Does the club have a decibel meter?

[SmokingTires]

I am wondering because I plan to open my exhaust up right after the cat for autocrossing. However after reading through the SCCA rule book (which our Met Counsil rules mostly follow, and I will be using as far for Nationals and Regional events), it says that exhaust levels have to be within reason, as determined by those running the event. So I just want to make sure my exhaust meets a decent level, otherwise I will need to fab something to quiet it down.

Thanks,
-Mike

[AlexL]

I am wondering because I plan to open my exhaust up right after the cat for autocrossing. However after reading through the SCCA rule book (which our Met Counsil rules mostly follow, and I will be using as far for Nationals and Regional events), it says that exhaust levels have to be within reason, as determined by those running the event. So I just want to make sure my exhaust meets a decent level, otherwise I will need to fab something to quiet it down.

Thanks,
-Mike
The SCCA rule is so open that as long as you're quieter than any of the mod cars at an SCCA event, you shouldn't have a problem. The met council rule about exhaust sucks, and I hope we can get it changed for next year at the next rules meeting. It requires all cars to have a street legal exhaust (what qualifies as a street legal exhaust on a Formula Ford?), but does allow for non-street legal exhausts on non-stock cars with approval from the EM.

Despite that, I plan on running a straight-through resonator/muffler after the cat with a turndown just before the rear suspension eventually. Soon to be a member of the "More Decibels Than Rear Wheel Horsepower" club.

EDIT:
And to answer your question, no, but I hear you can get them pretty cheaply from Radio Shack.

[Chin]

I have one (used for home audio tuning).... I am usually difficult to corner more than about 30 min in advance, but if you would like, we could try to hook up to make a measurement.

Christian Banks
#202 DSP
'00 Impreza 2.5RS

[tech b]

i fear my car may be too much for some. it's obnoxious at idle, and i have 3 mufflers on it....

[EWAustin]

what kind of car is it?

[stoooo]

what kind of car is it?
I'm guessing an RX-7...
Previous Thread (http://forum.mnautox.com/forums/showpost.php?p=46485&postcount=125)

Stuart.

[EWAustin]

that'd make sense. Wankels are generally loud, especially without a turbo.

[SmokingTires]

The SCCA rule is so open that as long as you're quieter than any of the mod cars at an SCCA event, you shouldn't have a problem. The met council rule about exhaust sucks, and I hope we can get it changed for next year at the next rules meeting. It requires all cars to have a street legal exhaust (what qualifies as a street legal exhaust on a Formula Ford?), but does allow for non-street legal exhausts on non-stock cars with approval from the EM.



Street legal in Minnesota means you don't even need a cat. ;) So you could run whatever you want. And as far as I know, MN doesn't have any sound limitations either.

After watching the video from this past weekend,, I can barely hear my car until it is past the camera and in high RPM (Chris was filming), so I can't imagine being open after the cat. would be that loud. But we'll see :D


Thanks for the offer Christian, I'll probably just hit a Radio Shack near my house.

-Mike

[89yotarollagts]

id love to hear another 4ag scream lol keep in mind the 4ag likes to rasp im having huge issues & spending way to much on my exhaust to fix this, just installed a magnaflow and its rasps 5 times more than my 4" folgers can. Goodluck ! i feel my car is rediculously loud, can only imagine what yours will sound like with the motor in the back ; )

[SmokingTires]

^
A large muffler will add a lot to the size of the sound. The rest of it will still be the stock 2" system, so it won't have too much room to expand. I'm not really worried about how nice it sounds, the main goal is for the weight savings :)

-Mike

[phile]

that'd make sense. Wankels are generally loud, especially without a turbo.
A ported normally-aspirated RX7 with no mufflers or converters can sterilize frogs.

I have been a grid marshal for Trans-Am, Formula 5000 and Can-Am cars. I have stood among the entire field of McLarens, Lolas and the like as they rolled to the flying lap. This was in the days when there were no no limits on the Can-Am and aluminum big-blocks abounded. I thought I knew about loud cars.

