• Registered: 2009-05-27
  • Posts: 322

Topic: 92dB/50'/WOT Sound limit questions

Two questions:

Is the spec "A" or "C" weighted? It makes quite a difference. We used a Radio Shack SPL meter to check our sound level. It's fine "A" weighted (84dB), but is very close to 92dB "C" weighted. I know that "A" weighting is more common. It rolls off in the low frequencies, which obviously car exhaust has in abundance.

Also, the spec says WOT, but is the test really done at redline with the car stationary? It's pretty hard to test WOT with a car that isn't legal on the street.

I searched and didn't find this addressed before.

Near-Orbital Space Monkeys
#528 BMW 528e 121hp Black "Saturn 5" Rocket car with orange foam flames. Sold.
#71 Yellow Fox Mustang. For sale.
  • From: Charlotte, NC
  • Registered: 2009-05-01
  • Posts: 113

Re: 92dB/50'/WOT Sound limit questions

You're putting to much thought into it.  Nobody tests the cars for specific sound pressure measurements at the race.  The rule is in place to deter people from running megaphone type exhausts that are obnoxious.  Like Jay says, run a cherry bomb or something like it and you'll be fine.

Mike
Lab Rats Motorsports
1988 Mitsubishi/Dodge/Fiat Colt Carpocalypse Edition
  • From: Solon, OH
  • Registered: 2009-05-10
  • Posts: 28

Re: 92dB/50'/WOT Sound limit questions

But make sure it works. We probably wasted a good 2 hours over the course of race due to noise issues during the night part of the race. At the time I was a little annoyed there wasn't a real meter to measure, but in hindsight we were really massively more loud then everyone else out on the track.