Chaps,

I'm building my exhaust and a friend is concerned that I'll fail the noise test!!

SVA manual states 101 db at 75% of max revs or 66% of max power or something along those lines.

Exhaust is 1/5" headers into a pair of collectors (one each side) into a pair of 2" pipes (one each side), then into a couple of Cherry Bombs (one each side!).

My understanding is that 101 db is actually very loud.

I need some eg please - ie pneumatic drill is 90db?

Thanks

ATB

Simon

Road rally cars are tested at 98dB at 4500rpm, get down to a local rally and try to have a listern. 101dB is loud!!!

Excellent:-)

Simon,

Have look here http://www.bookatrack.com.

They will hire a digital noise meter for £9 inc for a few days. You can then test out if your system is too load

Click the miscellaneous link at the bottom of the shopping links on the left hand side at the top

HTH

You can't just go waving a sound level meter at your car, and reading the value on the screen.

There are standards writtern telling you how to take measurements, so far from exhaust, at a cetain angle etc etc.

My job is designing sound level meters, and I'm hoping to get hold of the standard if anyones interested.

You can't say 101 dB is loud, it depends on soo many things.

PS, while at Tiger on Saturday I saw their sound level meter which I was told was the same as used at SVA, I had never heard of the make! Look on the back, make in China. No mention of any standards etc. If my car fails SVA on noise I'll start asking some awkward questions

IIRC it's 1 metre at 45 degrees off the exit of the exhaust.

Kingr

If you are building a V8 Locost and going to have an exhaust outlet on each side of the car then you are at an advantage with the "1 metre, 45 deg" rule!

Also Rover V8's, despite their engine size are not particularly noisy, ie don't have that shrill noise of some smaller 4 cylinder cars.

I failed my initial SVA on noise, coming in at 105dba. I debated with myself about challenging the result, ie asking to look at the certification for the meter etc, but decided against it. The examiner had been pretty fair anyway. He told me to stuff some wire wool up the end of the exhaust and come back! I did, and passed at 98dba.

He told me that an Ultima had failed the week before at 115dba - now that is noisy!

Dave, where did you have your SVA? Notts? i failed on noise there too, 105db with a 1300 xflow! standard but on carbs x2, the pipe im using is from stuart taylor motorsport, i was suprised to fail

John, yes it was Notts (Watnall).

I have a home fabricated, 1.75" bore stainless system, it exits at the back of the car, but there isn't much in the "silencer" box!

I'm used to noise testing at motorsport events and to be fair I suspect his 105dba was probably right.

He checked my noise level at 4500 revs and I also considered arguing that this was too high. I have lent my SVA manual to another builder so can't check it, but I recall the rpm level rules being ambigious and felt worth an argument!