Which Muffler? Dynomax, Magnaflow, M&K - Dyno Charts

[mikedsilva]

I've recently put together a 3.0 and had it run on the dyno, to establish performance.
I'm at the stage I need to figure out which way to go for a muffler and there seem to be a few different theories.

Current setup is a set of European Headers 1 &5/8.
Muffler is M&K GT3 Sport (loud). I also purchased the baffled tips.

In the graph, the bottom line is the muffler with the baffled tips.
Middle is the Muffer with open tips.
Top line is with the M&K muffler removed.

Induction is EFI with 42mm throttle bodies from RHD Engineering | Porsche Bolt on ITB Kit
Pistons are CP 10.2
Cam is Webcam 464/465
I see some people are using the dynomax with a crossover... There is also a dynomax 17231, which I believe has straight perforated tubes, that pass through the muffler, so no cross over.

Which is the better way to go? Car will be a street car.. and I definately don't want it to be louder than my M&K.

[msmall215]

What are the specs on your motor, RoW or US spec and what year? Did you change anything other than induction?

Your results are consistent with mine which was that the M&K was fairly constrictive for a lightly modified motor. The guy who built my muffler is a gentleman named Hoover who runs a place called Turbohoses in California (https://www.turbohoses.com/turbohosessss.htm). I'm not sure the exact muffler he used, but he achieved zero loss of hp between open exhaust and muffled, with no drone as its a single center out with a custom tip. Shoot him an email at hooverc@turbohoses.com, he's extremely knowledgeable and loves his craft, and may be able to help steer you in the right direction.

IMG_4394 by Michael Small, on Flickr
IMG_4391 by Michael Small, on Flickr
IMG_4393 by Michael Small, on Flickr

[mikedsilva]

hi Mike,
very interesting muffler. What headers are you running? So you had yours dyno tested before and after? How is the sound/noise level?

Mike

[msmall215]

Originally Posted by mikedsilva

hi Mike,
very interesting muffler. What headers are you running? So you had yours dyno tested before and after? How is the sound/noise level?

Mike

It's certainly unique...almost similar to the old 550s back in the day. I'm running SSIs. I had mine dyno'd with the M&K, with no muffler, and then with this muffler, all without touching the tuning map. This week, it's going on the dyno for tuning to the new muffler.

Here is the plot for the M&K (blue) vs no muffler (red). You can see that the power loss was across the board, not at the top or bottom.
IMG_3375 by Michael Small, on Flickr

I'll have the new charts this week for M&K vs open exhaust vs new muffler. As far as sound, the car is still in California and I'm in Philadelphia, but from the videos that have been sent to me, it's very civil at idle, and really screams when you get on it. The note is deeper and smoother than the M&K. The M&K reminded me of a muscle car in some ways, which was a nice note in itself, but as you said, it's loud. The new muffler also showed no drone at any point.

[mikedsilva]

Very good.. cannot wait to hear. Have been in touch with Hoover..

[porschenut]

I'm curious about the difference between the Dynomax and the Magnaflow. I know the Dynomax is aluminized steel, and the Magnaflow is SS, but is there any other difference besides the price?

What's needed to get these installed? Some welding obviously, but where do you get the flange(s) that mates up with the cat or headers?

[MBruns]

I am going to test a few options in the next couple of weeks, one will be the Dynomax vs. a GT3 Cup Car muffler we run on our 3.8 race car when we need vs. open center out. The engine testing will be a 3.0 based 3.6 10.5 twin plug pump gas on PMO carbs.
Mike Bruns

[mikedsilva]

Originally Posted by MBruns

I am going to test a few options in the next couple of weeks, one will be the Dynomax vs. a GT3 Cup Car muffler we run on our 3.8 race car when we need vs. open center out. The engine testing will be a 3.0 based 3.6 10.5 twin plug pump gas on PMO carbs.
Mike Bruns

hi, do you know which Dynomax you will use? I see some are a cross over, and some are straight through?
I believe the 17231 is a straight through (the perforated tubes run parallel to each other).

[mikedsilva]

How good does this sound.

https://www.facebook.com/turbohoses/videos/2285463078398206/

[manbridge 74]

Sounds pretty good. Sort of a subdued SCART muffler sound.

Find it hard to believe it wouldn’t have an effect on power. It would also be nice to see A/F ratio changes with all three as some retuning of WOT fueling could pick up some lost power over open exhaust.

[Coastr]

Originally Posted by mikedsilva

How good does this sound.

https://www.facebook.com/turbohoses/videos/2285463078398206/

Plus flameage

You should keep an eye on the Db levels with whatever direction you want to go. If you decide to go to lakeside one day they might turn you away if it's too loud.

[MBruns]

17231 is what I am going to test

[mikedsilva]

Was I right in thinking that the 17231 has 2 straight through, perforated tubes?

[MBruns]

It is a perforated straight through, It's reported they work very well, on our 3.8 race engine the Cup muffler hurt it less than 5 hp over the open system center out, and didn't change the jetting, and that is the best muffler I have ever tested on the engine dyno, so we will find out.
Mike Bruns

[david.avrahami@]

you should explore MONTY mufflers from your own country...amazing quality free flow selection for our air cooled cars.

[stownsen914]

Originally Posted by MBruns

It is a perforated straight through, It's reported they work very well, on our 3.8 race engine the Cup muffler hurt it less than 5 hp over the open system center out, and didn't change the jetting, and that is the best muffler I have ever tested on the engine dyno, so we will find out.
Mike Bruns

Mike - do you know what the Cup muffler brought the db level down to? Measured 50 ft from trackside (the method most tracks use, I believe).

[MBruns]

We tested with it and they didn't have a problem with the level, the next day we went to our open system and it was fine too, some days give different results, cloud cover,wind etc.. The cup muffler sounds awesome on the 3.8
Mike Bruns

[Tom_in_NH]

Mikedsilva's muffler looks like it is based on a vibrant center-outlet muffler. Although not obvious in the attached photo, there is an inlet on each end of the muffler. Around $260 at Jegs.

[msmall215]

Originally Posted by Tom_in_NH

Mikedsilva's muffler looks like it is based on a vibrant center-outlet muffler. Although not obvious in the attached photo, there is an inlet on each end of the muffler. Around $260 at Jegs.

Tom, the green car above with the muffler is mine, and that looks like the ticket.

[KTL]

The 17231 is a straight through, non-X muffler. Flow direction is shown in the catalog as parallel but guys have run this muffler in opposing flow directions with no problems.



The muffler has two perforated tubes running straight through and the tubes are separated by fiberglass packing