Eggy44 Posted June 15, 2018 Report Share Posted June 15, 2018 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 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee NigelStu Posted June 15, 2018 Technical Advisory Committee Report Share Posted June 15, 2018 (edited) 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 June 15, 2018 by NigelStu Quote Link to comment Share on other sites More sharing options...
enginerd Posted June 15, 2018 Report Share Posted June 15, 2018 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. Quote Link to comment Share on other sites More sharing options...
Racer7x Posted June 15, 2018 Report Share Posted June 15, 2018 4 hours ago, enginerd said: If you aren’t racing at Laguna, do not worry about this rule. AMP has a problem with sound, so you need to worry about it there also. Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted June 15, 2018 Report Share Posted June 15, 2018 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). 4 1 Quote Link to comment Share on other sites More sharing options...
Black Magic Posted June 15, 2018 Report Share Posted June 15, 2018 I don't think there is a piston engine in this series that couldn't pass sound with a simple glass pack muffler pointed the right way. Work on it, but it doesn't take much..... Quote Link to comment Share on other sites More sharing options...
thewheelerZ Posted June 15, 2018 Report Share Posted June 15, 2018 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. Quote Link to comment Share on other sites More sharing options...
TiredBirds Posted June 15, 2018 Report Share Posted June 15, 2018 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 1 Quote Link to comment Share on other sites More sharing options...
Eman911 Posted June 15, 2018 Report Share Posted June 15, 2018 And rotaries! 1 1 Quote Link to comment Share on other sites More sharing options...
UglyBoost91 Posted June 15, 2018 Report Share Posted June 15, 2018 17 minutes ago, Eman911 said: And rotaries! This, haha. I don't understand the physics behind such a small amount of fuel and air making so much noise Quote Link to comment Share on other sites More sharing options...
mender Posted June 15, 2018 Report Share Posted June 15, 2018 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. 1 Quote Link to comment Share on other sites More sharing options...
Jab31169 Posted June 15, 2018 Report Share Posted June 15, 2018 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 4 Quote Link to comment Share on other sites More sharing options...
Wittenauer Racing Posted June 15, 2018 Report Share Posted June 15, 2018 (edited) 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 Yes some do sound like **** but not all Edited June 15, 2018 by Wittenauer Racing Quote Link to comment Share on other sites More sharing options...
mender Posted June 15, 2018 Report Share Posted June 15, 2018 12 minutes ago, Wittenauer Racing said: Fixed that for you Yes some do sound like **** but not all I've had five RX7s so far ... Quote Link to comment Share on other sites More sharing options...
Gearhead_42 Posted June 15, 2018 Report Share Posted June 15, 2018 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 Quote Link to comment Share on other sites More sharing options...
TiredBirds Posted June 15, 2018 Report Share Posted June 15, 2018 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 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. Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted June 16, 2018 Report Share Posted June 16, 2018 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? Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted June 16, 2018 Report Share Posted June 16, 2018 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.... Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted June 16, 2018 Report Share Posted June 16, 2018 Rotarys are the most efficient engine on earth at taking gasoline and making noise without the dangerous by product of torque! 1 3 Quote Link to comment Share on other sites More sharing options...
bbaker480 Posted June 16, 2018 Report Share Posted June 16, 2018 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. Quote Link to comment Share on other sites More sharing options...
UglyBoost91 Posted June 16, 2018 Report Share Posted June 16, 2018 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. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.