....if all every racer ever does is point the noise away from the guy measuring??? you AREN'T reducing the noise level (i'm sure you all realize this). what you ARE doing is jeapordizing the track's ability to operate. most track sound level mandates are pushed by the surrounding neighbors. **** them off enough and they'll find a way to stop the noise. permanently.

who wants to be the guy fingered for having a track shut down because all he did was point his exhaust away from the meter instead of actually making it quieter? not me, but i'll be sure to jump all over jackass that does it. this goes for autocrossers too. the NER's only two autocross sites both have sound limits. we almost lost the better of the two sites just last year due to noise.

nate - stepping off his soapbox

 

Actually, sound guy is usually between the track and the neighbors ... and pointing away from him can often bite you in the nads when sound bounces off the wall anyway. Deaden the bell that is the under part of your car or keep it quieter in general is my way of looking at it.

 

and while I wholeheartedly agree, let me ask you this:

I am building a car as we all know. My exhaust is header, muffler, down turn. I have NO idea how loud it is going to be. Even after i start it, I have no idea how it will register on a particular track meter.

So what am I supposed to do?

I can bring a bunch of extra mufflers with me to the track and hope that one of them will be quiet enough. I can buy and bring a welder to the track to try and have more than one muffler and hope it will be quiet enough.

Neither solution is very practical. So I plan on getting to the track, and if I get meatballed, I will turn the down spout away from the meter and get a different muffler for the next time I get to the track. I'll keep doing that until the car is quiet enough.

I am open to other reasonable suggestions.

 

Sound control has its obvious point of keeping the neighbors hopefully off the **** of the track owners. While yes, some point the exhaust away from sound control still there is a DB limit and even doing that can not circumvent too significantly the DB limit. Noise nuisance is a serious threat to any track if not policed. I live six miles away from Barber Motorsport Park and some weekend I can hear the cars or bikes on track but it is pretty unobtrusive at my distance. Put an old IMSA GT lite rotary GTP on track with no muffler and you are talking some serious obnoxious noise. I remember when HSR ran the first year there and I am sure they got tons of complaints on those cars.

Barry H.

 

I live about 8-10 miles from a country dirt track and I can hear the V8s barely from my house depending on the atmospheric contirions.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SJR &raquo;</TD></TR><TR><TD CLASS="quote">
I am building a car as we all know. My exhaust is header, muffler, down turn. I have NO idea how loud it is going to be. Even after i start it, I have no idea how it will register on a particular track meter.

So what am I supposed to do?
:</TD></TR></TABLE>

You should be fine for the 102 limits that most tracks have. Unless the pipe diameter is small (2 inch or so is raspy and louder), then all of my experience with a CRX and 2.5 pipe with a race muffler will put you in the mid-to upper 90s range. If you get nailed for sound at the first event or two then just run to Pep Boys and get a Cherry Bomb or other straight through muffler, some cheap clamps and a hacksaw to temporarily knock the sound down acceptably and then really fix it later. That car is pretty well proven to be well under most track limits unless it is really low like Waterford Hills (max is in the 80s) were you will need to make a more compete system. Bigger tubing is deeper with less high end rasp sound so any decent but cheap race muffler should give you no worries. The Cherry Bomb is cheap and a temporary fix, most agree that it is a power sucker but it will let you run the rest of the weekend.

 

I just put together a new exhaust system that i'm hoping will be enough for keeping sound levels down. I have a B18C with 4-1 header, 2.5" collector and piping running through 2 magnaflow 4" round body mufflers one 14" long which is upstream and one 22" long downstream. Has anyone tried a setup similar to this and had a decibel reading?





Modified by B18CJDM at 8:37 PM 12/22/2004

 

Wow, its amazing to read this thread on the same day that I also read ~"Its pretty well known that the honda engines run best with no back-pressure"~ (see Catch22's comments on the Mugen Muffler in Tyson's thread). Now "run best" might be a more specific statement to road-race than autocross, but still, when Catch22 says something, I listen.

Our San Antonio club recently lost its autox lot because of noise complaints (the parking lot of the Alamodome, where there are also high school marching band contests!). I'm building a daily driver/ autox 91 CRX, and I'm just mortified of getting an exhaust that becomes a nosie problem. (Hey, I dont like to listen to other peoples noise while I'm in my home). But on the other hand, I do want to get the most out of what I've got.

