake, Got to make a cover over carbs. Ian

make sure you pack it with the correct  fiber stuff it makes a big difference IMO

 

[pincher]

I'm hoping it comes with the correct fibre stuff. Mmmmm. food for thought. b******* now I have pre-empted setbacks.Ian.

[felters]

Sorry to p*** on your chips but I'd be surprised if you got a xflow to 98db with your new can. My maths are crap so I can't figure out the volume of your new silencer but I'd have thought you'd need something bigger and longer to get a xflow down to 98db... Raceline, Raceco, Wunoff are people to speak to.

Co-incidentally I'm doing Goodwood today - again - and have a Raceline silencer. 30" long, 7.25" diameter and yes it did involve new headers and chopping the rear wing to get it in, but it's the only way to be sure.

[Toby Mack]

my can is 5" by around 22" and just gets by xflow below the 98 limit, but it does need to be repacked quite often to achieve this.

You might well be ok, although a larger one would certainly be a better bet.