Muffler Tests

[ptuomov]

How one could claim no drone for a generic/universal muffler without knowing the specific exhaust pipe and cabin resonances is a mystery to me.

[1980RS]

How one could claim no drone for a generic/universal muffler without knowing the specific exhaust pipe and cabin resonances is a mystery to me.

I have an old pair of the old Slowmaster mufflers om my race car 0 drone and the car is just as quick with the exhaust open or closed. On my street car I run a pair of Hooker Areo chamber mufflers as people claimed they have no drone, bought a pair used for $25 put them on the car and no drone, they sound great also. Worst muffler I have ever owned that have a lot of droning in the car were my Slowmaster super 40's they suck.

[73c34me]

I have flowmaster super 40s no drone ever. Can’t say if they are coating me horsepower.

[modok]

How one could claim no drone for a generic/universal muffler without knowing the specific exhaust pipe and cabin resonances is a mystery to me.

The vehicle may not have any cabin, and yet the the exhaust system still may drone.

That's what "I" would mean if I said it.
Just muffler design itself, IMO you need three chambers to avoid setting yourself up for that kind of trouble, and it's not just me, but a lot of luck involved either way.

Black widow..... Worst of both worlds? or best of both worlds? I like it less after trying one.
Original flo-pro is still the winner for simplest viable design IMO. Not that simplest is best but it is a good place to start.

[MetricMuscle]

Black widow..... Worst of both worlds? or best of both worlds? I like it less after trying one.

Might you expound on your experience? I'd like to use a single muffler for a 400hp Infiniti v8, it would greatly simplify the installation.

[jsgarage]

Sorry for the rant, but muffler testing is one of my long-held hot buttons. It seems that all published muffler tests I've ever seen involves the gain or loss of engine power. That entirely misses the point: there's no earthly reason to ever run ANY muffler on ANY motor vehicle except to soak up excess combustion noise to a socially acceptable level. And the problem with doing that is, you get different results on a given muffler with different engines of the same basic size & type. You also get different results with the exact same engine if you change its cam, compression or header design, or especially if the testing method used is slightly different.

Real testing involves a dB meter, often the now-obsolete Radio Shack device, and the SCCA, most sound-restricted race tracks and even the infamous So-Cal Noise Police all use a specific published method. It involves a dB meter set on the 'B' scale, 'slow' response, positioned 50.0 ft from the edge of a track (or vehicle), 2-1/2 ft off the ground on a camera tripod (no human is touching the meter) and exactly 90 degrees perpendicular to the side of the vehicle. Some specify a gear and an rpm range, or they check during qualifying so sand-bagging is difficult.

To my knowledge, there is NO AGREED UPON STANDARD METHOD for sound testing any engine in a concrete dyno cell, so engine dynos are out for meaningful sound tests. Nor is there an agreed upon method for sound testing a vehicle on a chassis dyno if the vehicle is in an enclosed building even with an open roll-up door. Dunno- likely Ford & GM have their own in-house tests but the giant aftermarket muffler builders cannot duplicate their tests and such factory results seem to be top secret anyway. Maybe because few buyers are interested enough to even mention exhaust noise.

That's probably why all we get are essentially the rare, stand-alone muffler-and-power tests done at one shop, or meaningless verbal sales descriptions like "powerful", "throbbing" or "deep-tone". Getting true muffler comparisons today is as impossible as it was 60 years ago in the days of power-producing(?) aftermarket duallys, Echo-cans, glass-paks vs steel-paks and home-made split-manifolds on high-winding 6's that broke house windows and caused birds to fall out of the sky. Which probably did as much to influence public opinion against modified motor vehicles as fatal high school crashes did pre-seat belts.

[modok]

How hard is it to tack in a muffler and test it? A muffler cost 60$ or so. Buy all the different kinds and find your favorite.

[ptuomov]

On a race car, I think the objective is to pass the external noise limit and keep the car from droning so badly that the driver with a helmet and ear plugs can't drive it. This while optimizing the power to weight ratio.

In a street car, the question is much more interesting. The best solution is not the quietest, obviously given our cultural preconditioning. However, it is not obvious what kind of sound the car should make. I've been operating under the following sound-quality objectives:
(1) The dominant frequency of the exhaust noise should be proportional to the engine rpm.
(2) The sound pressure or overall volume should be monotonically increasing in power delivered.

See any weaknesses in those objectives?

[gruntguru]

. . . .
(2) The sound pressure or overall volume should be monotonically increasing in power delivered.

Perhaps torque rather than power?

[travis]

How hard is it to tack in a muffler and test it? A muffler cost 60$ or so. Buy all the different kinds and find your favorite.

That's why I own something like 10 pairs of mufflers now lol. Sometimes you just have to try different styles to find what you like.

Aerochambers are still one of my favorites, but I've been running a pair of Cherry Bomb Salutes (cheap magnaflow knock off's) on a 10:1 351w in one of my trucks and have been really happy with them. Surprisingly quiet for a muffler you can see right through, yet have a nice bark when you step on it.

[ptuomov]

. . . .
(2) The sound pressure or overall volume should be monotonically increasing in power delivered.

Perhaps torque rather than power?

I thought about that I think it should be power. The car should be louder at 450 ft-lbf and 7000 rpm than at 500 ft-lbf and 3000 rpm. So it’s power in my opinion that should be monotonically related to sound pressure (to the maximum extent possible).

[F-BIRD'88]

How hard is it to tack in a muffler and test it? A muffler cost 60$ or so. Buy all the different kinds and find your favorite.

Or cut a few up and make your own custom built mufflers.

[MetricMuscle]

How hard is it to tack in a muffler and test it? A muffler cost 60$ or so. Buy all the different kinds and find your favorite.

I like the sound of a Flowmaster but I don't think a single Super 44 will flow enough.

What didn't you like about the Black Widows? Which model did you try?