Exhaust build: Quiet 3" muffler

[Amuro Ray]

Any suggestions?

[dradernh]

My car is at 95dB, and since Lime Rock Park has gone insane with its sound restrictions, I asked my shop to create another option for me, with V-band clamps for easy-on, easy-off. I received this as an update last week:

"We have a straightforward, simple fix for the exhaust sound level. The tech guy at FloMaster seemed to be a seasoned and serious professional (20 years at FloMaster), and knew what he was talking about. I have a muffler, and turn down on its way that he is confident will bring the sound level down to 85dB."

If you'd like, I can get the name of the tech, or you can probably get the same service just by calling them up.

As an aside, 85dB is 1/10th the sound level of 95dB.

[jakermac]

If you're looking for another data point, my exhaust is a full 3" mandrel bent system with headers. I have a 3" spun metal cat, 3" x 18" Vibrant resonator, 3" x 14" Coast Fab racing muffler, and a Magnaflow 14329 3" muffler. On my 325is, it's about 90-92db. Our autocross site has a 92db limit, so I am quite paranoid. Exhaust still dropped 49 lbs off the weight of the OEM setup (my primary motivation for the change).

[Das Bullitt]

Jakermac, are you single 3" or dual 3" plumbed?

[S50ti]

I have a magnaflow 14x9 3"in/out. No cats or resonators, ebay long tube headers. 86dB...sounds great and isn't obnoxiously loud. I think it was $30

[jakermac]

Jakermac, are you single 3" or dual 3" plumbed?

Single 3"

[m3mobbin]

Bit heavier than using a resonator for the center section, but my 3" setup works well for the street.

http://forums.bimmerforums.com/forum....php?t=1506995

[vjlax18]

I talked to Flowmaster years ago and they told me to put the muffler under the car. The longer the pipe after the muffler, the quieter it would be. I didn't follow their suggestions though. I just put a turn-down on the tailpipe with a normal clamp. I would angle the turn-down 45* away from the sound meter and it always did the trick.

[Amuro Ray]

I'm having my long tubes connected to a burns collector and then to this single 3inch pipe. Sound clips if you guys have them.

[bennyfizzle]

I'm having my long tubes connected to a burns collector and then to this single 3inch pipe. Sound clips if you guys have them.

um. that's going to be really loud

[odortiz]

why not run the exhaust in to the passenger compartment?
:-D

[OppLock1]

I have aa headers to two magnaflow mufflers (14 and 18 inch). I can easily drive it on the streets without being noticed. Drone is close to none and on the tracks its decent, nothing that turn heads really.

There is also no rasp and it happens to be rather very low and deep sounding.

I was skeptical about going magnaflow, but it ended up very nice and on the cheaper side vs e.g. Borla.

[bennyfizzle]

Raceland longtubes--->long vibrant canister style resonator--->magnaflow 3"

[ame]http://www.youtube.com/watch?v=L1Pb8n2rChk[/ame]

Not a fan of how it sounds, but it's not super loud. Drones pretty bad with no interior though.

Going to a vibrant 3" and a turn down.

[xvxax]

I talked to Flowmaster years ago and they told me to put the muffler under the car. The longer the pipe after the muffler, the quieter it would be. I didn't follow their suggestions though. I just put a turn-down on the tailpipe with a normal clamp. I would angle the turn-down 45* away from the sound meter and it always did the trick.

I don't like this because it kind of skirts around the basic purpose of sound metering in the first place: keeping sites and tracks. With that said I'm running a 24" muffler and a 18" resonator and I measured 86db at 100 feet without a turn down. Turning directly down could drop that too.

[Amuro Ray]

I don't like this because it kind of skirts around the basic purpose of sound metering in the first place: keeping sites and tracks. With that said I'm running a 24" muffler and a 18" resonator and I measured 86db at 100 feet without a turn down. Turning directly down could drop that too.

Brand and sound clips?

[Steve J.]

Run mufflers in series. 2 smaller mufflers one after the other will usually reduce overall db level more than one "larger/longer" muffler.

As far as the turn downs, there are some "muffled" turndowns as well, but be careful with where it points...if its very close to the ground and it just bounces off of it, it won't help you any....and if you think you can point it to one side to avoid the db reader, they move it randomly

When all else fails - add a turbo!

[Amuro Ray]

I have a magnaflow 14x9 3"in/out. No cats or resonators, ebay long tube headers. 86dB...sounds great and isn't obnoxiously loud. I think it was $30

Bit heavier than using a resonator for the center section, but my 3" setup works well for the street.

http://forums.bimmerforums.com/forum....php?t=1506995

Raceland longtubes--->long vibrant canister style resonator--->magnaflow 3"

http://www.youtube.com/watch?v=L1Pb8n2rChk

Not a fan of how it sounds, but it's not super loud. Drones pretty bad with no interior though.