Nothing prepared me for the sound of the SINGLE RX7 ice racer of Steve (mumble, his dad owned the BMW dealer, it's on the tip of my tongue, I want to say it is "Walker" and the dad was Archie Walker. but another oldtimer needs to confirm). I was on the snowbank when he went by and my whole being just about short-circuited. I felt like a sonic boom had hit me in the chest. When the RX7 was on the other side of the lake, it drowned out cars right next to me.

It's not just that it was loud, it was also piercingly obnoxious. When he showed up at an icekhana in North Saint Paul, we got complaints from miles away.

If anyone showed up at an autocross with a fully-open NA RX7, We'd have to send him packing. We just can't have that kind of noise at any autocross site if we want this sport to survive.

As EWAustin says, a good way to quiet them down is use the muffler with the moving parts (turbo-supercharger).

[EWAustin]

I've only heard near-open 4AGE exhausts on AE86 Corollas. They're pretty loud (not rotory loud), and I'd think with the MR2 having even less exhaust length would be even louder. I've heard that some people, who take weight savings seriously (and don't have to have a cat) will bolt a supertrapp straight on to the exhaust pipe when it's still pointed straight back and run that right out the back end of the car. I haven't heard or seen this, but I'd imagine it would be pretty loud.

[89yotarollagts]

lol easy for you to say haha my broke college bum wont see any of that for awhile

~Smokingtires~ lol id be worried, if i wasnt so embarrased with my magnaflow id go to an event with it and have you hear it lol what are you planning on using for a muffler ?

[EWAustin]

Don't worry, I'm a broke college bum too. (just not taking any courses over the summer while I work full time to try to save up some cashish)

[AlexL]

Street legal in Minnesota means you don't even need a cat. ;) So you could run whatever you want. And as far as I know, MN doesn't have any sound limitations either.
Way wrong. Just because we don't have any emissions testing doesn't mean it's legal to go without a cat. There are noise regulations too, but they're vague and subjective.

[washburn]

Mike, if you want ot hear your car better in the video, remember my Neon video's? I clipped a remote microphone to the liscence plate frame near the exhaust. Made for some great vroom-vrooom sounds and you couldn't hear my comments while driving like "$*&$#%^#&" , and "*$&*#%#", and that time that I said "$*$&#% - *&^%%$$".

[SmokingTires]

Mike, if you want ot hear your car better in the video, remember my Neon video's? I clipped a remote microphone to the liscence plate frame near the exhaust. Made for some great vroom-vrooom sounds and you couldn't hear my comments while driving like "$*&$#%^#&" , and "*$&*#%#", and that time that I said "$*$&#% - *&^%%$$".


I want to hear it from external video (other people filming) to make sure I am getting on the gas at the right time. But mostly it's just for the weight savings. That's my main goal.

Alex, So you need a cat, but it doesn't need to serve it's purpose? Since there are no emissions, there's no way to inforce any standards. You could have it gutted and no one could check. Oh well. My car will still be stock class legal at least :)

-Mike

[the tick]

So you need a cat, but it doesn't need to serve it's purpose? Since there are no emissions, there's no way to inforce any standards. You could have it gutted and no one could check. Oh well. My car will still be stock class legal at least :)

-Mike

In stock and ST classes you need to run a stock or stock equivalent (i.e. no high flow and no modified) cat, after that the exhaust is open to interpretation (see Alex's post about EM being the judge on what is too loud)

[AlexL]

Alex, So you need a cat, but it doesn't need to serve it's purpose? Since there are no emissions, there's no way to inforce any standards. You could have it gutted and no one could check. Oh well. My car will still be stock class legal at least :)
If a cop pulls you over and suspects that your car is not emissions compliant, I believe you can still be ordered to provide proof of compliance. EPA emissions regulations are federal regulations. They apply regardless of state laws, or a lack thereof.

As for noise limits:
http://www.pca.state.mn.us/programs/pubs/noise.pdf

[jdlhonda]

Noise rules around here are just plain stupid and completely subjective. Cop once pulled my bro over because he could hear it from like 50 feet away with his window rolled down. It was so stupid and very subject to profiling of kids with tuner exhausts.

[Chin]

My understanding is that cats are required under federal law....MN law (or lack of, in this case) does not supercede that.

Christian Banks
#202 DSP
'00 Impreza 2.5RS