Exhaust options

[george schilling]

Hi guys. I'm finally getting started competing with the new to me RF84. We'll be wanting to compete in the upcoming solo nation tour in San Diego and I'll need to pass a very strict sound limit of 93db. I'm currently running an open exhaust. What are my best options?

[Barry Ott]

I ran a coast fab muffler on my Reynard. I had them make me a custom one, I don't remember the exact dimnsions but it was just a little longer than one of their off the shelf mufflers. Something like 4" OD, 2 ID, 20" long (the actual muffler section, not counting the tubing on the ends). Worked great, *always* under 93 dBa. I was sound chief for our region, so I had to be good and quiet, and I always was. For the VD/Honda, I bought a used smaller model for our local events now that we and Nationals are at 100 dBa. Note that our sounds supps were almost copies of the SD region supps.

Barry

[ewcmr2]

With the 13" coast fab muffler we are over 93dB in San Diego. We'll be testing a supertrapp this weekend.

[Dick R.]

With the 13" coast fab muffler we are over 93dB in San Diego. We'll be testing a supertrapp this weekend.

Will you be running both the coast fab and the SuperTrapp in series?

Dick

[-pru-]

With the 13" coast fab muffler we are over 93dB in San Diego. We'll be testing a supertrapp this weekend.

Regarding the Coast Fab muffler, how old is it / age of the packing? I ask as those of us using this type of muffler at the 2011 Nationals were recording dBs in the mid to high 80's. Most of these muffler were less than two years old...

[mwizard]

I am using a Supertrap with no baffles and it seems to be ok. You could add baffles at an event if needed. Good flexibility.
Mark

[ewcmr2]

Will you be running both the coast fab and the SuperTrapp in series?

I hope not! I hope the supertrapp can get the sound down to <93dB by itself.

[ewcmr2]

Regarding the Coast Fab muffler, how old is it / age of the packing? I ask as those of us using this type of muffler at the 2011 Nationals were recording dBs in the mid to high 80's. Most of these muffler were less than two years old...

Coast muffler was new summer 2011. We're most of you using the 13" version or longer ones?

[loudes13]

In my experience the bolts always rusted/stripped making swapping the plates a pain. Basically it became an open glass pack after a year. Too many heat cycles and condensation for their cheap hardware to handle it.

[ewcmr2]

In San Diego the Supertrapp with bout 15 discs got us a visit with the sound steward, 94.x dB.

6 discs made us safe at 85-86dB.

[Dick R.]

In San Diego the Supertrapp with bout 15 discs got us a visit with the sound steward, 94.x dB.

6 discs made us safe at 85-86dB.

What length SuperTrapp? (I'm guessing either a 10 inch or a 17, either with 2 inch inlet).

Also, what rev range?

Thanks,

Dick

[ewcmr2]

What length SuperTrapp? (I'm guessing either a 10 inch or a 17, either with 2 inch inlet).

Also, what rev range?

10", 2" in, 4" discs.
Revs? High... I'd guess 58mph in a 66mph gear. ChaseCam data/video acquisition system is in the future.

[Jim Garry]

I used one of the mufflers on the webpage below. The manufacturer will tell you which one for FF. Not cheap but it works great. I was never above 90 db in any weather condition and the muffler steals almost zero HP.

Before that we ran the Supertrapp for many years. Bolts rusted and broke and the internal fiberglass had to be replaced every three years. And still I was close to being over db unless I used just a few plates, which robbed a ton of HP.

I always thought Burns and Coast Fab were identical but if you can't get down below 93, then maybe they are different. Or maybe your engine has a different set up which makes it louder (but it shouldn't result in a huge db difference).

http://www.burnsstainless.com/ultra-lightmufflers.aspx

[Don Elzinga]

Mount the muffler as close to the collector as you can. If you put it right on the end with no tailpipe, it will be less effective.

Don

[george schilling]

Eric, did you notice a power drop?

The Burn 2 stage stainless looks good. Bill M is also using it and is happy.

Thanks guys for the responses.

[mwood]

The car I just got has 13-14" Coast Mfg on a HyTech header...all gorgeous stainless. I don't care if I get DSQ'ed every run at SD, I'm not messing with the exhaust...it is too pretty LOL

[kjchristopher]

I always thought Burns and Coast Fab were identical but if you can't get down below 93, then maybe they are different. Or maybe your engine has a different set up which makes it louder (but it shouldn't result in a huge db difference).

http://www.burnsstainless.com/ultra-lightmufflers.aspx

They are the same. Eric is using a short one. Probably too short.

