Noise Limits

I have a bit of a problem! Booked a track-day to show some Audi chaps how a proper car should perform around Castle-Coombe, and find that the noise limit is 100dB. Does anyone know what the noise level should be (The car is a MY2003 facelifted 996 C2 Coupe with standard exhaust) According to Goodwood 2 weeks ago it was 102dB, but that seems high for a standard exhaust - Would have expected 98dB Any thoughts or suggestions on how to reduce the noise level? Gary

Make sure the car is upto operating temperature, by letting it tick over for ages or take it for a quick blast b4 the noise test. Hold the clutch out when noise tested, also you can whizz some sound deadening material over the engine and under the lid -don' t forget to take it out b4 you go on track. Bare in mind that the weather and barometric pressure ALSO make a difference. You should be fine for Combe, if I could get my 964 C4 on to a 100dB day! Mel

The reading on my C4S at Goodwood was also 102db at 5,200 rpm with the quiet button on (107db on sports). The other thing to do at Castle Coombe on a 100db day if you have a new(ish) car is to fib about the rev limit, say your still finishing off the running in and only using 6,000 rpm, a bit of red tape on the rev counter at 6k will convince the marshall, they will then take a noise reading at 4,500rpm (75% of max) which will be much quiter than at 5,200. That' s what I' m going to do on the 19th to ensure I get out. Regards Kevin Cooke C4S XL

Spot on Kevin, put that red tape on rev counter at 5000 rpm,' running in' , that reduces test revs to 3750ish, noise objective is to get below 4. Push clutch pedal right in like Melv suggests. 996s are not expected to cause noise problems, which also helps the cause. Not like 964RS cup cars which are expected to be noisy.[ ] To justify this evasive sort of approach, track days are not so much about maxxing the motor, IMHO its about smooth driving and developing cornering skills, there' s no necessity to redline at 7200 or hit 150mph before the end of a straight, so you are not really looking to make the car ' shout' are you ?[8|]

Thanks Kevin & Oldtimer, I think this is the correct approach, you are quite right, it is about me developing my skills with the car and track in a controlled environment. Gary

Just out of interest, how long can you get away with " running in" ? After 10, 20 or 30K they must start to get suspicious. How many engine rebuilds and mods that require bedding in can one man have?[ ] Rgds, Stuart.

Ah, but with the " electronic" display, I do not have to show the total accumulated mileage, so as long as it is the current year model I should be able to get away with it[ ]

I guess a private plate helps here too.

So THAT is what I' ve been doing wrong!! Thanx Oldtimer!! ;-) Melv

As an epilogue to this thread, completed the track day without any noise problems. Marshall told me to set 4500RPM!. Passed noise test at 98.8dBa The marshalls later commented in passing that most " 911" Porsches are very quite on the track, and do not cause any noise pollution. The " strict" interpretation of the limits is reserved for the all-comers track days, where the Nova boys etc. are in attendance.

Gary, I assume that was at Castle Combe on a 100db limit day. Did they ask you the rev limit or did the marshals just call for 4500rpm. Thanks Kevin Cooke C4S XL

Gary, Sorry forgot to ask. Did you manage to show the Audi crew what a proper car could do or did you get blown away by an RS4 or something similar. I assume you were much quicker than any of the TT' s. Kevin Cooke

I did place the red insulating tape on the rev counter, but the marshall just asked for 4500RPM As for the performance, the RS4' s wouldn' t run on the same session as me[ ], one driver commented that he was afraid that it might make him regret his descision to buy an RS4.[&o] As for the session I did run in, no-one actually managed to pass me, (including a boxter) and on one session I think I managed to lap every car, which included several S4' s - enough said[8|]

What is the db of a Turbo with power upgrade?

Richard, With our without the sports Exhaust? If standard I' d guess well below a 100db at stationary test rpm. With sports exhaust I' d suggest a little quiter than my C4S( see note above) as the turbo acts a pre-muffler. Regards Kevin Cooke C4S XL

I have the standard Exhaust + Stainless Steel Exhaust system. I am not sure if the Power Upgrade changes the exhaust.

Richard, I think you have a standard exhaust. The current sports exhausts are very noisey to the extent that they have a speed sensitive quiet period between 30-45mph to enable them to pass German drive by noise limits. 2003 model year sports exhausts also have a quite button on the dash hence my two noise readings. If you are still concerned at meeting noise limits at PCGB track days check various track day websites and just pop along to one near you and ask the marshalls to give you a noise test, most will oblige. Regards Kevin Cooke C4S XL

It will be great if I could manage Goodwood and Castle Combe as these are two circuits I have not driven with my Caterham R500.

Richard, You need to to be quick (to book that is) According to the PCGB website the only Goodwood or Castle Combe day which is not fully booked is on the 23rd Oct. Kevin

At Goodwood it seems that the static test is more rigorous than the drive by. I told them that my GT3 Clubsport redlines at 6,500 rpm and they asked for 4700. I squeaked through at 105db. My exhaust has 100 cell racing cats and not much else!!!! No problems on the drive by and I was not taking it easy. Lots of factors to consider but a warm engine/gearbox and depressed clutch help reduce the noise. Not much else you ca do to reduce the reading. Regards GARY BULLEN