Think ALL Flowmaster mufflers lose power? Think again...
#22
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So, are we concluding that the Flowmasters that flow don't muffle, and the Flowmasters that muffle don't flow?
I'm one of the guys that removed a 2-chamber Flowmaster (non-crossflow design) and picked up 45 rwhp on a 305 rwhp combo.
I like my Magnaflow because it's quiet and 700 rwhp car doesn't gain anything when I remove it. To me, THAT's impressive. It flow's AND muffles. I had good luck with SLP and the Aerochamber crossflow also. SpinTech sucks, though. +3 mph in the quarter when removing a single 3.5".
Mike
I'm one of the guys that removed a 2-chamber Flowmaster (non-crossflow design) and picked up 45 rwhp on a 305 rwhp combo.
I like my Magnaflow because it's quiet and 700 rwhp car doesn't gain anything when I remove it. To me, THAT's impressive. It flow's AND muffles. I had good luck with SLP and the Aerochamber crossflow also. SpinTech sucks, though. +3 mph in the quarter when removing a single 3.5".
Mike
I'm gonna have to raise a big BS flag on you losing 45rwhp with a 305rwhp setup, that's total non-sense. Oh, well maybe there was some apples wedged in the outlet or something? Or shop rags? Give me a break man, that's rediculous.
I sure as hell hope you don't lose power with a STRAIGHT threw muffler
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#23
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Thanks for the compliment
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#24
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We are concluding that the single chambers are not power robbers. They're also "race" mufflers, they're suppose to be loud. It's the nature of the beast. Although the sound level seemed to sound similar to open pipes, it's MUCH more refined, and actually a pleasure to hear. Never met anyone that heard the car and didn't like it.
When we start talking about how "refined" something sounds, this all becomes a matter of opinion anyway. I prefer my 9 second car to be as quiet as possible, and with a smooth idle too. To each his own. . .
1989 Firebird coupe, stock weight: 360 cid SBC, 8.5/1 compression, AFR210 heads - Race Ready porting, 847 cam (234/242@.050), Victor Jr intake, Holley 750, SLP 1 3/4" shorty headers, TH700R4, Vigilante converter (locked), 3.42 gears.
Single 3" in / dual 2.5" out Flowmaster: 305 rwhp, 12.70 @ 109 mph
Muffler removed: 345 rwhp, 12.30 @ 113 mph
Single 3" in / dual 2.5" out SLP muffler: 350 rwhp, 12.20 @ 114 mph
When I first put together that combo, the car didn't perform like I thought it should. I chased my tail for a while, changing the headers and torque converter. Those helped, but it still didn't run like it should. One day at the track, I decided to disconnect the muffler and the next pass was nearly a half second and 4 mph faster! I went to the dyno and verified the 2 chamber Flowmaster was killing the power. This was several years ago, so a bunch of people were pretty shocked at the outcome. It's not that unreasonable, when you consider alot of guys are gaining upwards of 25 rwhp by bypassing one running camshafts with alot less overlap than mine. More overlap means that backpressure is that much more critical.
With the new muffler, it eventually went 11.96 at 114.5 in better weather with the accessory belt removed, then later with a short block swap (383 with 11/1) went 11.0 @ 123 mph.
Mike
#25
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Ok, so maybe we should call them "race attenuators" or "race resonators" if their sole purpose in life is not to muffle, but to make the sound "more refined".
When we start talking about how "refined" something sounds, this all becomes a matter of opinion anyway. I prefer my 9 second car to be as quiet as possible, and with a smooth idle too. To each his own. . .
When we start talking about how "refined" something sounds, this all becomes a matter of opinion anyway. I prefer my 9 second car to be as quiet as possible, and with a smooth idle too. To each his own. . .
It's all very well documented. David at Thunder was there for it all and probably remembers if you want verification.
1989 Firebird coupe, stock weight: 360 cid SBC, 8.5/1 compression, AFR210 heads - Race Ready porting, 847 cam (234/242@.050), Victor Jr intake, Holley 750, SLP 1 3/4" shorty headers, TH700R4, Vigilante converter (locked), 3.42 gears.
