Muffler flow test

found this today

http://www.broaderperformance.com/muffler%20flow%20test.htm

This is a chart of popular performance and a few stock type mufflers I have tested on our flow bench. These were all the most popular mufflers sold and installed at a local exhaust shop. Straight pipes have been tested and are used to compare these mufflers to "potential" flow of a muffler. When running a performance muffler on the street there are many more things to consider then just good flow. For instance pleasant tone and enough sound reduction to avoid any "unwanted" attention from local authorities. One thing to keep in mind is how restrictive tailpipes are. You can have a great flowing muffler but if your tailpipes are restrictive you may not be getting any gain from loud, high flow, and not to mention sometimes "expensive" mufflers.

 

That's amazing how the Max Flow has the same flow as the same size straight pipe... almost too good to be true.

 

I think it is very telling that the Flowmaster 2 1/2" two chamber was identical to the Cherry bomb with a 2 1/4" inlet and 2 1/2" outlet.
The Hooker Max flow passes twice that! Wow!

 

I wonder how it sounds????

 

heres an update:


2"
2" Straight Pipe..........................................283 CFM

2 ¼”
2 ¼” Straight Pipe.......................................365 CFM
2 ¼” Inlet/outlet Maremount Cherrybomb Vortex.. 298 CFM
2 ¼” Glasspack (no louvers inside)................274 CFM
2 ¼” Tail Pipe (typical passenger car)............268 CFM
2 ¼” Inlet/outlet Thrush CVX.........................260 CFM
2 ¼” Inlet/2 ½” Outlet Cherry Bomb Turbo......249 CFM
2 ¼” Cherry Bomb.......................................239 CFM
2 ¼” Inlet/outlet California Turbo.......................229 CFM
2 ¼” Inlet/outlet Flowmaster (3 chamber).........229 CFM
2 ¼” Inlet/Dual 2" Outlets (used in OEM style Dual Exhaust)... 183 CFM
2 ¼” Inlet/2 ½” Outlet Maremount Super C (stock type)... 149 CFM
2 ¼” inlet/outlet round glasspack (with inward punched louvers) (installed in reverse direction....... 141 CFM
2 ¼” inlet/outlet round glasspack (with inward punched louvers)....... 133 CFM


2 ½”
2 ½” Straight Pipe...........................................521 CFM
2 ½” Inlet/Outlet Hooker Max Flow.....................521 CFM
2 ½” Inlet/Outlet Dynomax Ultraflow Bullet.......512 CFM
2 ½” Center Inlet/offset Outlet Borla Turbo.........373 CFM
2 ½” Inlet/Outlet Hooker Aerochamber...............324 CFM
2 ½” Inlet/Outlet Maremount Cherry Bomb........298 CFM
2 ½” Cherry Bomb ..........................................294 CFM
2 ½” Inlet/Outlet Magnaflow.............................284 CFM
2 ½” Inlet/Outlet Dynomax Superturbo..............268 CFM
2 ½” Inlet/Outlet Gibson Superflow...................267 CFM
2 ½” Inlet/Outlet Flowmaster (2 Chamber).........249 CFM

 

Who cares what it sounds like? I need performance from a performance car. If I don't like the sound it makes I can always change gears.

 

Can someone provide some theory to these flow numbers in context of performance optimization? What I am thinking is ... say I have an engine that has the right carb which is a 650 CFM. Would the prefered muffler flow choice for a dual exhaust setup be exactly 325 CFM, or would more flow provide improved performance, or maybe less to optimize the scavenging effects etc.?

Maybe it is not that simple ... or maybe it is

 

I have always found exhaust systems to be a facinating subject. I dont think cfm@15"wc is the entire story though. That says little about pressure waves and scavanging which are important characterisics to consider. Maintaining velocity through the system is also important. Its too complex to be understood simply by comparing how much air can be pushed through a muffler although that may be a major consideration.

 

Good thing i found some HP numbers

The results in HP order:
1.Flowtech Warlock (open) 374.2 hp/ 333.1 tq
2.Bassani Real Street 373.7 hp/ 333.8 tq
3.Hooker Maxflow 373.5 hp/ 333 tq
4.Borla XS 373.3 hp/ 332.6 tq
5.Magnaflow 372.8 / 332.5 tq
6.MAC 372.3 hp / 331.5 tq
7.Flowtech Afterburner 372.3 hp/ 330.1 tq
8.Hooker Aerochamber 372.1 hp/ 330.4 tq
9.Bassani 372 hp/ 333.5 tq
10.Spintech 371.6 hp/ 332.2 tq
11.Edelbrock Performer RPM 370.9 hp / 331.3 tq
12.Borla XR1 370 hp/ 334 tq
13.Flowtech Terminator 369.5 hp / 331.3 tq
14.Dynomax Ultra Flo 369.4 / 333.2 tq
15.Flowmaster 369.4 hp / 331.8 tq
16.Flowtech Warlock 366.3 hp / 325.3 tq
17.No muffs 365.2 hp / 330.1 tq

Sound Off in Quietest to Loudest (Decibels):

1.Borla XS, 80db at idle, 90db at 2,000 rpm, 110db at WOT.
2.Hooker Maxflow, 80db at idle, 90db at 2,000 rpm, 120db at WOT.
3.Magnaflow, 82db at idle, 91 at 2,000 rpm, 114db at WOT.
4.Flowmaster, 82db at idle, 93 at 2,000 rpm, 115db at WOT.
5.Flowtech Warlock, 83db at idle, 92 at 2,000 rpm, 112db at WOT.
6.Dynomax UltraFlo, 83db at idle, 94 at 2,000 rpm, 113db at WOT.
7.Borla XR1, 83db at idle, 96db at 2,000 rpm, 118db at WOT.
8.Bassani Street, 83db at idle, 96db at 2,000 rpm, 120db at WOT.
9.Edelbrock RPM, 84db at idle, 93db at 2,000 rpm, 118db at WOT.
10.Bassani Real Street, 84db at idle, 96db at 2,000 rpm, MAX. (120+db).
11.Flowtech Afterburner, 86db at idle, 94db at 2,000 rpm, 115db at WOT.
12.Flowtech Terminator, 86db at idle, 94db at 2,000 rpm, 119db at WOT.
13.Hooker Aerochamber, 87db at idle, 94db at 2,000 rpm, 114db at WOT.
14.SpinTech, 87db at idle, 97db at 2,000 rpm, 116db at WOT.
15.MAC, 87db at idle, 98db at 2,000 rpm, 119db at WOT.
16.No Muffler, 91db at idle, 103db at 2,000 rpm, MAX. (120+db).

http://forums.stangnet.com/archive/index.php/t-392314

 

Interesting, on a list of 17 configurations, there is a difference of less than 10 HP and only 3 ft.lbs of TQ. And this only shows peak so its not the whole story. But with numbers that close I would want the one that simply sounds the best. And look at the flowmaster, while not flowing nearly as much cfm as the open pipe, its now making more power and torque. This illustrates what I was eluding to.

 

What engine and specs?
Listing of components?
What RPM was max power with each muffler and what was the size of the mufflers.
To me this list tells less than the first list.

 

i lost the correct link

i'll try and see if i can find it.

 

i noticed that too, i was just about to throw my 40S away, not anymore

 

Yep, pick the sound you like and leave it at that. You won't notice much difference in power. Although many claim that at higher rpm the Flowmasters start to drastically loose power.