Additional Muffler for FM

[GT-Subject]

Hi all,

One of our area race tracks now has a 92 dB limit - my FM is 104, any ideas on adding an additional muffler or resonator to my current stock setup so that I can reduce my exhaust dbB to 92? And how would I mount all of this additional exhaust setup?

Thanks in advance for your thoughts......

[CGOffroad]

Throw something like this on the end of exhaust. Experiment with quantity of plates to reduce noise as needed

Supertrapp 444-2503 4" Diffuser Disc Assembly

https://www.amazon.com/Supertrapp-44.../dp/B003P8I0I8

[BeerBudgetRacing]

Learn where on each track the sound is measured and add a bend pointing the other direction.

[GT-Subject]

Throw something like this on the end of exhaust. Experiment with quantity of plates to reduce noise as needed

Supertrapp 444-2503 4" Diffuser Disc Assembly


https://www.amazon.com/Supertrapp-44.../dp/B003P8I0I8

Thanks for your comment, I have tried a Supertrapp and i don't get enough dB reductions to meet the 92 dB. plus I find that using 5 or more Supertrapp plates kills the horsepower and I have to change my car setup.

[GT-Subject]

Learn where on each track the sound is measured and add a bend pointing the other direction.

Thanks for your reply. Unfortunately, the track has a rule that they test your car on the paddock and move the dB tester around the car to find the loudest point, so sadly the solution I use at other tracks will not work at this particular track.

[Lotus7]

Just an empirical thought, but 104 down to 92 seems nigh on impossible without so much performance loss that you'd be miserable driving it.
Rotaries are tricky devices where sound is concerned, there are plenty in scca that are ear-splitting yet apparently legal. Maybe find out what others are doing.
As an aside, testing at presumably max throttle in the paddock standing right beside the car seems grossly unfair to you guys.
What track is this, (surely not Mosport?), and maybe there's other choices elsewhere?

[J Leonard]

Maybe a photo of what you have now. A number of FM's for sale on here have photo of rear of car. 104 to 92 does sound next to impossible in any practical way.

[10rmotor]

Good luck getting down that far. I don't think you'll be able to get that low without severely restricting Hp and spending a ton of money on mufflers that won't melt due to the extreme exhaust heat of a rotary. The exhaust sound is hard enough but I'm thinking you may also have induction noise as well. On our older DSRs with flat slides, the slide throttles rattled in the bore and caused a bit of additional noise we had to worry about. Laguna was the worst.

[BeerBudgetRacing]

One of our area race tracks now has a 92 dB limit - my FM is 104, any ideas on adding an additional muffler or resonator to my current stock setup so that I can reduce my exhaust dbB to 92? A

Good luck getting down that far.

Living in Commifornia as it's commonly called, we are on the forefront of squashing everything fun. The legal limit here is 95 db !
https://www.californiacarlaws.com/exhaust-noise/

So someone or something at that track is outta whack... Someone is trying to shut them down.

[old 59]

Tremblant

[Lotus7]

Tremblant

that was my first thought, but he said "our area track" and then saw he's in Burlington

[old 59]

It’s an assumption on my part Ian, but I believe that’s the track Paul is referencing.

[kea]

Thanks for your comment, I have tried a Supertrapp and i don't get enough dB reductions to meet the 92 dB. plus I find that using 5 or more Supertrapp plates kills the horsepower and I have to change my car setup.

You have it backwards on the Super=trapp. The more plates you run, the louder it gets with less horsepower issues.
Also, a 5" version will work better for this application ( and a FF2000) then a 4", with less HP loss per noise drop..
Still,you may need a packed-core muffler to get to 92.

[DanW]

Noise level is cumulative from all sources.

In addition to what Keith advises, you likely would need to fab up an airbox with the inlet pointing away from the dB meter, just as you would with the exhaust outlet. Understand that even gear noise from your Hewland will add to the noise level.

[GT-Subject]

Thanks for all of your comments, sadly, I think the amount of work required for me to be able race my FM at Tremblant is not worth the investment at this point in time.

[Lotus7]

Thanks for all of your comments, sadly, I think the amount of work required for me to be able race my FM at Tremblant is not worth the investment at this point in time.

Tremblant is one of the greatest tracks in North America.
If you haven't been, I urge you to rent something that is allowed to run there and just enjoy a day of driving it.
(Is there still a drivers school operating there? I did Russel there a long time ago).

[GT-Subject]

Tremblant is one of the greatest tracks in North America.
If you haven't been, I urge you to rent something that is allowed to run there and just enjoy a day of driving it.
(Is there still a drivers school operating there? I did Russel there a long time ago).

Fortunately, I have many laps there in my FM and in other race cars prior to the noise dispute with the neighbours. I do plan on renting a closed wheel race car sometime this coming year so I that I can race there at least a few more times!!!! Sadly, the Russell School closed a while ago and all of the race cars have been sold off.

[David Clubine]

There are several issues with the noise at Tremblant and obtaining the 92DB. First and foremost is the meter is 'roving' and if could be left or right, on a corner or middle of the straight.

The other issue is the surrounding mountains, and cloud (or lack of) cloud cover plays havoc with the readings....

Having fielded at times 4 or 5 cars a weekend there, I am pretty much done with all of that. Thank-you to the 5 new cottage owners across the river from turn 1.... I can't run a car with an open muffler and I can't take a dip in the river to wash up anymore... lol

[Robins Ken]

Tremblant area is like Vegas. 3 days and you never want to see the place again. Unless you are from Montreal and have a Ferrari.

Suburbia is closing in on racetracks. Mosport will be one of the next. The good thing there is the terrain around it is horrible. Quarries etc. IMO that's the only thing keeping development/greed away. For now anyway.

I bet Watkins Glen does not get too uppity about noise. The track has to be the largest contributor to the local economy.

[Lotus7]

Mosport will be one of the next.

Hopefully Ron Fellows knew something we didnt when he invested so much into the place.
Road Atlanta on the other hand ... :-(

[Robins Ken]

Hopefully Ron Fellows knew something we didnt when he invested so much into the place.
Road Atlanta on the other hand ... :-(

The ownership group has done a fantastic job.
2 downers. 5 months of winter and IMSA screwing them by dropping the GTP cars. Pit lane too short. Gotta make room for those Pro Mazda Miatas. Really?

For a N/E US regional guy. Still a must do. Friday test days are great value.

Cheers. KR.