Going to a vibrant 3" and a turn down.

Thanks for the clips guys, I can't watch videos at work, but this will give me something to watch at home.

[BMW4LIFE]

Run mufflers in series. 2 smaller mufflers one after the other will usually reduce overall db level more than one "larger/longer" muffler.

As far as the turn downs, there are some "muffled" turndowns as well, but be careful with where it points...if its very close to the ground and it just bounces off of it, it won't help you any....and if you think you can point it to one side to avoid the db reader, they move it randomly

When all else fails - add a turbo!

I am going to LRP on Monday (86db now) and I am not sure if my de-baffled stock e36 exhaust will pass. Loud is very subjective but to me it ain't that loud but the sound meter may tell a different story.

I bought some muffler pipe elbows from advance auto and they are a few inches from the ground when attached to the muffler.

So my question is how far from the ground should the down turns be to quiet the exhaust????

[dradernh]

I am going to LRP on Monday (86db now)...

It's the lift for braking on the front straight that will make or break your setup. (No pun.) If you're too loud, adjusting your management of that transition will allow you to pass the test, and you can still have plenty of fun as long as you're not looking to set a personal lap record.

My last time at Lime Rock, I ran the first session with no issues. Next session, I received a black flag for 95dB pretty quickly, with the club's pit director asking me what exhaust change I'd made between sessions. His comment was that my lift hadn't been noticeable to him in session one, whereas in session two it gave him the old head-snapping-around-saying-WIH-was-that!?! effect. Beats me as to what was going on, since there was no change on my part.

I listened to my new-for-LRP Flowmaster muffler today for the first time; not 100% sure it's going to fly, but I hope to have the track give me a reading at next Tuesday's unmuffled test & tune day.

The whole thing is a total PITA as getting an 85dB reading next Tuesday doesn't mean I'll ever get the same reading again, even with the exact same components on the car. The vagaries of dB readings, along with the extremely low dB requirements, means that a stock muffler may be what's necessary to ensure compliance.

[BMW4LIFE]

It's the lift for braking on the front straight that will make or break your setup. (No pun.) If you're too loud, adjusting your management of that transition will allow you to pass the test, and you can still have plenty of fun as long as you're not looking to set a personal lap record.

My last time at Lime Rock, I ran the first session with no issues. Next session, I received a black flag for 95dB pretty quickly, with the club's pit director asking me what exhaust change I'd made between sessions. His comment was that my lift hadn't been noticeable to him in session one, whereas in session two it gave him the old head-snapping-around-saying-WIH-was-that!?! effect. Beats me as to what was going on, since there was no change on my part.

I listened to my new-for-LRP Flowmaster muffler today for the first time; not 100% sure it's going to fly, but I hope to have the track give me a reading at next Tuesday's unmuffled test & tune day.

The whole thing is a total PITA as getting an 85dB reading next Tuesday doesn't mean I'll ever get the same reading again, even with the exact same components on the car. The vagaries of dB readings, along with the extremely low dB requirements, means that a stock muffler may be what's necessary to ensure compliance.

Thanks for the input. You are correct, LRP has become a PITA. What a shame!

Anyway, I am picking up a stock e36 exhaust just in case.

[endoforce5]

I've used a spiral muffler insert from Speedway with great results. It is about 15" long and slips into a straight section of the pipe. It costs ~$20 and quiets the car considerably. As to the exact dB's, your results may vary but it is surprisingly effective, light and cheap.

[OLD MAN]

Dradernh ever interested in your results - we have been under the gun with our E21 since we got it running. We are on our third attempt to get the dB's down to 90 or so. Now that we are building a bigger motor I am thinking it will be even harder. We currently have a Flowmaster Hushpower Pro with turn down on it, still too load so we added a Cat to the system which helped a lot, but still need more.

[jimmypet]

I bought a brand new Magnaflow 24" x 8" x 5" and a 90° turn down that I used to keep in a box just for Lime Rock.
I'd swap it in just for those dates so it had almost no wear / deterioration which made it quieter longer.
That combination passed sound there, but it was a few years ago when the DB limit was only stupid.
As has been posted above, pointing away from the sound measurement point is huge.
As Steve J posted, beware of pointing straight down at the ground. Reflections will kill you.

I have not been to Lime Rock since they have completely lost their minds.
Screw that place.
I don't know why you guys even go there.
Spend your money at tracks that want your business.

[PCarroll]

We've been running 3.5" exhausts with two Borla XR1s in series. We have no trouble passing the restrictions at Calabogie and Tremblant. Problem is, the muffler in the center section only lasts a couple of weekends. It just can't take the heat up close to the engine. The rear muffler seems to survive quite well.

[RRdawho?]

2 magnaflow mufflers + turbo makes the car pretty quiet on my end