So then I just read that a 2.5" is quieter than a 2" exhaust???? If what Catch22 says is true, then that is really good news. Can anyone really confirm this?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18CJDM &raquo;</TD></TR><TR><TD CLASS="quote"> I have a B18C with 4-1 header, 2.5" collector and piping running through 2 magnaflow 4" round body mufflers one 14" long which is upstream and one 22" long downstream. Has anyone tried a setup similar to this and had a decibel reading?
</TD></TR></TABLE>

This is exactly what I am running. Built by Raceworks. I have not ran it yet, but they run the same setup on their H1 car which has not hit more then 100db.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fireant &raquo;</TD></TR><TR><TD CLASS="quote">So then I just read that a 2.5" is quieter than a 2" exhaust???? </TD></TR></TABLE>

In many ways it makes sense. I know that just judging by "ear," I'd think that V8s are a LOT louder than any four banger (especially a little 1.6L CRX Si) but if you look at sound readings for two cars that seemingly split the ear just as loud, the 4 bangers always seem (to me) to have higher readings (and seem to be more shrill too). I think a lot of what goes down w/ sound control has to do w/ tone as much as volume.

- attempting to draw a conclusion that 2.5" would have less high tone than 2.0" dia.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fireant &raquo;</TD></TR><TR><TD CLASS="quote">Wow, its amazing to read this thread on the same day that I also read ~"Its pretty well known that the honda engines run best with no back-pressure"~ (see Catch22's comments on the Mugen Muffler in Tyson's thread). Now "run best" might be a more specific statement to road-race than autocross.
</TD></TR></TABLE>

You might be surprised to hear that my car registered exactly the same dbs in the session that the exhaust fell off than it did with the exhaust.
It was WAY louder *inside* the car, and my right heel got kind of hot, but outside the car friends, crew, and the sound meter couldn't tell the difference.
IIRC it was right at 96dbs with and without exhaust. The car has never been over 100 (98 on a really cold crisp day at VIR was the top so far)

Collector and exhaust are 2.5". Its a D15B1 thats typically near the rev limiter when it passes sound control.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fireant &raquo;</TD></TR><TR><TD CLASS="quote"> when Catch22 says something, I listen.
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Be careful. I make most of this **** up.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phat-S &raquo;</TD></TR><TR><TD CLASS="quote">Actually, sound guy is usually between the track and the neighbors.</TD></TR></TABLE>

Give that man a seeegar.

 

I point out a specific example, Laguna Seca....homeowners moved in AFTER the track was built and operated and even during race days, they are allowed to run high db's (103 and 107) within specific hours. That means testing is f'd if you're looking for hp and tuning.

 

i'm not replying to any specific person, nor am i attacking anyone.

imo, if you run at a track that has a sound restriction and you are concerned that you might not pass sound you should be building a quieter exhaust to begin with. at the very least you should bring an alternative exhaust that is well on the safe side as far as noise is concerned.

loud does not necessarily mean low back pressure and big power. obviously a better flowing exhaust will be louder then OEM, but it doesn't need to be ear splitting loud. there is also good evidence that a quieter race car allows the driver to focus better and absorb more information about what is going on with the rest of the car, particularly the tires. not 100% fool proof, but the theory makes sense.

sound frequency does play a role in this, just like someone else said. some cars that aren't necessarily loud can easily be accused of being more abnoxious entirely because of the tone. a track that doesn't allow turn downs pointed away from the sound meter would have an easier time defending abnoxious sounding cars since they could easily prove they are well under the agreed sound limitation. turn downs pointed away from the meter could be easily seen as "thumbing your nose" at the sound limit and disrespecting the town that the track resides in.

i'm addressing the racers hear, but i really feel that this should be a mandate from the tracks governing body. if everyone is forced to be quiet and not just point their exhaust a different direction then everyone will be faced with the same hardship. true, the guys with more money won't be affected as much, but thats life.

i'm probably overreacting but this is one of those things that i feel it is better to be paranoid and safe then not. i can live with a quiet race car (oh but it sounds so nice uncorked!) but its just a planter if i can't actually race it.

nate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by solo-x &raquo;</TD></TR><TR><TD CLASS="quote">i'm not replying to any specific person, nor am i attacking anyone.

imo, if you run at a track that has a sound restriction and you are concerned that you might not pass sound you should be building a quieter exhaust to begin with. at the very least you should bring an alternative exhaust that is well on the safe side as far as noise is concerned.

