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

[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.

My new exhaust with the Magnaflo #12568 monster 2-in/2-out passed no problem. My buddy with the same muffler on his 3.6 964 was borderline but they let him run. The sound guy was very cool, came around and discussed his findings and was pretty sure once the trees have leaves on them the borderline's will be fine. It's only DE days that are an issue, other than the fact I had to make up a new muffler it's no big deal.. I was told mine doesn't sound a lot quieter, just has a lower tone, which I believe is part of the equation.. and keep in mind I run tuned headers and an engine tuned to get every ounce of HP out of it with special cam and ignition timing (on all stock parts of course). I run at 4-6.5+K ALL the time!

[Jaskas]

Originally Posted by Steve W

teaser pics:

That exhaust looks so nice. Im dreaming of copying your idea.
What kind of noice it makes? Have you measured the noice level? Would you happen to a clip of the sound it makes?


I was wondering about the flow in the muffler? Is it like this:
(Black arrow when the valve is closed and white when open)



Is the crossover a modification done to reduce the drone? Did it help?

[RWebb]

no one has mentioned Monty yet, which is what I have, tho I think they cost about 2x what I paid these days

I'd love to have something that weighs a lot less (it is 16 lbs.); and once in A while I think it should be quieter on the fwy (but then I turn off the fwy and am happy)...

[whiterabbit]

I have a Monty as well. I really like the sound and its a good bit quieter than an M&K I have on my other 911.

The M&K weighs 9lbs so I guess about 7lbs less than the Monty,

[wachuko]

I need headers and some level of muffler for an SC that I want to make into an RS 3.0 narrow body...

So far I am reading these headers (Burh)



and the M&K Mufflers. These?



or these



Or what should I use? I just want a decently priced setup that will have headers and dual exhaust to the back...

[Steve W]

The crossover is original, nothing was changed internally. I don't know if that crossover was done for sound, flow, or both. I would suspect for flow first as we've dyno'd 911 race cars with an open exhaust making a bit more torque and power with a crossover vs without. I believe the perpendicular T of the crossover allows the pulse of the opposite bank to create a vacuum in the T, reducing the backpressure of the other bank.

No db measurements, but it is not anywhere as quiet as a stock car. I would describe it as 'controlled loud'. The sound is deep, healthy, and unrestricted. With headers, normally resonance and drone exists between 1500-2700 rpm with or without mufflers, then goes away after that. Similar with this setup but not as loud and noticeable when the valves are closed, then gets really quiet from 3000 rpm on, so the exhaust valves programmed to switch to full open, and as you pass 4500 rpm, it goes into a full incredible wail. When the valves are shut the overall sound level is reduced by about 6-8 db. A MSD rpm switch controls a OEM Pierburg vacuum solenoid from a 997 GT3, providing vacuum from a 944/964 vacuum canister to actuate the Pierburg exhaust valves. If you're ok with loud cars, driving on the street is fine and should not be enough to get you pulled over. Though, when you floor it, after 4500 rpm, the exhaust note is completely open and when you merge both exhaust banks together in the center, the acoustic coupling creates loud a high pitch wail. This is as opposed to an exhaust with separated outlets, such as megaphones with have a very loud but deeper note that is about half the pitch. When the valves are full open, a 30-40 mm gap between the intake pipe and outlet pipe on the larger pipe allows the muffler to remain as an expansion chamber to perform reactive noise attenuation, keeping the exhaust note similar to but just a few db short a track car with an unmuffled 2 into 1 tailpipe at high rpms. The sound at full throttle in the upper rpms is somewhere between a typical 911 race car with open exhaust, and a GT3 Cup car. The 997 Cup cars in fact use something similar to this muffler, just use the lower inlet and block off the upper inlets. Since they are 3.6-4.0s and run much higher compression, they have a bit louder and harder exhaust note.

The flow diagram you've detailed is exactly how it all flows.

I've tested cars with Monty's before, which are very well made, and although I wouldn't call the few test comparisons I've seen conclusive, I think there could be performing mufflers.

[RarlyL8]

Absolutely love that setup Steve. If I had time I'd develop one with packing material to make it more quiet.

Here you go wachuko:

[Canada Kev]

So, Steve, would you stop teasing us, please? How 'bout the rest or the story...

[Jaskas]

Thanks Steve for answering my questions!

I will propapably add some premufflers before the gt3 muffler if I go this way.

[wachuko]

Please, do share details. Brand, cost, etc. That is exactly what I am looking for...

Here you go wachuko:

[Joeaksa]

Originally Posted by wachuko

Please, do share details. Brand, cost, etc. That is exactly what I am looking for...

Wach,

Am guessing that the muffler in the photo is one of the old MK (Ben) styled muffler. If memory serves me correctly, Brian (Rarly) and Ben (MK) merged and now these are being sold by Brian.

[Steve W]

Last month in preparing a bunch of very high hp 3.2 track cars for Laguna Seca, AASE Motors put together an exhaust system off the headers that was so quiet, if you closed your eyes you would swear it was a stock car. Very strange sight to see a hardcore flared, caged, race car idle and roll around sounding exactly the same and as quiet as a stock 3.2. Track db level measurement was about 86 db vs the 105-110 db with open pipes. Dyno'd hp loss was minimal, about 5 hp around 5500, and 3 hp at 6700 vs wide open race pipes.

[ben parrish]

Steve, What mufflers were they using?

[wachuko]

Thank you. Do you have an email, phone #, or website link so I can find what the cost is and how to order?

Thanks again!!

Quote de wachuko

Please, do share details. Brand, cost, etc. That is exactly what I am looking for...

Wach,



Am guessing that the muffler in the photo is one of the old MK (Ben) styled muffler. If memory serves me correctly, Brian (Rarly) and Ben (MK) merged and now these are being sold by Brian.

[tobluforu]

M&K Exhaust - Manufacturers of Custom Exhaust for your Porsche

[wachuko]

Ok, MK that I can buy from Pelican. Cool.

M&K Exhaust - Manufacturers of Custom Exhaust for your Porsche

[Joeaksa]

Originally Posted by wachuko

Thank you. Do you have an email, phone #, or website link so I can find what the cost is and how to order?

Thanks again!!

Look at the signature on the post above:

RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds '78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar

Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8

[LJ851]

Originally Posted by ben parrish

steve, what mufflers were they using?

+1

[Bill Verburg]

Originally Posted by Steve W

The crossover is original, nothing was changed internally. I don't know if that crossover was done for sound, flow, or both. ....

The X-over is a classic drone/noise abatement strategy

look at the flow path, in at the top, where the combined flow of both banks pressures the containment vessel, there will be close to uniform pressure at all points w/i the containment. Flow will be out the bottom, sound waves are bouncing around all throughout the containment, the goal is for some of the peaks and valleys of the sound waves in the outlets to meet and cancel each other, similarly the internal perforated screens break up the sound waves, often there will be f/g or ss packing wrapped around perforated tube to additionally absorb sound waves, though that strategy appears to be missing in the muffler picture, The factory mufflers also incorporate shaped containment walls which reduce sound vibrations that are often set up in slab sided walls.

[wwest]

Coming soon.....2020?

Electronic anti-noise, out of phase, OPPOSITE phase, pressure wave generation inside the "muffler" housing.

Already in use in some venues, otherwise LOUD urban area emergency generators, etc.

Off or "ON" switch.