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My quest for quiet, free flowing mufflers

beags86 said:
how much power does your engine make?
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Well... it should be over 500 at the crank but have not had it on the dyno yet. Sept 22nd is the day.

mrk5 said:
I dont know if it's been covered, but when it comes to the quiet part, the length of the tailpipe will help a lot.

I keep telling my wife I want to put a Black Widow Neighbor Hater muffler on the C10. She doesn't find the idea as amusing as I do. :rotfl:
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I have tailpipe going all the to the back exiting under the bumper. Yeah I will stay away from that muffler.

Bent77 said:
I have one neighbor I want to heat...
we use to load the converter on the trans brake on the drive way. That okay, right? :D
Click to expand...
Hell yeah! Tell the neighbors you are "troubleshooting" the transmission and not sure why its doing that
 
Had the fire dept show up once. Lots of smoke!
 
More data I found. Look at the HP on the dyno. This is for 2.5" which is more restrictive than the 3" muffler.

The Mufflers
MAKE MODEL Part No. COST
SUMMIT Turbo 630125 $14.75
THRUSH Magnum Glasspack 24214 $16.50
THRUSH Boss Turbo 17718 $23.95
HOOKER Competition 21006 $25.95
DYNOMAX Super Turbo 17733 $28.50
DYNOMAX Race Magnum 24215 $31.95
HOOKER Super Competition 21106 $35.95
SUMMIT Fully Welded 630325 $38.69
FLOWTECH Afterburner 50322 $39.95

MUFFLER FLOW TEST

MUFFLER Flow at 28-in H20
DynoMax Race Magnum 528.64 cfm
Thrush Magnum Glasspack 507.40 cfm
Summit Fully Welded 343.38 cfm
Flowtech Afterburner 342.20 cfm
DynoMax Super Turbo 333.94 cfm
Hooker Competition 232.46 cfm
Hooker Super Competition 320.96 cfm
Summit Turbo 331.16 cfm
Thrush Boss Turbo 297.36 cfm

MUFFLER Idle dB WOT dB
DynoMax Super Turbo 89 123
DynoMax Race Magnum 94 133
Flowtech Afterburner 92 124
Hooker Competion 92 122
Hooker Super Competion 90 125
Summit Turbo 89 124
Summit Fully Welded 92 125
Thrush Boss Turbo 90 123
Thrush Magnum Glasspack 92 128

DYNO TEST
All mufflers were dyno-tested on a 355-cube SBC with 10.0:1 compression, Air Flow Research 190 aluminum heads, a CompCams 292 hyd. a Victor Jr. intake, a Holley 750-cfm double-pumper, and 1 5/8 Headman headers.


MUFFLER HP TORQUE 2,500-6,000rpm Average
Hooker Competition 397.4 381.1 286.8hp/351.9 lb-ft
Thrush Boss Turbo 407.1 384.9 292.1 hp/357.5 lb-ft
DynoMax Race Magnum 409.5 394.3 298.8 hp/366.9 lb-ft
Flowtech Afterburner 409.7 391.2 294.8 hp/361.7 lb-ft
Thrush Glasspack 409.5 389.8 297.7 hp/365.3 lb-ft
Summit Turbo 411.5 386.3 291.5 hp/357.4 lb-ft
DynoMax Super Turbo 412.7 387.2 292.6 hp/358.6 lb-ft
Hooker Super Comp 413.8 387.2 292.8 hp/359.0 lb-ft
Summit Fully Welded 415.4 390.7 295.6 hp/362.4 lb-ft
 
The Summit fully welded actually made the best power.
 
For $28 bucks, that’s pretty awesome

Of course so are the Dynomax race magnums
 
From this chart Dynomax Ultra-flo looks impressive too. I called Dynomax today and they said that center tube on the center/offset design won't affect anything on flow. He said they flow just as good as the offset/offset "s" design. He also mentioned the 3" muffler does not neck down at all internally. He also suggested the Ultra-flo's for being quiet since they pack more sound absorption material in them and said sometimes they are almost as quiet as the ST. Nice to call tech's that know their product. I still think the Super Turbo is the way to go for what I need. The flowmaster 70 is also tempting but its like twice the cost and I need 2 of them.

mufflertest-silentpower2-jpg.348429
 
Do before and after sound clips. Maybe a dB test if you’re able, I’m curious
 
Will do. Just installed Sound Meter on my android. Looks to be free. I'll do before and after. My fabricator won't be available for 10 days.

I wonder if its possible all my Magnaflow sound material was blown out by a trip to Moab and high RPM back when I had the 496. 496 BBC + headers + 4.88 gears + 75mph, + no OD. Probably less than 2000 miles on those mufflers.
 
They lose packing anyway, so hard to determine how much
 
Few things cackle like a single plug iron head Chrysler....
 
Update-

Well.... I got the 3" Dynomax Super Turbo mufflers and had them installed in place of the Magnaflows. Both Magnalfow and Dynomax mufflers almost equal in size.

Its almost the same loudness at idle. I measured with a sound app and the decibel reading is almost the same on either setup. 85 decibels. It does seem a tad quieter driving it around but still has some rasp at higher RPM at WOT. Definitely not happy with the results in my quest to quiet it down.

So... basically I just threw some money at some new mufflers / labor and got the same result as the old setup. I think the dual 3" design does not help matters. I'd probably be better off with a dual 3" into a 4" single, long muffler.
 
Can't remember if I mentioned it before or not but I run a Magnaflow 12909 muffler on my silverado with long tubes and a high flow cat and it's every bit as quiet as stock but deeper. It's a straight through 3.5" muffler that's as big as the factory muffler. Might be worth looking in to.
 
Is there room to put a 2nd muffler or resonator on each side? Did you look into Medium Duty mufflers from Walker? If you could adapt to 3.5", something like walker 22551 would be much quieter than a "performance" muffler.

Or slap some cats up front!
 
There is no room on the passenger side for any cat or resonator with the NP205 being clocked and the exhaust having to bend around that tucked up away from the rocks. I know a cat or resonator would help, just no room for that. If the muffler was shorter then maybe a resonator before that but they are LONG and take up lots of room. After the muffler, it bends up and over the axle and fits between the tight space between the tank and the frame. A stockish engine with a single exhaust and cat can't really compare to a dual 3" exhaust with an aggressive 406ci setup. A single exhaust or H pipe would definitely help quiet it down more but I'm kind of tired throwing money at this and may just live with it for now. Just disappointing these mufflers did not help like how I thought they would.
 
Those would definitely not meet the "free flowing" requirement mentioned in the title, anything that fits inside the pipe is not going to be good for that.

The reviews are great, "quieted my 3.5" pipes way down".....maybe that's because they choked them way down to about a 1" ID pipe and a few orifices to squeeze between?
 
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