loud does not necessarily mean low back pressure and big power. obviously a better flowing exhaust will be louder then OEM, but it doesn't need to be ear splitting loud. there is also good evidence that a quieter race car allows the driver to focus better and absorb more information about what is going on with the rest of the car, particularly the tires. not 100% fool proof, but the theory makes sense.

sound frequency does play a role in this, just like someone else said. some cars that aren't necessarily loud can easily be accused of being more abnoxious entirely because of the tone. a track that doesn't allow turn downs pointed away from the sound meter would have an easier time defending abnoxious sounding cars since they could easily prove they are well under the agreed sound limitation. turn downs pointed away from the meter could be easily seen as "thumbing your nose" at the sound limit and disrespecting the town that the track resides in.

i'm addressing the racers hear, but i really feel that this should be a mandate from the tracks governing body. if everyone is forced to be quiet and not just point their exhaust a different direction then everyone will be faced with the same hardship. true, the guys with more money won't be affected as much, but thats life.

i'm probably overreacting but this is one of those things that i feel it is better to be paranoid and safe then not. i can live with a quiet race car (oh but it sounds so nice uncorked!) but its just a planter if i can't actually race it.

nate</TD></TR></TABLE>

you are 100% right, rules are rules and should be followed but people get pretty passionate about the db regulations at laguna seca, racers and neighbors. Stock cars, yes, 100% stock cars have hit higher than 91db, 92db, and 93db there. The people that live at the track moved in after the track was built. Their lawn mowers are louder than some cars at laguna seca and it's (IMO) ridiculous to have such strict conditions at a historic race track. The sound metering costs extra to rent the track and results are a more expensive track day. Still, it's a blast to drive on that track and worth the troubles of clamping on a POS supertrapp to meet sound regulations. You'd laugh to see what some of the of the Porsche guys do with redirecting tips and mufflers to pass sound there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPiFF &raquo;</TD></TR><TR><TD CLASS="quote">This is exactly what I am running. Built by Raceworks. I have not ran it yet, but they run the same setup on their H1 car which has not hit more then 100db.</TD></TR></TABLE>


Actually, the car has hit 101-102, but that is only in particularly cold weather. Get used to the noise thing getting to be a bigger and bigger problem as time goes on. In most cases the track was there first, but it doesn't matter. The NIMBYs can afford to hire good lawyers, and a bunch of irate homeowners as a lot more clout with city hall than some out-of-state adrenaline jockeys.

It's going to get really fun when the EPA decides to put emissions standards on race cars.

 

Yeah Nate, OK.
But please read this again...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phat-S &raquo;</TD></TR><TR><TD CLASS="quote">Actually, sound guy is usually between the track and the neighbors</TD></TR></TABLE>

If your sound people know what they are doing, and are set up in the right spot, pointing your turndown away from Sound Control accomplishes the end you're looking for. It not only directs the sound away from SC, it also directs it away from the people who might be complaining.

I've never been to laguna, but I know that this is the case at every track at which I've run.
Now, if the track is SURROUNDED on all sides by housing (and frankly I've been to 10 race courses and have never seen that), that might be a different story.
Dunno, but here in the SE we are lucky enough that most all of our tracks are in the boonies. The only place where there is a neighborhood located *close* to the track is Roebling Road, and guess where Sound Control sets up???

 

To the pictured exhaust above- It should work quite well! I ran a similiar setup of 1 of those cans and I was @ 90db! so you hsould be way under!

 

I'll also add that many of the tracks have agreements with the towns/neighbors about how sound will be measured. These agreements are exacting in nature, as in, "sound will be measured from X distance at Y point where cars are traveling at Z throttle." If the track meets these requirements, the neighbors can't really complain.

So if a turn down meets the requirements, then use the turn down. Otherwise, if meeting the requirements isn't good enough, then you could go all the way to the extreme, saying all cars should be as quite as possible, cork those puppies up! And we'd all be racing silent electric cars.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fireant &raquo;</TD></TR><TR><TD CLASS="quote">Wow, its amazing to read this thread on the same day that I also read ~"Its pretty well known that the honda engines run best with no back-pressure"~ (see Catch22's comments on the Mugen Muffler in Tyson's thread). Now "run best" might be a more specific statement to road-race than autocross, but still, when Catch22 says something, I listen.</TD></TR></TABLE>

I think the reluctance to use adequate mufflers is blown out of proportion. Back pressure can increase using straight tubing, too. Just as there are pressure drop tables for different lengths and sizes of steel braided hose, there is also resistance added the longer exhaust system gets. Everyone assumes that mufflers will increase back pressure, and in most cases that's true. But increase BP compared to what? No tubing at all and exhaust falling straight out of the collector?

