SLR noise level?

[Jas]

I have just purchased my SLR :-)

 

I want to take it to the Lotus track day at Bedford on the 17th, and understand that there's a very strict noise limit (105db?).

 

Does anyone know what the noise level is for an SLR with a straight through cat replacement pipe?

 

Thanks,

 

Jas

[Nick Green]

Jas, 105db is pretty generous! smile.gif Unless your silencer is knackered, you should be all right.

[Gridgway]

My SLR was at 105 with its knackered standard box. If you have access to a noise meter you can measure before you go. If the box is more than about 18-24 months old it could be knackered. I got down below 98 with a new SLR race box, but you should be ok if your standard box is still stuffed full of stuff! You can take it off and turn it end for end. If its knacked you cane hear the stuffing slipping from end to end.

 

ANyway you shoudl have waited for my R500 - fully silenced for all eventualities! :-))

 

Graham

[Drumster]

Jas, I went to Bedford Aurodrome last month and I thought the noise limit was only 102db, so it may be worth checking with them to get the exact figure.

 

Chris Alston

 

Se7ening - it's all miles and smile.gifsmile.gifsmile.gif

[Jas]

Nick, thanks :)

 

Graham, the car is about 8 months old so the box should still be ok. I was originally keen on the R500, but kind of went off the idea as I read more about the car. Sorry.

 

Chris, Lotus (who are arranging the day) have confirmed 105db in writing. The day should be interesting as I'll up against all manner of Lotus'. It'll be the only 7 there, and unfortunately driven by a new owner so i doubt I'll give a good account on the day.

 

Jas

[Peter Carmichael]

Tut, tut!

 

Not *up against* but *amongst*.

[Brad Tipp]

I went to Bedford the other week on an Autocar evening with Honda. The noise limit was 105 static. I a had to back off a bit after the drive by limit was exceeded (bloody roller barrels :-))So if need be don't go balls out immediately after the tight left hander at the end of the pit straight, as that's where the drive by noise man stands.

 

Only other issue you'll have is that anything really quick gets away on the 1KM long straight. However EVERYTHING else was passed on the interesting bits :-)

 

Do remind them that other cars will need to lift, not just pull over, on the straight to let you past. This allways goes down well at the pre match briefing :-)

[Jas]

Peter, "amongst" it is then :-)

 

Brad, thanks for the advice and tips. However, I guess I'll be taking it a little easy as I'll only have driven the car for 4-5 days by the time I attend the track day.

 

Jas

[Andy Checkley]

I often drive at Goodwood and the noise limits there are often a problem. Goodwood ask for 3/4 maximum revs which is 6,000rpm in the SLR. My results have stayed constant at 103db with the standard 6inch box with the Cat fitted. With a rear exit box I got 87db (I think 93 drive by). I have just fitted a 7" side exit with the cat bypass and although I have not had it checked yet I am told it should be about 101-102db.

 

Incidentally, the rear exit box does sort out the noise problems but I removed it because I could not get the pipe that joins the side and rear boxes far enogh away from the rear tyre. On hard cornering the near side rear rubs the exhaust pipe even with a 1 inch gap and a reletively stiff ACB10.

[greg]

Andy,

 

What are the limits at goodwood ?

 

Also is the 7" a racetech ? What do you think of it ?

 

Greg, Q 880 RAE (Green/Ali XF)

[Mike Bees]

Noisy (5 cars on the track at once) day the static limit is 105db at 3/4 max rpm. Quiet (10 cars on the track at once) day the static limit is 98db at 3/4 max rpm. I'm not sure what the drive-by limit is (think it's 101db on a noisy day), but it's complicated anyway because the installed monitoring system "averages" the noise out. Think of it as a bucket with a hole in it - you can pour stuff (noise) in at varying rates without overflowing the bucket, e.g. you can lob a whole load in quite quickly as long as you then trickle it in for a while afterwards. When the bucket overflows the bod in the local council office spots it on his display, gets into his little white van, drives to the circuit & closes it down. Sadly this is the price we have to pay for the Goodwood Revival Meeting.

 

Mike

[Andy Checkley]

Mike's right about the nature of the drive-by at Goodwood. I was pulled off with everyone else recently when I was running in the same session as an R500 and three other cars, although we all past the static 105db.

 

The new 7" is a Caterham race silencer, which I have been able to stretch the 6" silencer guard around as Caterham don't make a guard for this. It looks ok and hopefully will reduce the noise a bit. I am down at Goodwood again shortly so I will post the new noise level at 6,000rpm.