Single 3" in / dual 2.5" out Flowmaster: 305 rwhp, 12.70 @ 109 mph
Muffler removed: 345 rwhp, 12.30 @ 113 mph
Single 3" in / dual 2.5" out SLP muffler: 350 rwhp, 12.20 @ 114 mph
When I first put together that combo, the car didn't perform like I thought it should. I chased my tail for a while, changing the headers and torque converter. Those helped, but it still didn't run like it should. One day at the track, I decided to disconnect the muffler and the next pass was nearly a half second and 4 mph faster! I went to the dyno and verified the 2 chamber Flowmaster was killing the power. This was several years ago, so a bunch of people were pretty shocked at the outcome. It's not that unreasonable, when you consider alot of guys are gaining upwards of 25 rwhp by bypassing one running camshafts with alot less overlap than mine. More overlap means that backpressure is that much more critical.
With the new muffler, it eventually went 11.96 at 114.5 in better weather with the accessory belt removed, then later with a short block swap (383 with 11/1) went 11.0 @ 123 mph.
Mike
1989 Firebird coupe, stock weight: 360 cid SBC, 8.5/1 compression, AFR210 heads - Race Ready porting, 847 cam (234/242@.050), Victor Jr intake, Holley 750, SLP 1 3/4" shorty headers, TH700R4, Vigilante converter (locked), 3.42 gears.
Single 3" in / dual 2.5" out Flowmaster: 305 rwhp, 12.70 @ 109 mph
Muffler removed: 345 rwhp, 12.30 @ 113 mph
Single 3" in / dual 2.5" out SLP muffler: 350 rwhp, 12.20 @ 114 mph
When I first put together that combo, the car didn't perform like I thought it should. I chased my tail for a while, changing the headers and torque converter. Those helped, but it still didn't run like it should. One day at the track, I decided to disconnect the muffler and the next pass was nearly a half second and 4 mph faster! I went to the dyno and verified the 2 chamber Flowmaster was killing the power. This was several years ago, so a bunch of people were pretty shocked at the outcome. It's not that unreasonable, when you consider alot of guys are gaining upwards of 25 rwhp by bypassing one running camshafts with alot less overlap than mine. More overlap means that backpressure is that much more critical.
With the new muffler, it eventually went 11.96 at 114.5 in better weather with the accessory belt removed, then later with a short block swap (383 with 11/1) went 11.0 @ 123 mph.
Mike
I'm not gonna argue with you. I would like to believe that you have no reason to lie about it, so I'll give you the benefit of the doubt. I'm sure stranger things have happened.
#27
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Don't get me started on the 3.5" single in/out offerings by Hooker Aerochamber and also Spintech. . .
Mike
#28
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I don't think that most cars will gain anything near 45 rwhp at the 300 rwhp power level by removing their flowmaster muffler. I think that's gonna be a pretty isolated incident in general. Did anyone call Flowmaster and ask them WTF? 45 HP you think someone would have...
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Thank you for this! I have heard the same thing about the 1 chambers too. It pisses me off because people are going off hearsay about the 80 series, assume that it goes for all Flowmasters, and then spread it around as gospel. I also have Flowmaster TD's (in pic) with the 1 chambers and I love the power and sound. Not a day goes by I dont get compliments on it. I also put down the #'s in my sig with this setup.
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Just so happens I still have the stock catback and crossflow 80 series muffler. I plan on testing it vs open headers on the dyno if I ever get done with my 4L80 swap. Not sure if I will end up going true duals or cutouts, I just love how it sounds lol.
#37
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And the stock catback complete with 2.75" pipe was only worth a 7 or 8rwhp loss vs a 3.5" cutout with a mild cam and slightly ported heads with full boltons, Hmmm. I don't see how the flowmaster is any worse than the stocker looking at these pics. Anyone care to enlighten me?
#38
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And the stock catback complete with 2.75" pipe was only worth a 7 or 8rwhp loss vs a 3.5" cutout with a mild cam and slightly ported heads with full boltons, Hmmm. I don't see how the flowmaster is any worse than the stocker looking at these pics. Anyone care to enlighten me?
#39
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Because they both force the exhaust gasses to make multiple hard 90 degree or more turns or force them around objects in the flow path. Anything that makes the gasses have to bend, hit, or go around slows velocity and kills flow potential. 7 or 8 rwhp loss with stock cat-back versus a 3.5" cutout in a H/C car is BS. Something is wrong there. Big time. The stock muffler is very restrictive, but it flows enough to support the desired out-put for the stock vehicle while also passing sound-requirements.
Last edited by JRENIGAR; 08-23-2014 at 06:50 AM.