Take a good look thru an uninstalled Magnaflow (or similar type) race muffler. What you'll see is nothing. No baffles, no louvers, no diverters or traps. The inside of the muffler is a straight section of tubing that is perforated (think "drilled") with small holes that allow the sound waves to be absorbed and damped by the packing wrapped around the outside of the perforated tubing. The longer the muffler, the more sound wave absorption. Yes, the perforated tubing in the muffler flows worse than nothing at all. It also flows slightly worse that an equal length of straight exhaust tubing. But the difference in flow is minuscule compared to baffled or chambered muffler designs. As a point of reference, think of a "silencer" on a gun. The sound damping material is OUTSIDE the bore of the cylinder. There is still a straight bore thru which the bulllet can exit the gun barrel. And it will still hit whatever its aimed at.

Sound limits and good hearing are good things. I don't miss the loud race cars I heard growing up around Riverside and Ontario one bit. What I do miss is the tone, quality and pitch of the noise those cars made. But that is the price we must pay for better hearing, happy neighbors and great places to play with our junk.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Shmeek &raquo;</TD></TR><TR><TD CLASS="quote">I'll also add that many of the tracks have agreements with the towns/neighbors about how sound will be measured. These agreements are exacting in nature, as in, "sound will be measured from X distance at Y point where cars are traveling at Z throttle." If the track meets these requirements, the neighbors can't really complain.</TD></TR></TABLE>

Of course they can complain! The average subdivsion-denzien believies it's their God-given right to regulate what color curtains their neighbor has. What chance does a race track have? Have you seen how terrible the lawn looks at your local track?

All it requires a strong enough hangover when those race cars start up and the Snooty Grove Home Owners Association will be making petitions made to reduce the sound levels to 2DB on race weekends.


For the record, the most ridiculous sound regulations I've ever been subjected to was at the pro races at Portland in 2001. They actually had different sound limits by class. ALMS was 108, Trans-Am was 105, and World Challenge was 103. Something about birds not being able to hump if it was too loud was the excuse.

 

From what I understand about sound control (one of my friends does SC for the Alabama and many times the Atlanta region SCCA) the location of sound control has to be certified by the SC administrator of the division. What they are looking for is a place that has the least problems such as surrounding structures to bounce sound or cause an artificial increase in the DB level. They also have to find a place where you have to be WOT on the track(at least if you don't want to get passed by lifting). It is all usually a bit of a compromise but once that location is certified yep, that is where it is done from. The Alabama region just purchased about $2,000 worth of sound control equipment for its club racing program. Very accurate, high tech, and nice. Part of that is a hand held $250 portable weather station that measures every darn thing and I believe maybe even air density. All of that is taken is documented with the sound readings.

But then what is a decibel? This link has an explanation and some wave files showing comparison.
http://www.phys.unsw.edu.au/~jw/dB.html

I don't see sound control as a bad thing. As a corner worker at the 03 HSR at Barber Motorsports the I believe Tiga and Spice Camel GT lite GTP rotary prototypes ran there with no sound control. The cars were too freakin loud. Quite a few workers talked about how obnoxious the cars were. They would not be allowed to come back without muffler's now. I live about 6 miles away from the Barber track as the road goes (kind of winding) and I can on many weekends hear bikes or cars running on the track but it is more of a background noise type of sound. I know what it is but it does not disturb my "peace". Grand Am weekend for whatever reason I could hear the cars much louder on saturday and that should have been the touring series not the DTPs from what I could figure. When I sat outside (I didn't make it to the race this year for various reasons) on my porch it was starting to get somewhat intrusive but I am sympathetic (to a point) of such noise as a homeowner. Now if I lived three miles away from the track I could see where it could be borderline on the comfort zone. I love the sound of engines revving up but I don't think I would want to hear that at home at a loud volume constantly for 8 hours a day for two or three days. I will say if you move within a mile of a race track you have to expect to hear a good bit of noise.

Barry H.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Want2race &raquo;</TD></TR><TR><TD CLASS="quote">To the pictured exhaust above- It should work quite well! I ran a similiar setup of 1 of those cans and I was @ 90db! so you hsould be way under! </TD></TR></TABLE>

Good deal, thanks for your input. I was worried 1 wouldn't be enough so I decided to build it with 2.

