Sound Reg #3 5/22/11

[Rafal-st]

Working with sound for years thought me that location or even amount of humidity in the air can change any levels of sound. loudness is mesure in open environment even wind can change this reading as well. That might explain why some cars have warnings and then notching for the rest of the season. Special when they are on the border.

[jbarker52]

I think it was louder also. But I also think it is the only time the car has hit the rev limiter at PS due to the wonderfully fast course that John laid out and that contributed to the higher reading. Would it help if the direction of the exhaust was pointed down vs to the right? It was pointing directly at the sound eq. I think on a slower course with lower revs definitely makes a difference.

[integra55]

I am still trying to under stand how my car went from 95 db last yr to 104 this year with no mechanical changes. If I may think out loud, with no disrespect to anyone and I applaud you guys for sticking to your guns. My exhaust exits toward the passenger side of the car parallel to the ground, so it was pointing directly toward Teddy and his sound equipment. Does anyone recall if the sound equipment was situated differently last year. Last year when Mark M. drove my car he was no the throttle quite a bit and no problem with sound. If I recall correctly that course was fairly fast up the hill but did not have as long of a full throttle section as the last event. If any of you guys can help me understand what happened, and a possible fix it would be greatly appreciated. I honestly believe the course and the location of the sound equipment (right vs left side) may have been a factor.

could do like some of the SM racers at CMP and have directional tips for the different tracks and sound equipment placement..

[jcox07]

I changed the axle back mufflers to the dynamax ones and that helped a lot on sm12. Thanks for the advice on those mufflers and THANKS to John for a very good track!!!!

[MARKP]

James, I was standing at the timing tent when your car took off from the line. To my uncalibrated ear, it was very loud and I wondered out loud why you had changed the exhaust. Obviously, you didn't but it was louder than I ever remember and I figured there was no way it would pass sound before the reading was ever called out.

I don't know what your exhaust consists of but I can tell you from experience with several cars that a deteriorating catalytic converter can have a big effect on sound and that mufflers with fiberglass packing will eventually "blow out" and get louder. No idea if those are issues with your car but maybe that will help.

We were borderline with the Miata at local events all year last year and put a glasspack in after the cat for this season that has helped a ton.

[jbarker52]

The muffler and supercharger kit was installed by Vision Function around April of 2010. I do not know what is inside of the muffler, surely it has not deteriorated so soon. I will check with them and see what material they used. I really appreciate the tips. I guess a good pipe shop will be needed for a custom 3" directional tip. Thanks again

[MARKP]

Check the rules but I'm pretty sure an adjustable tip to direct the sound away from the sound meter is specifically not allowed, if that's where you were headed with that.

The Miata has a turndown on it but it doesn't move and the biggest reason it is there is because the heat from the exhaust is hard on the wiring harness if it doesn't have the turndown on it. It is actually quieter without it.

[Wheelman_13]

Check the rules but I'm pretty sure an adjustable tip to direct the sound away from the sound meter is specifically not allowed, if that's where you were headed with that.

The Miata has a turndown on it but it doesn't move and the biggest reason it is there is because the heat from the exhaust is hard on the wiring harness if it doesn't have the turndown on it. It is actually quieter without it.

There is some rule about directing the exhaust away from the meter, but if all he did was change it to where it's exiting towards the rear of the car vs. out the side, that's not really against the spirit of that rule. As long as it's not something that can be adjusted to be event specific to "beat" sound, I can't see a problem.

[MARKP]

Check the rules but I'm pretty sure an adjustable tip to direct the sound away from the sound meter is specifically not allowed, if that's where you were headed with that.

The Miata has a turndown on it but it doesn't move and the biggest reason it is there is because the heat from the exhaust is hard on the wiring harness if it doesn't have the turndown on it. It is actually quieter without it.

There is some rule about directing the exhaust away from the meter, but if all he did was change it to where it's exiting towards the rear of the car vs. out the side, that's not really against the spirit of that rule. As long as it's not something that can be adjusted to be event specific to "beat" sound, I can't see a problem.

Exactly.

[GaryM]

“Directing the exhaust away from the sound meter can be considered unsportsmanlike conduct and may be
referred to the Chief Steward for action under 1.3.2.L."

It's best to use something like a supertrap that you can add on if needed.

[jbarker52]

Thanks Gary for the tip about a super Trapp. I had not heard of it before, just scanned their web site, it looks promising. I can not tell you guys how much a downer it was for my son and my self. He had not got to drive in a auto x for over 2 yrs, drove 400 miles and only got to do 2 runs and they did not count. It is totally on myself and my car. Thanks again to every one.

[integra55]

ok didn't know that about the moveable tip... the SM racers that do it (this is W2W not a-x) know the tracks and where sound is usually set up and any changes are done before they get to the track.... exhaust always looks as though it's routed in that days direction as a normal setup...

[MARKP]

ok didn't know that about the moveable tip... the SM racers that do it (this is W2W not a-x) know the tracks and where sound is usually set up and any changes are done before they get to the track.... exhaust always looks as though it's routed in that days direction as a normal setup...

Yep, common with the road racers. You should know everything is easier when it comes to road racing.

[integra55]

autocross.... if it were easier it'd be called road racing

[John Brown]

after some thought away from the site and the event ...
I really think that the Lotus has had the packing burn out of whatever muffler is on the car. If in fact nothing has been changed on the car,this is really the only logical conclusion. We use Costal Fabricator mufflers on our RR cars and we have to pack them once a year.