Racers: what are you using for mufflers?

Hi, guys.

Putting the finishing touches on the 190 Cosworth to finally get started racing this season. The car needs a new exhaust as the old one is rusted and heavy. Considering all the sound restrictions we see lately, I want to make a smart choice so I don't get turned away at tech.

My car is basically an E30 M3 in disguise: 2.3L twin-cam engine putting out about 200 hp. The exhaust is a single 2.5" stainless steel pipe from the headers back. I'm looking for a 2.5" stainless steel muffler that won't be too restrictive, yet will pass sound tech.

From past projects, I've started my search with Magnaflow. They only have one 2.5" "race series" muffler ... but the body is just 6" long. That doesn't seem like it would be quiet enough. Any brands/models I should consider? Should I add a Supertrapp tip to the muffler so I can quiet it down as needed? What do you think?

Any of the magnaflow round mufflers should work. They are a straight through design so they won't be restrictive.

If you find the muffler is not quiet enough throw on the smallest length 2.5" resonator from Vibrant (or otherwise suitable supplier) you can find. Just my personal preference but I love the sound of a resonated exhaust with louder mufflers. You get a great, aggressive sound that doesn't sound like a lawnmower - unless you're into that sort of thing. However, another vote for Magnaflow. I was going to recommend a Monza exhaust, cut to fit but that would most likely be to heavy for all out race car.

+1 for the Magnaflow straight-through exhausts. I'm running something similar, woulda gone with the Magnaflows but I didn't discover what's better about them until after I ordered - the layer of steel packing that makes the fiberglass harder to blow out and cuts sound a bit more.

The Vibrant resonators are good for cutting sound without adding much restriction. Another good option for that is an auger-type resonator.

9" Dynomax Race Bullet $19 + ear plugs http://www.summitracing.com/parts/wlk-24250/overview/

When the Magnaflow is too loud, I use a stainless Walker Dynomax oval race muffler. The regular ones vibrate apart too quickly in race use, but the stainless one is holding up nicely.

Giant Purple Snorklewacker wrote: 9" Dynomax Race Bullet $19 + ear plugs http://www.summitracing.com/parts/wlk-24250/overview/

Are the earplugs for the sound meter at the track?

There's an upcoming trackday event at Laguna Seca with a 90 dB sound limit. Yes, you read that right. At that low a level, car induction noise along can exceed that. Have to keep the rich neighbors happy that they moved in... next to a track...

Anyway, I've been happy with Dynomax mufflers, though even they might be iffy with a 90 dB level. Regardless of muffler, for sound limiting, it's very important to keep the exhaust pipe diameter at 2.5" or less, at least near the muffler.

kb58 wrote:

Giant Purple Snorklewacker wrote: 9" Dynomax Race Bullet $19 + ear plugs http://www.summitracing.com/parts/wlk-24250/overview/

Are the earplugs for the sound meter at the track? There's an upcoming trackday event at Laguna Seca with a 90 dB sound limit. Yes, you read that right. At that low a level, car induction noise along is going to exceed that. Have to keep the rich neighbors happy that they moved in next to a track...

I race at the Glen, Summit Point, Pocono, VIR, Mid Ohio and NJMP. No sound meters anywhere except Lime Rock and they have special uncorked days... so I only go then.

It's only that way because of the cramped location of the side exit exhaust. I hate it. Even with ear plugs I get tincture after a 35 minute race. My new race car will feature a magnaflow 40 series because it has to exit the rear in the OE spot per the rules so... I have plenty of room to work in a bigger muffler back there as the factory unit was HUGE.

Use a 90 degree turn down at the end that you can adjust. When you get to the track, figure out where they put the sound meter, and point th4 exhaust outlet away from there. That will help with noise a bit. Beware, some places will move the meter to mess with people :)

I would look at what some of the street legal catback systems are using, since 90db is the normal max limit of a street vehicle. You may lose some ultimate power, but one doesn't want to waste a bunch of track time fighting adding mufflers to their car.

Also, as an ersatz test, you can get a sound meter app for your smart phone and measure the sound at the same distance they'll measure at to get an idea of how close you'll be to meeting regs.

Hope this helps!