 

it must be nice to have your track relatively secluded. one of our autocross sites is like that too. the other, neighbors on all sides. i suppose a case by case approach could be used, but like someone else said, the problem with noise restrictions is only going to get worse. one argument is that if we quiet things down voluntarily we might avoid having an impossibly strict level set for us by the town.

an outdoor kart track in the boston area went to great lengths to make sure the karts were quiet. the neighbors complained anyhow, but when sound measurements were taken it was discovered that the ambient noise around the track was louder then the noise the track was producing. obviously that is the best case scenario, but imo being able to prove that good faith measures were taken long before any complaints were made can go a long way in smoothing track, town and neighbor relations.

i will agree that most of the complaints are really stupid. san diego region has a sound restriction when they run at qualcomm stadium. there is a 4 or 5 lane major highway between the stadium and the residential places on one side, a mass transit rail system on another. the only other open side is a commercial zoned area with malls, shopping plaza's and what-not. unfortunately for us, the towns listen to their tax payers more then they listen to cone dodgers or fender bangers.

nate

ps. catalytic converters do a lot to reduce noise levels, with little to no power sacrifice. i run an OEM b-pipe, cat, dc 4-2-1 header and aem cai and i'm in the low 80dB range at WOT measured at 75ft.

 

Well, I got it all welded up, mounted and tested and I have to say it's quieter than I expected it to be. It isn't raspy at all, has a nice deep tone, and isn't as distracting as my worn out Hyper Medallion w/ test pipe. The only drawback it has is the vibration from inside the car which I had expected since it's stripped out, and exits just before the gas tank.







Modified by B18CJDM at 1:23 PM 12/24/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Raceworks &raquo;</TD></TR><TR><TD CLASS="quote">
For the record, the most ridiculous sound regulations I've ever been subjected to was at the pro races at Portland in 2001. They actually had different sound limits by class. ALMS was 108, Trans-Am was 105, and World Challenge was 103. Something about birds not being able to hump if it was too loud was the excuse.
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Track management had sound waivers for the weekend but only for short durations. 103db during a race weekend is what is normally accepted and the waivers were granted only for ALMS and Trans-Am. It does seem odd though, especially considering that the track is owned by the City of Portland.

Was it also rediculous that the WC teams knew many, many months in advance that they would have to meet these requirements yet a ton of the teams blew way over the limit and right up to the ALMS limit? Seems they didn't care to do their homework.

Halfway through the 25 hours of Thunderhill the allowable db level is reduced and stays put for the remainder of the event. We have one track in Canada that the max allowable is 95db. On nice cool morning, you can here the other groups from the hotel 2-3 miles away.

Personally I think 103db is sufficient to have fun racing and listening to racing. I do think that the neighborhoods will continue to put pressure on the noise racetracks develop and we will see sound limits drop even further.

I think it is our best interests to be good tenants at the tracks and the neighborhoods the tracks exist in/by/around. That means keeping our cars well under the max sound limits, not firing engines too early or too late, and not making testing runs on the access roads and out through the neighborhoods (jhill ).

Rick

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vapor &raquo;</TD></TR><TR><TD CLASS="quote">I point out a specific example, Laguna Seca....homeowners moved in AFTER the track was built and operated and even during race days, they are allowed to run high db's (103 and 107) within specific hours. That means testing is f'd if you're looking for hp and tuning. </TD></TR></TABLE>

GRRRRRRRRRRRR i hate people like this there FREAKING IDIOTS. Same thing happened with airports too, i think it was ontario (sp). Airport had been there forever, people moved in around it and started complaining about late night flights. HMMMMMMMMMMMMMMMMM lets see you move close to an airport that has had late night flights and your ok with now AFTER THE FACT that you live there your pissed about it. Same thing happened at Sacramento International airport, but offcourse the lawsuits were all turned down.

LS is the one that really ticks me off.

As far as with AutoX in parking lots and stuff, why don't they just inforce the rules? Some one goes over the DB limit pull them in next time they go out if its not fixed well they can't go out anymore. I know at Sears point they are pretty strict about it, and the only houses that are close are on the other side of the hill.


Turning the exhaust away, adding more mufflers, ect whatever can get you passed the sound check is perfectly fine. The only rule is you CAN'T go over that set DB do anything you can to get your self under it and your set.