Quiet muffler that doesn't kill power, does one exist?

[175K911]

Originally Posted by RarlyL8

The muffler Steve is using looks to be from a late model 911GT3. Not an inexpensive solution, and when the valves open, not quiet. Very cool street system though.

And note the crossover between the two tips too.

[mjshira]

Steve stop being a tease...

[esample]

Originally Posted by tobluforu

Dansk sport, 2 in, 1 out if your car has ssi's. It's not quiet and it's not loud at all-kind of perfect.

I have one of these for sale, if you're interested!

[Steve W]

Originally Posted by mjshira

Steve stop being a tease...

lols, more,

[Tom '74 911]

Steve -

Is this something you are going to market, or a one off experiment? It looks interesting.

Tom

[MotoSook]

Vacuum actuated to open less restrictive path at WOT. Now squeeze a couple of turbos in there

[911st]

Where is the vac going to come from to open them?

Or are they held closed with vac?

[Jaskas]

Originally Posted by 911st

Where is the vac going to come from to open them?

Or are they held closed with vac?

Cool system, but this was the thing i was wondering also.

I was planning to plug my other outlet with a electric cutout.

[911st]

If it is open sitting on the bench and he has to close it manually it probably is held closed with manifold vac at idle and cruse. Then opens under WOT when vac drops.

That is my guess.

[RarlyL8]

If it is open sitting on the bench and he has to close it manually it probably is held closed with manifold vac at idle and cruse. Then opens under WOT when vac drops.

That is correct. There are a few other add-ons that manipulate this system. I have been playing with these for a few years now as I would like to produce an active exhaust system for the 930.

[911st]

Brian,

Could be fun.

On a turbo, other than noise control, do you think it might add to the power band anywhere over a great open muffler or zork.

I can see an actual advantage on a NA car where it might broaden the TQ range.

The best.

[RarlyL8]

Nope, on a turbo it's all about sound. Nothin' better than that turbo whistle and burbles on decel. With the 911 it must be a tuned system that adds performance and a cool sound.

[kojo911]

I'm happy w/ these: Hushpower Pro Series mufflers

I'm running them on my twin turbo, so not a good comparison. They're light, quiet and inexpensive.

[911st]

Nice!

Great set up for a turbo car.

However, using that layout as a starting point for a NA car.

I think I would try putting the mufflers on the tail pipe side which would make for a longer secondary tube and would work best with a long tube design. Then would add a cross over in the center just before the mufflers.

A cross over should help with noise level, should reduce the back pressure potential from the muffler sections, and from reports by experts that know more then me, should make for a wider TQ band.

Do not know how quite it would be though.

I like.

Just a guess.

[silver911rdb]

Gary,

Did you figure out a solution? I'm in the same boat with my car. I just found out that Limerock dropped their max db by 1 db. They'll be enforcing 87db max for BMW track days and 88db for PCA DE events. I just purchased a 911 with a 3.4 and megaphones and need to find a quiet muffler. I like the looks of Tom Butlers RSR rally style muffler. 2 rear outlets similar to M&K's but it also has the capability to cap the 2 outlets and use the 3rd exit pipe from the side pointing downward. i was searching for a picture of his muffler but I couldn't find it. Does anyone know if this style will be too restrictive on a 350hp engine when capped? Also, i don't see this style for sale anywhere. It looks like it might be a custom make

[GaryR]

Look at the $200 muffler thread, i'm using the biggest Magneflow 2-in 2-out they have in 2.5" pipe. Not sure if it fits or how quiet, will post as soon as I get my SPL (iPhone) db readings!

[GaryR]

I should add this though I haven't had the car outside for a db test on my iPhone. Custom pipes using a Magneflo 12568.


Initial mounting


Finished with all non SS parts heat painted.

[silver911rdb]

Gary, nice work. So what do you think, will it'll be quiet enough? Also, do you know what the distance is between exhaust pipes (center to center)? I'm wondering if that muffler is too long or will it fit within my exhaust cutouts on my bumper.

[GaryR]

Originally Posted by silver911rdb

Gary, nice work. So what do you think, will it'll be quiet enough? Also, do you know what the distance is between exhaust pipes (center to center)? I'm wondering if that muffler is too long or will it fit within my exhaust cutouts on my bumper.

Other than stuffing baffles in the out pipes there is nothing else I can do, it's a BIG Muffler! The guys at Magnaflo seem to think it will do it. I even pointed the pipes down 30 degrees as I read in Grassroots it's one of many "tricks" to dissipate sound. It's ONLY for DE's at one track so if it needs baffles too so be it. I would start with one and then add the other if needed.. There's no way to know if next year's race will be muffled or not, but if not I need it and also for any NASA races that happen at LRP..

[gumba]

I ran a Flowmaster 80 w/George's european headers on our 3.4 race car. I registered 92 db at Infineon. I ran small baffles for the street. The baffles probably cost me about 5+ h.p. at the top end and lowered the sound level by at least a few db's. I made my own baffles using perforated steel and wrapping it with s/s wool. You can control the sound level by how many wrappings of the s/s wool.