Quiet the race car while in the garage... second muffler, glass pack, or something else?

Yes, I know the real answer to this is that I need to move. Work in progress on that front.

I bought a formula race powered by a motorcycle motor. You'd think that might be quieter given it's size but it is crazy loud parked in my garage in a subdivision. Over 90 decibel at idle. I'm trying to be a little nice to my neighbors until I move to a place where I have more land. Plus as much as I enjoy the sound of the race car, especially at 15,000 RPMs, there is no reason I need it to be that loud when I'm just working on it and testing something. Save my hearing loss for the track.

I don't want to do anything that isn't temporary and getting rid of CO gas is also an issue so I was going to buy Crushproof flex pipes to clamp onto the existing muffler to get rid of the gas. But the noise is my other issue. I'm wondering if I were to add an automotive muffler in my crushproof pipes, like a thrush hush or glass packs or something, if that would really help or if I should be concerned about additional back pressure, etc. I thought I read that was mostly a concern for two stroke motors, mine is not, but I'm not entirely sure if I should have to worry about it or not.

So aside from the easy answer of moving, which takes time, anyone have some ideas that might help?

A turbo is one of the best mufflers out there

A glasspack will add almost zero backpressure but it won't cut the noise down a whole lot either.

If this is just for temporary use while in your neighborhood, you should look into clamping on a supertrapp in place of the tip...or a soda can with some holes punched in it, that'll work too and it's cheap

What about a big cart-mounted truck muffler with some flex pipe? Think engine dyno setup.

Plenty of cheap mufflers at Summit Racing. I just picked up a decent one for like 20 bucks, shipped. Quieted my straight pipe down and made it sound much better overall.

Racingbeat universal mufflers are REALLY good.

Many auto shops in cold climates run a long piece of this through the garage door. Attaching some kind of muffler on the other side would probably be a good idea.

ncjay wrote: Many auto shops in cold climates run a long piece of this through the garage door. Attaching some kind of muffler on the other side would probably be a good idea.

Although this will help him from being overcome by exhaust fumes in a closed structure, channeling the current exhaust outdoors alone may exacerbate the noise issue with said neighbors? Now if you do this with added muffling device (s) then you may have accomplished what you want.

A lot of exhaust shops have a big dumpster full of factory take off piping and mufflers out back. A giant diesel muffler on a cart with some flex pipe leading to it should muffle your car down to about nothing. For moving testing you could make a temporary setup to mount a big car muffler above your rear deck. Think giant can with the flow changing direction and lots of absorption material inside.

I second the above about buying a universal from Summit or JEGs. I did that with my FF when I was running it in the garage. I used a section of flex pipe with a generic muffler. No pretty but effective.

bucket of water, done. run the pipe into the top, let it bubble. been working for boats for over a hundred years.

-J0N

Supertipp.

A chambered muffler (I use a Flowmaster Delta 40) will reduce lower frquency sound output, a straight-through glasspack will reduce higher frequency sound. Which is why I use both at the same time; glasspack up front, chambered near the exit.

I would also go with a universal muffler from Summit and try to get the db's of your race car to 90 at WOT. That's still too loud and can still lead to hearing loss, depending on your race length.

These are all excellent suggestions. I have a friend who owns a muffler shop so I stopped and he had a basically brand new muffler than someone took off their car as soon as they bought it because they wanted something louder.

Used some flex pipe and some adapters, basically like wake74 above, and it quieted the car about 8dB which is huge! Equally important is that it changed the tone and it no longer sounds like a race car sitting in my garage. It just sounds like any other car. A louder than normal car but not offensively loud like it was.

So that was a success. However, the back pressure causes the motor to run pretty rough. Almost to the point that it stalls. It runs better once warmed up but still not normal. I don't actually care as long as this isn't going to cause other problems down the road. What's everyone's thoughts on that? I'm going to try some of the other suggestions to see if they might work better.

I have some crushproof hose on order so that should address the CO.

@Mr_Clutch42, 90dB at WOT? I can try but that will be tough. There was a lot of creative measures taken on the spot last year at Laguna to keep it below the race only raised level of 103dB for our class. But the uniqueness of Laguna was part of the reason because normally WOT is 96-97dB.

I wear Hearos ear plugs (reduction around 30dB) and while I can't hear a worker when they are standing next to the car trying to tell me something (until they yell and tell me I forgot the dang sticker on my car so I can't run), I hope it's giving me some pretty good protection.

Is it a 2 or 4 stroke engine?

4 stroke. GSX_R 600 motor

I think bigger diameter flex pipe attached to your system by a tapered pipe (think megaphone) routed to a factory muffler designed for a high HP application would prevent the change in running condition of your car. My amateur interpretation of the stuff I've read says that would be about the same as your stock system hitting open airspace.

Intially our D Sports Racer was quite loud, 104 db, some development work got the noise level down to a reasonable level without any power loss. With the inlet restrictors run in F600 not sure if the loud exhaust is actually doing anything for you?

Tom

Some of the grow op guys out here bury a big 20 gallon drum underground to act as a muffler for their generators, a wee pipe back up to atmosphere and it's real quiet.

Or so I am told.

Tom1200, it's probably not doing anything, except maybe sounding cool. There are a lot of guys who have access to a dyno and have been testing for years. I shouldn't make any assumptions so I can test sometime when I put this car on a dyno though that won't be until next year I'm sure.

MrJoshua, I'm concerned that a high HP muffler would be loud as they often are but maybe not on a standard truck/suv application. Maybe as you and unevolved mentioned I might just need a bigger muffler. That and I need to test the bucket of water method.

SkinnyG, yea I bet that would REALLY work well. Course I have to get HOA approval just to put up a fence or deck or expand my driveway a few feet so I'm sure people would be out with pitchforks if I dig a hole and bury a barrel claiming rust in the ground or who knows what. I really need to move but that's going to take time and have bigger life priorities.

Our HOA just has a president and a treasurer. Not much to add here, but thanks for the reminder not to move to a subdivision. I'd have a hard time holding up my middle finger for that long, even if I switched hands occasionally.

What you need is a couple of other car guys on the block to distract the grievance-filers.

Zookie wrote: So that was a success. However, the back pressure causes the motor to run pretty rough. Almost to the point that it stalls. It runs better once warmed up but still not normal. I don't actually care as long as this isn't going to cause other problems down the road. What's everyone's thoughts on that?

Thoughts? It doesn't make sense. A 600 bike motor should run fine on an automotive muffler, especially if it's for a larger vehicle. Sounds like you have something else wrong. What kind of power does it make, 100 HP? Any decent car muffler should attenuate that and not make it run poorly.

Zomby Woof, you are right, it makes about 100hp. The thing is I don't know what kind of car the muffler came from. Just something my buddy handed to me. Wasn't even dirty it was so new. It is definitely this muffler causing the issue though because as soon as I remove it from the flex pipe (I don't have it fully clamped so it's easy to remove while car is running) or if I remove the entire flex pipe from the cars race muffler it almost instantly goes back to running like normal.

The other thing I tried was using just the flex pipe and no muffler. Car runs normal but it's, of course, as loud as with no flex pipe.

Maybe I just need a bigger muffler? The muffler he gave me did match my race car muffler at 2" so pretty small car it likely came from.

I can take some videos if it would help though it's sounding more like I just need a bigger muffler. I hope.