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42DD downpipe noise level - anyone have numbers?

Pseudo Nim

Ready to race!
So my track requires <92dB. Anyone know what noise level the 42DD catless, downpipe produces with the stock catback? I doubt it's over 92, but then again, who knows.
 

XGC75

Go Kart Champion
92 is massive. Street levels tend to be around 85 - 88, and since decibels are logarithmic each additional decibel is a louder step up than the last. I don't think a straight pipe would see 92 dB.

butchered by autocorrect
 

Pseudo Nim

Ready to race!
I wonder if (and here I admit to utter ignorance) noise level is comparable across similar size engines - since there are a lot more GTIs, maybe I should look for dB levels of a straight pipe GTI and figure I'll be below that?
 

greasyginzo

Go Kart Champion
I really doubt they are going to take a db meter to your car. If they do meter cars at tech its most likely american V8s with loud exhaust or one of those crazy turbo Honda's with dump tubes sticking out of the hood
 

Pseudo Nim

Ready to race!
I really doubt they are going to take a db meter to your car. If they do meter cars at tech its most likely american V8s with loud exhaust or one of those crazy turbo Honda's with dump tubes sticking out of the hood

Sadly, it's a meter station that clocks every passing car. They're quite strict on noise :( But I've looked around some more and I think I should be fine. My car is loud, but more bass note loud, so at 25' or whatever they measure, it's very unlikely to redline the meter, unlike a high-revving M3 or something like that.
 

greasyginzo

Go Kart Champion
Sadly, it's a meter station that clocks every passing car. They're quite strict on noise :( But I've looked around some more and I think I should be fine. My car is loud, but more bass note loud, so at 25' or whatever they measure, it's very unlikely to redline the meter, unlike a high-revving M3 or something like that.

Where is the metering station? Is it at some point on the track or is it something at tech? I highly doubt you would be anywhere close to their limit. You could always but they resonated section from 42DD for the downpipe and quiet it down a little if necessary but I think you will be fine.
 

Pseudo Nim

Ready to race!
Where is the metering station? Is it at some point on the track or is it something at tech? I highly doubt you would be anywhere close to their limit. You could always but they resonated section from 42DD for the downpipe and quiet it down a little if necessary but I think you will be fine.

It's on a straightaway :) I do agree though. Really think I'm worrying for nothing. We'll know in 2 weeks :)
 

Pseudo Nim

Ready to race!
Update to my own question


- 86 dB standing WOT (fuel cutoff just below 4,000 rpm though, so very quiet)
- 96 dB at load once passed 4,000 rpm (this is when it gets exponentially loud) at approx 30ft. Holy shit it's loud.

So just remember that if the track does a standing soundcheck, you will be fine - but if it's under full acceleration, then be careful.
 

XGC75

Go Kart Champion
Update to my own question


- 86 dB standing WOT (fuel cutoff just below 4,000 rpm though, so very quiet)
- 96 dB at load once passed 4,000 rpm (this is when it gets exponentially loud) at approx 30ft. Holy shit it's loud.

So just remember that if the track does a standing soundcheck, you will be fine - but if it's under full acceleration, then be careful.

96 :eek:

I've heard people saying this setup "isn't bad". For the record, that's insane. Wtf

butchered by autocorrect
 

Pseudo Nim

Ready to race!
Update: something really bizarre happened. I had the DP on for about a month or so and no noise changes (which is why I was concerned upthread). I took it out on the track last weekend, and it still behaved similarly - quiet up to about 4,000 rpm and tremendously loud after.

But.. about halfway through the day (although I didn't quite notice when) it ....... stopped doing that.

And now, it's been almost a week since the track event, and I have no more nuclear blast at 4,000 rpm. The sound modulation is perfectly linear: sound increases in volume right up to the redline, but there is no more spike at 4,000. It's also overall quieter.

Wtf happened? It's not like the the dp needed a breakin - I had it on for what, a month, and probably put 1k miles on it in varying intensity?

I am very confused.
 

lamb110

Go Kart Champion
Did the valve in the catback break? That's why it gets loud at 4k.
 
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