Decat & trackday noise limits

[Jay Payne]

Does anyone know what kind of difference a de-cat makes in terms of decibels gained?

My car Currently comes in reguarly at 95db. Most Circuits have a limit around 100db but some are as low as 98db so I don't want to restrict myself by making the car too noisy if I'm gonna gain 3-4db by removing the pussy.


Car is a phase 1 172 btw

 

[Daniel]

Can't really answer your question, but 98 is the limit at combe.

 

[Hollister]

You have to remember that its a logarithmic scale, so the difference from 96-98db is more than the difference between 95-97db.

If your car is more than 98db it is loud, and a decat shouldnt make that much difference from 95db

Depends how you measure it too... the MSA Blue Book states a cetain degree and distance under cetain conditions at 3/4 max rpm. In practice noise checks are rarely done to those specs.

 

[Jay Payne]

at Bedford it was done at 4,500 rpm and Oulton at 5,000rpm. it was around 95db at both

I thought it was some complicated maths thing. If u dont think it will be that much of a gain then thats great. Thanks

 

[MarkCup]

I'm decatted and Stealthed Jay...never read above 98 at any circuit so far.

 

[ForceIndia]

TBH at most days I've done, they haven't even bothered testing me, just get the passed sticker. They tend to just let me through, as they can't even tell the Clio's on when it's parked next to a TVR/Caterham

 

[Jay Payne]

I'm decatted and Stealthed Jay...never read above 98 at any circuit so far.

iirc yours was very low at Bedford, in the mid/high 80's wasnt it?

 

[Jay Payne]

TBH at most days I've done, they haven't even bothered testing me, just get the passed sticker. They tend to just let me through, as they can't even tell the Clio's on when it's parked next to a TVR/Caterham

They didnt test anyone at fcs (as far as im aware) but msv seem to be quite hot on it

 

[Bazzon]

Dont think yours is as loud as ours burp, ours is decat powerflow ect. Easily passes the 98 Db s at croft.

I am more suprised yous still has a cat.

 

[Jay Payne]

I am more suprised yous still has a cat.

Lol, all in good time

 

[Ex-User (19928)]

98db is double the volume of 95db. Can't see removing the cat making that much difference tbh.

 

[Jay Payne]

^ Great thanks. It will be coming off soon then

 

[Hollister]

It's a stupid test really as the noise a car makes stationary at 3/4 max revs bears little resemblance to the noise it makes flat out under load with the induction and transmission noise thrown in

 

[Peperami]

It's a stupid test really as the noise a car makes stationary at 3/4 max revs bears little resemblance to the noise it makes flat out under load with the induction and transmission noise thrown in

Until you get black flagged for noise

 

[ForceIndia]

At bedford the drive by is the one to worry about. The R400's were fine, so I can't see 99% of clios having a problem.

 

[Adey.]

mine made it on track at combe, but as mentioned mine seems near silent when not under load compared to when ure actually driving it. decated with a powerflow cat back on mine

 

[Jay Payne]

I thought yours was very loud when i drove it Adey, and that was before the boddies