Yep a 90db limit is common. There's a site where you can find the sound test procedure used on the Nurburgring which you can copy to do a DIY test.

I also got a Dynomax SS muffler (with an OBX 18x5.5" straight-through resonator), I just hope the packing stays in.

FWIW, I had terrible luck using with a SuperTrapp muffler. It was either too loud or too restrictive, and ended up pushing the stuffing out through the baffles... A big thumbs-down for them.

kb58 wrote: FWIW, I had terrible luck using with a SuperTrapp muffler. It was either too loud or too restrictive, and ended up pushing the stuffing out through the baffles... A big thumbs-down for them.

Yes, they are mostly useless anymore. When they first came out, it was an interesting concept, time has moved on though.

My turbo car has both length dynomaxx bullets in my pipe diameter in series in the mid pipe, and then a borla xs at the back. For no-sound events I can drop the rear muffler and take more than half the exhaust weight out.

But I'm an even bigger fan of the mufflers I made for a fellow miata driver. They're surprisingly easy to make.

(sorry for the potato picture quality)

Yes those are aluminum, and so is the rest of the exhaust I made for that car. with all 3 mufflers going all the way back it weighs as much as the midpipe + 1 loud terrible sounding muffler, and it super duper quiet. Like hardly louder than stock quiet.

And yes, if you ask nicely I can make you some stainless ones.

I run dual Lobaks AKA Moroso Spiral flows on the RX7 after dual RacingBeat resonators. They cut it from bleeding ears to "Damnit that thing is loud" Adding to the noise is the fact that the exhaust tracts never join.

https://www.facebook.com/photo.php?v=10202225435105336&l=5936655558868716775

Giant Purple Snorklewacker wrote: My new race car will feature a magnaflow 40 series

What is a 40 series Magnaflow?

Thanks very much for the tips.

With no cat and twin Weber DCO 48s, the car will be loud to start with. I'll be racing at Tremblant and Calabogie, both of which have very strict sound regulations. Mosport, Watkins Glen, and NJMP don't seem to care. Still, I'd rather err on the side of caution and keep things quiet.

I've gotten lots of feedback from the BMW CCA CR crowd. The top two choices seem to be the Borla XR-1 Multicore and Hooker Maximum Flow. According to people who have supposedly "researched" this, these are the two that flow the best while still providing reasonable sound attenuation.

Based on price ($240 vs. $73), I decided to try the Hooker.

The hooker weighs approximately 50 pounds, and sounds completely awful on a 4 banger. I ran one with a long glass pack on my old supercharged car. You know how the first year of ken blocks fiesta sounded? Yeah exactly like that, but without the anti-lag. The hooker does come out the quietest in the v8 magazine tests.

Hooker does score well on low sound and high flow, and they have that cool angular look...they don't use steel packing like Mangaflow does though. And 50lbs is A LOT. The Walker/Dynomax I got at about the same size is nowhere near that.

I was exaggerating a bit. It was certainly heavier than the borla xs of about the same size I have now. It felt like they use really heavy gauge steel for the case.

Interested to see how this turns out. I've been contemplating going with a larger exhaust for the +1hp it'll provide, but I LOVE the 'OEM' exhaust on my pile.

On the turbo rotary, I run 3" from the turbo back to a single Borla XR-1. Quiet enough to pass state inspection as long as you take it to the right place. Not sure why people say rotaries are loud. They just need a turbocharger.

1988RedT2 wrote: On the turbo rotary, I run 3" from the turbo back to a single Borla XR-1. Quiet enough to pass state inspection as long as you take it to the right place. Not sure why people say rotaries are loud. They just need a turbocharger.

Yeah because you're cheating! A turbo is a muffler, you effectively have 2 mufflers on your rotary!

That being said I have header to y pipe with two 2.5" racing beat mufflers and was last recorded at 98db non turbo.

1988RedT2 wrote: On the turbo rotary, I run 3" from the turbo back to a single Borla XR-1.

Is that the "Multicore" or the "Sportsman." I have no idea what the difference is, save for a price difference of $60-70 bucks.

Moroso Spiral flow in the middle and cheap $12 turboII a foot of so down then pipe to the end.