I ran some sound tests today

by "Flynorcal: pilot, offshore sailor, car racer and panty thief" (flynorcal)
Published 06/24/2017 at 21:33

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Were they scientific? They were!

I mentioned before here about Laguna Seca having a sound meter. If you’re louder than 92db (measured at 50' away on the right at turn 5) and can’t keep your car under that you get black flagged and sent home. So what do you do if you have a loud car?

The corvette is 96db when I start it if you’re measuring from right outside the car.

So I have slip on muffler tips to redirect the sound away from the meter.

I ran three tests. I had a very patient woman measure sound from 50' on a closed runway and went past as redline a few times.

I was good with nothing at all, reading 91db. However turn 5 is also a hill so that bit of load might erase that margin.

With the tips I got down to 87.9db. That works!

Then I went the extra mile and stuffed in some fireproof muffler packing used for motorcycles and put some mesh in to hold it and the bolt that holds the tips on held that too.

81db! 81! Bam!

Replies (6)

"Flynorcal: pilot, offshore sailor, car racer and panty thief" (flynorcal)
06/24/2017 at 21:43, STARS: 1

Oh and the car didn’t seem to mind the packing any but it did not care for some of my driving. Whining bastard.

"Tristan" (casselts)
06/24/2017 at 21:49, STARS: 1

Brilliant! But, goodness gracious-put down a towel or a blanket or something between the paint and the tool boxes! I sure do like that C4 of yours.

"Flynorcal: pilot, offshore sailor, car racer and panty thief" (flynorcal)
06/24/2017 at 22:02, STARS: 1

Thanks! And will do.

"JGrabowMSt" (jgrabowmst)
06/24/2017 at 23:08, STARS: 0

No you have to dyno test and see if you have a loss in power.

Mathias had a muffler for his old Saabaru wagon, I couldn’t even imagine how much horsepower he lost when that was in...

"Flynorcal: pilot, offshore sailor, car racer and panty thief" (flynorcal)
06/24/2017 at 23:18, STARS: 2

I’m sure I lost some HP as taking it all back out I unpacked the muffler just by starting the car without the retaining bolt in the way. It’s blocking a lot of air.

However, two points:

- Not being booted off the track is worth a few HP.

- It started life with a meager 300hp due to gas availability in 1992 and was built to handle to keep it sporty.

At Sonoma they offer a deal sometimes — three dyno pulls for $75 I think it is. They announce it sometimes on the PA. I’m of the mindset to try seeing what the three setups do. Mostly I’d be curious what just the redirecting tips do as who knows versus the obvious with the packing in the way.

"BiTurbo228 - Dr Frankenstein of Spitfires" (biturbo228)
06/25/2017 at 05:53, STARS: 1

Haha ;) I like your original idea (minus the extra padding). Less make it quieter, more point that noise away from the measurement. Nice and subtly defiant of a frankly bloody stupid noise limit ;)