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Decibel rating


Eggy44
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Quick question, maybe someone could help me out with this.

 

Is the 92 dB reading at 50 feet being read at full throttle down the straight or at a certain RPM or how is it measured?

 

Maybe I'm just being dense 

Thanks ladies and gents

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  • Technical Advisory Committee

Most tracks have a mic positioned somewhere along the track.  Records as cars go by.  Or organizers dictate where mic goes.  Won't be in same spot relative to throttle use, rpm, side of car, near things that bounce sound around, etc at every track.

 

If you are concerned with sound level, increase the muffling ability or get the exhaust aimed the right way for where mic is located. 

 

If you are concerned and don't want to change car, find out where the mic is and make sure you are off/part throttle when near it.  And then be ready to mod the exhaust after corner workers/competitors call your car in for being loud.

Edited by NigelStu
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1 hour ago, Eggy44 said:

Quick question, maybe someone could help me out with this.

 

Is the 92 dB reading at 50 feet being read at full throttle down the straight or at a certain RPM or how is it measured?

 

Maybe I'm just being dense 

Thanks ladies and gents

If you aren’t racing at Laguna, do not worry about this rule. 

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5 hours ago, enginerd said:

If you aren’t racing at Laguna, do not worry about this rule. 

I normally agree with you on subjects....  not this one.

 

Loud cars are bad for the series.

 

They are annoying to literally everybody.  They lead to driver fatigue for the person in the car.  They help to get tracks closed.  They typically don't make any more measurable power.

 

Just say no to loud exhaust!

 

For the record we have run a rotary at lime rock with our quiet exhaust.  Didn't seem to hurt horsepower (2 x wins).

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I agree that loud cars are no good. We had a side exhaust with a single straight flow through muffler. You couldn't hear yourself think in that thing, let alone understand anything that was said on the radios. Another muffler and flowing out the back made a world of difference. 

 

But as per the 92db rule, don't stress about it, unless your car is completely ridiculous you won't have an issue. 

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8 hours ago, Eggy44 said:

Quick question, maybe someone could help me out with this.

 

Is the 92 dB reading at 50 feet being read at full throttle down the straight or at a certain RPM or how is it measured?

 

Maybe I'm just being dense 

Thanks ladies and gents

easy enough t control noise just ban all Miata's 

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2 hours ago, UglyBoost91 said:

This, haha. I don't understand the physics behind such a small amount of fuel and air making so much noise 😉

It's the abrupt opening of the exhaust port with no valve in the way to help attenuate the sound that produces the extremely brittle rotary exhaust note.

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39 minutes ago, mender said:

It's the abrupt opening of the exhaust port with no valve in the way to help attenuate the sound that produces the extremely brittle rotary exhaust note.

 

Even with my helmet on, its like a nickleback song at max volume....makes your ears bleed and you feel the need to evacuate your stomach after hearing it.  Unless its a 787B...that one sounds like angels singing led zeppelin 

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43 minutes ago, mender said:

It's the abrupt opening of the exhaust port with no valve in the way to help attenuate the sound that produces the extremely brittle rotary  Super amazing swam of angry bees exhaust note.

 

Fixed that for you :P

 

 

Yes some do sound like **** but not all

Edited by Wittenauer Racing
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23 minutes ago, Gearhead_42 said:

I can guarantee you that my racecar is actually quieter than either of my streetcars...   The factory "muffler" @ the manifold outlet has a lot to do with that though :lol:

our car was way to quiet... We are going to use a better (louder) muffler when we transfer everything to the new shell.  At NJMP standing on the viewing platform you could barley hear the V8 pushing 6k down the straight...of course every 4 banger you could hear from start to finish. 

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Y'all that are cracking on the rx7s...those people that run rx7 that are loud are idiots..we have 8 wins between lemons and chump...  5 chump wins...

 

Our rx7s are some of the quietest cars on track.   

 

Tune it with good sound attenuation and make power.  Big, open exhaust on rx7 is not actually best for hp.

 

Yell and scream at those with loud rx7.  They are doing it wrong. Just like loud and obscene bmw, 4age, miata, etc...  loud does not equal fast.

 

When was the last time a loud car won?

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11 hours ago, UglyBoost91 said:

This, haha. I don't understand the physics behind such a small amount of fuel and air making so much noise 😉

You obviously don't understand rotaries if you think They take a small amount of fuel...  think 7.5 to 8 gph....  for an engine making 150 hp....

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2 hours ago, wvumtnbkr said:

Rotarys are the most efficient engine on earth at taking gasoline and making noise without the dangerous by product of torque!🤣

I'm not sure about that, the Subaru is still WAY louder than the RX7 and can't get out of its own way until it gets into boost.

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15 hours ago, wvumtnbkr said:

You obviously don't understand rotaries if you think They take a small amount of fuel...  think 7.5 to 8 gph....  for an engine making 150 hp....

Haha true, I forgot they sucked down fuel like a pig. Truth be told I'm a piston guy through and through, I haven't even seen a rotary under a hood in 15 years nor do I have a desire too. 😎

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