Sound Testing

[frosty]

I saw someone testing sound at the exhaust of different cars during tech. I didn't get to talk with him, but I thought that, as he does his testing, he should look at things like:

Big block vs small block
NA vs Turbo
Low red line vs high red line

Just my two cents added to a debate that already has $10 in it.

[woodrufj]

It wasn't testing the cars, he was experimenting to see if we can develope a coorelation between his in tech test to actual on course sound.

Jay W
505/287 Dakota

[frosty]

Well... taking measurements from cars.

I'm all for it if he can do it. It means two more people who can be picking up cones per run group (or possibly doing 8 run groups with fewer people?)

[Mazda_Gremlyn]

I doubt the two extra bodies would be enough to change the run groups back. Besides, you'll have the naysayers complaining that people can change their sound equipment after tech and still be over our "limit" on course :rolleyes:

[frosty]

Besides, you'll have the naysayers complaining that people can change their sound equipment after tech and still be over our "limit" on course :rolleyes:

Eh, true. It could be countered by taking digital pictures of the exhausts on each car going through tech (to be used incase someone protests it), but now we're talking about three times as much work at tech.

[MX5bob]

Eh, true. It could be countered by taking digital pictures of the exhausts on each car going through tech (to be used incase someone protests it), but now we're talking about three times as much work at tech.

Tech doesn't really need more to deal with. And more important, the method of measuring sound on course is mandated by the city.

[woodrufj]

The point of the experiment is not to change our methods. It would be nice to have a corralation of on course noise to in paddock noise. Then when someone makes changes, or brings a new noisyish car they won't have to take a run to find out they're too loud. We're talking one or two cars a day, not every single one of them.

In my opinion, we aren't going to find a formula to upscale paddock noise. Depending on design and mods unloaded engines sometimes make more noise, sometimes less, some the same as loaded engines.

Jay W
505/287 Dakota

[cshodges]

Do you think there's enough room in the new trailer to pack a dyno? :D

[RandyC]

Tech doesn't really need more to deal with. And more important, the method of measuring sound on course is mandated by the city.

There are things that can be done to make this easier for tech, and the method we use for measuring sound was not mandated by the city.

[froggy47]

Just as a "data point" I was measured @ 96 during the tech "experiment", and as most people know have never has a sound issue on course. I think maybe have had reading of low 80's on course - varies from event to event due to location of meter & wind/weather etc - but that's another thread. Stock aftermarket GM licensed (80 lb!) ss exhaust system.

Steve said he was using the CHP method of testing, so I hope I never get stopped by them & put thru a sound test, I guess I would fail.

:)

[frosty]

Well, he was testing at 3 feet as opposed to 50 feet. So you having 96 db is no surprise.

[MX5bob]

There are things that can be done to make this easier for tech, and the method we use for measuring sound was not mandated by the city.

So, it's our method. Hmm, if it's our method what stops us from changing it?

[MX5bob]

Just as a "data point" I was measured @ 96 during the tech "experiment", and as most people know have never has a sound issue on course. I think maybe have had reading of low 80's on course - varies from event to event due to location of meter & wind/weather etc - but that's another thread. Stock aftermarket GM licensed (80 lb!) ss exhaust system.

Steve said he was using the CHP method of testing, so I hope I never get stopped by them & put thru a sound test, I guess I would fail.

:)

Well, first the CHP doesn't actully do the testing. If you're ticketed for loud exhuast, you're sent to the referee. Second, the test is an SAE method.

[woodrufj]

So, it's our method. Hmm, if it's our method what stops us from changing it?
Nobody can agree on a better/more consistant method.

Jay W
505/287 Dakota

[MX5bob]

Nobody can agree on a better/more consistant method.

Jay W
505/287 Dakota

Ah, of course.

[RandyC]

So, it's our method. Hmm, if it's our method what stops us from changing it?
Nothing. I think that is why we are looking at options.

Have you seen how other (non-SCCA) clubs police their sound levels in San Diego? :)

I know some have some disagreement with changing, but there are some positives in a different method.

[froggy47]

Well, first the CHP doesn't actully do the testing. If you're ticketed for loud exhuast, you're sent to the referee. Second, the test is an SAE method.

Heck, that's worse. That means if Officer Bob say's I'm too loud, then at the very least I will have to spend 1/2 a day submitting to a state employee's scrutiny of my car. Wonder what else he'll "observe" while he checks my exhaust noise? Tires look a little bald Froggy, nah - they're DOT legal sir.

:)

[MX5bob]

Heck, that's worse. That means if Officer Bob say's I'm too loud, then at the very least I will have to spend 1/2 a day submitting to a state employee's scrutiny of my car. Wonder what else he'll "observe" while he checks my exhaust noise? Tires look a little bald Froggy, nah - they're DOT legal sir.

:)

Yeah, exactly. And I've heard of cops ignoring the piece of paper you get from the referee and saying you're "too loud" by their subjective perception. It's complete bull**** of course.

I recently saw a SDPD "training" film on spotting illegal modified cars. The officer involved in its production supposedly knows what he's talking about, but based on the film I'd say he doesn't know his ass from his elbow. The Civic used in the film had an MSD ignition box. Too bad for the film's makers that ALL MSD products have E.O. numbers from CARB. The film also says that modfying an exhaust is illegal, but that is patently false.

So, if you're stopped by SDPD and many other agencies, expect ignorance. :mad:

[Beeasti]

Don't feel bad with the 96db. My car measured a 106db and I haven't had any issues on course!

[Bimota Guy]

Well, he was testing at 3 feet as opposed to 50 feet. So you having 96 db is no surprise.
20" at 45 degrees off axis of the exhaust. And at 60% of redline.

Most interesting data point from my testing was BLB's RX-8. That car recently got popped for noise and the pre-fix test recorded ~100 dBA. Then after the fix the reading was 90.4 dBA. I got ~93 dBA. Same RPM...5,400.

So, who can send me a copy of the sound sheets from Saturday?

[woodrufj]

I've got them. I'll send you a copy. PM me the address.

Jay W
505/287 Dakota