nuzee

iTrader: (2)

I was generously given an American Thunder catback system recently. I’ve read many posts about the FM being a lousy performer due to poor flow characteristics. Since I had a cut out already, I figured I’d install the FM for sound purposes. It does sound good. I noticed my Z responding better with the FM vs. stock system when the cutout was closed.

Anyway, last night I went to the track to test out my new Nitto DRs. I was running a very consistent 13.2s@105.6-7 mph. Last run of the night, I capped the cutout & decided to see just how bad the FMs are. To my surprise I ran a 105.17!!

Humm, just how bad is the FM???? Are some of you guys just repeating what you’ve read on the internet about FMs poor performance? I realize other guys have tried the same kind of test before and have gotten poor results, and I’m not bunking your experience. I’m just wondering if FM’s poor performance reputation is just based on too little information.

<small>[ September 08, 2002, 03:48 PM: Message edited by: nuzee ]</small>

nthnwbr

I think most of the bad reputation, is because other companies make "straight through" design mufflers, that are less restrictive. But, IMO none of them sound near as good as the FM. I don't know if there is actually any flow tests that have been done, so most guys just go by what they've heard.

Damian

iTrader: (89)

The "American thunder" and other similar designed mufflers do not flow very well. Their poor design is made for noise, and not power.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">I don't know if there is actually any flow tests that have been done, so most guys just go by what they've heard.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I have personally seen cars make more power on the dyno when ditching a FM catback for a similar priced catback. I also watched a buddy lose 18 rwhp through a Flowmaster catback, compared to his cutout on a cammed car.

Josh

sited12

Im not a fan simply because thats what all the six cyl. cars get. Its kind of like not getting a wing for me. All the none performance cars have them. I do have to admit they make sixes sound likes eights. I have been waiting for them to come out with a system for the new Monte Carlos so i can put one on my girlfriends SS.

TanRchy

Dont be a Flowmaster hater. They make very good mufflers and while they may not flow well for our cars they do for others. On trucks IMO there is no better sounding muffler.

Narcosynthesis

They sounded great on my mustang. Dont hate, congratulate.

I still have a loudmouth on my SS though.

CHRISPY

Did you know that the 2.5 inch systems from dynomax flow better than the three inch flowmaster systems?
There isnt any comparision at all really.
If you are near stock then a 3 inch race flowmaster will be adequate but when you are running in the 118-124mph range in the 1/4 the flowmaster is done over ~20RWHP versus a dynomax Ultraflo single in/out 3 inch muffler.
Chris

GREEN GOBLIN

I agree, Flowmaster's sound great, but for the Camaros and Trans Am's they just don't produce the desired horsepower we all look for.

1CAMWNDR

iTrader: (21)

With all that has been said about the Flowmaster not working for Camaros and Firebirds; I think it can be safely said that Flowmaster's cross flow 80 series muffler sucks.
I for one think that ALL cross flow style mufflers leave a lot to be desired.
If you want Flowmasters and good HP from them; better step up to a dual system and then pick your mufflers. I personally want the DeltaForce 10 series mufflers on mine. 2.5" tube diameter. Muffler case is only 6" or so long <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> .

DinoZ

iTrader: (5)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by nuzee:
<strong> I was running a very consistent 13.2s@105.6-7 mph. Last run of the night, I capped the cutout & decided to see just how bad the FMs are. To my surprise I ran a 105.17!!
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You just kind of showed yourself how performance inhibiting they are... you were running @ 105.6 to 105.7 and then capped your C/O and dropped to a 105.1! You dropped a half mph, which doesn't seem like alot, but it's still a decrease in performance.

LS1derfull

Nuzee, i tested American Thunder vs open y-pipe with stock cat back, and Flowmaster ran same mph as y pipe removed. This info is concrete to me and no opinions on here are going to change my results or opinion. Flowmaster 2 chamber makes great sound and power with cam and headed car with no headers or ypipe done to it. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

PewterZ

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Viserys:
<strong>They sounded great on my mustang.

I still have a loudmouth on my SS though.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yep....They sound wonderful on mustangs...I'm just not a big fan of the FM catback though....

nuzee

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DinoZ:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by nuzee:
<strong> I was running a very consistent 13.2s@105.6-7 mph. Last run of the night, I capped the cutout & decided to see just how bad the FMs are. To my surprise I ran a 105.17!!
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You just kind of showed yourself how performance inhibiting they are... you were running @ 105.6 to 105.7 and then capped your C/O and dropped to a 105.1! You dropped a half mph, which doesn't seem like alot, but it's still a decrease in performance.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">After reading posts like "FMs perform equal to or worst than stock system", I was expecting at least a 1 mph decrease. My stock system showed approx 1.5 mph decrease. What does a half mph equate to in horsepower??

LS1derfull

About 5 hp, not bad IMO(see my post above) <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

2000silverbullet

iTrader: (5)

I think flowmasters are great. Some of you talk of performance and restiction > well everyone says there system is better.... <img border="0" alt="[Fluffy]" title="" src="graemlins/fluffy.gif" /> > a cat back system is just a small piece of a large puzzle. Flowmasters sound great on my supercharged TA! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> I wanted a crisp deep sound and thats what I got. Next time someone tells you that flowmasters have a bad reputation > they are wrong! Thats a fact! <img border="0" alt="[guns]" title="" src="graemlins/gr_guns.gif" />

gator's 99TA

iTrader: (2)

you all are missed the boat of mph as a function of the Density Altitude. unless the weather was exactly the same (never) then you can not compare the results. DA changes in a matter of hours.

go with the dyno results and if possible do it within a short period of time. mph can change due to weather, traction, driver shift points, etc.

also, look to the actual flowrates in cfm. they tell the story as well. compared to a free flowing dynomax (ZERO restriction) FM will not compare with their 30 year old delta flow system chambers and baffles).

DONAIMIAN

iTrader: (18)

personally i think its the fact that its a cross flow design, if FM made a system to the F-bodies similar to the mustangs (straight in and out) it would make more power. but i think its the fact that FM hasnt masterd the design and the technology to develop a high flowing cross flow muffler <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

nthnwbr

Don't blame the crossflow muffler's inefficiency on Flowmaster, the credit for that brain-fart belongs to GM. <img src="http://forums.off-topic.net/images/smilies/pat.gif" alt=" - " />

35th SS

iTrader: (2)

hey nuzee was that you running side by side with a red z06 conversion convertible at the track?nice run. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

mgreen

Do yourself a favor.

Go to www.summitracing.com and buy the Round Ultra-flo welded muffler by Dynomax.

3" in and out, no curves/turns.
The inside is actually ~3.5".

Granted, you'll only have one tip, but it'll flow like a straight pipe, but be quieter.

Just cut your flowmaster system where it connects at the muffler and weld in this new muffler.

Dynomax part number 17223

<img src="http://store.summitracing.com/partdetail.asp?part=15746&view=257#largerimage" alt=" - " />

No matter WHAT all the FM lovers say, they'll never make as much hp as a straight through muffler.