[jdp526]

I am running a lightweight muffler on a 2L that I bought on Ebay for $45 including the shipping. It weighs apprx 3.5 lbs. It does have a removable baffle that I have not used. Our club has a 93dB limit at one facility and I have not received any complaints.

[george schilling]

I am running a lightweight muffler on a 2L that I bought on Ebay for $45 including the shipping. It weighs apprx 3.5 lbs. It does have a removable baffle that I have not used. Our club has a 93dB limit at one facility and I have not received any complaints.

This one looks pretty nice and certainly worth testing. Was this a one off deal or is that the "new" selling price?

I ordered a Super Trapp 10" stainless today, about 3.5 lbs. $171 shipped from Summit. We'll test it in San Diego Sunday.

[Dick R.]

This one looks pretty nice and certainly worth testing. Was this a one off deal or is that the "new" selling price?

I ordered a Super Trapp 10" stainless today, about 3.5 lbs. $171 shipped from Summit. We'll test it in San Diego Sunday.

George,

I run the 10 inch Super Trapp with no plates but I have NO idea what the sound level is. Probably over 93 dB. Subjective driveway testing indicated that about 12 plates reduced the sound a lot but you may need fewer.

Dick

[jdp526]

The muffler I bought on Ebay is made overseas and its supposedly a carbon fiber can with ss endcaps and outlets. Looks like the rivets could be drilled out if baffling ever needs replacing.
There are all kinds of inexpensive mufflers on ebay.

[Craig Henry]

Hi everyone,

I have a new SuperTrapp 4” OD X 18.5” long muffler on the shelf with a stack or two of extra discs (along with higher quality & longer stainless attachement bolts.) Will this meet the sound restrictions or should I purchase one of the Burns units?

Thanks in advance for the help.

Craig

[RudeDude]

Hi everyone,

I have a new SuperTrapp 4” OD X 18.5” long muffler on the shelf with a stack or two of extra discs (along with higher quality & longer stainless attachement bolts.) Will this meet the sound restrictions or should I purchase one of the Burns units?

Thanks in advance for the help.

Craig

Craig,

The beauty of the SuperTRapp is in its adjustability. If the sound is too loud, you will run less discs and it will be quieter. However, the less discs you run, the more restrictive the exhaust system will be. If you have to run fewer than 12 discs to make the sound restriction, you may want to consider an alternative.

Hope this helps.

[Craig Henry]

Hi Sho,

Old fart and long dormant autocrosser trying to get back out. Ran a couple different S2’s in CM way back when but needed a 24” SuperTrapp to keep the decibels reasonable… without choking the engine by running under 18 discs. Looking for someone that has run the 18.5” model on a Kent to provide some feedback as to the number of discs needed to meet the sound restrictions. If less than 12 – 18 discs are needed I’ll likely purchase the Burns unit for my FF to be safe. Some of the posts here noted issues with the 10” model but no word about the 18.5.”

Sorry for not being more clear.

Craig

[george schilling]

I ended up buying the 10" Super Trapp. It came with 12 discs and I have run all of them for a total of 16 runs and have never blown over 90db. I glad you resurrected this post as it reminds to order another set of discs tomorrow to try adding some more. You should be fine with the 18".

[RudeDude]

Hi Sho,

Old fart and long dormant autocrosser trying to get back out. Ran a couple different S2’s in CM way back when but needed a 24” SuperTrapp to keep the decibels reasonable… without choking the engine by running under 18 discs. Looking for someone that has run the 18.5” model on a Kent to provide some feedback as to the number of discs needed to meet the sound restrictions. If less than 12 – 18 discs are needed I’ll likely purchase the Burns unit for my FF to be safe. Some of the posts here noted issues with the 10” model but no word about the 18.5.”

Sorry for not being more clear.

Craig

Craig,

I beg your pardon for my ignorance. I should have read your post more carefully....

Hope to meet you at some event this season somewhere. NEDiv at the Meadowlands in May?

[Jim Garry]

Hi Craig,

Really glad to see you'll be getting your car out soon!

In the Citation I ran the 10" SuperTrapp and never had a problem. But sometimes I ran only 5 or so discs at Devens which has a very strict control. Eventually I bought the Burns unit.

The bottom line is that the ST will keep you within any requirement we see at Solo events. It will however steal power. But if you're just trying to drive around the course to get yourself acclimated again (and to make sure nothing falls off the car), then might as well save money and stick with the ST.

If you get to the point where you feel you can use the extra tenth or two (more or less?), then consider going with the Burns unit.

BTW, at some point, the fiberglass in the ST wears out and you'll need to replace it.


Hope to see you soon. Too bad we've lost Seneca Army Depot.