And note the crossover between the two tips too.

Steve stop being a tease...

Dansk sport
 

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

lols, more,

http://forums.pelicanparts.com/uploa...1294074675.jpg


http://forums.pelicanparts.com/uploa...1294074690.jpg


http://forums.pelicanparts.com/uploa...1294074705.jpg

Steve -

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

Tom

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

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.

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.

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.

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.

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.

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. http://forums.pelicanparts.com/uploa...1294242110.jpg

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.

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

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!

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
http://forums.pelicanparts.com/uploa...1301710869.jpg

Finished with all non SS parts heat painted.
http://forums.pelicanparts.com/uploa...1301711102.jpg

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..

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.

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!

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)

http://i216.photobucket.com/albums/c...1287700974.jpg

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

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)...

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,

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)

http://www.pelicanparts.com/catalog/...sch_header.jpg

and the M&K Mufflers. These?

http://www.pelicanparts.com/catalog/...t/mneb-trk.jpg

or these

http://www.pelicanparts.com/catalog/...2sport-lbl.jpg

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

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.

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:


http://forums.pelicanparts.com/uploa...1346473547.jpg

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

Thanks Steve for answering my questions!

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

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.

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.

Steve, What mufflers were they using?

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!!

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

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

+1

http://i216.photobucket.com/albums/c...1287700974.jpg

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.

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.