I went to the track tonight. I went because I ditched my Magnaflow cat-back for a Flowmaster cat-back. I did the swap for the sond quality more than performance (yep, I KNOW the Magnaflow supposedly flows way better), but I wanted to see how much power/ time I lost.

Well, bottom line, my 1/4 mile times improved .1 and my MPH was up 5 miles per hour on average all evening !! So, how can the Flowmaster "suck so bad" but give such a gain at the track? The environment is not a factor in this either. I live in Hawaii and the temp/ humidity changes mabye 10 degrees/ percent year-round. If anything, it was more humid tonight than the last time I went to the track. Also, I did go to the same racetrack and used the same launch techniques as previously.

I guess this post is more a question than anything. I read a lot from here, LS1.com, and camaroZ28.com that the "Blowmaster" sucks in flow and performance, except for the sound department. Well, my track result tonight do not support this. 1/4 mile MPH is a main measure of HP....and this DEFINETLY went up.

Schantin
2002 Camaro Z28 M6

 

and i can show you a post where a guy ran with the flowmaster and then swapped in another catback and gained mph and knocked some time of his e.t.

 

is this really that difficult to undersatnd?

magnaflow borla and straight through mufflers alike... air goes ----- schwoop...right on through...

flowdisaster..flowcrapster...dammit...Flowmaster air goes __/\/\___ when air starts boucning around, its going to slow down flow...Flowmaster is the cowbell of mufflers....Loud as ****, and just like a cow do you really need something so loud on it so u know its coming when its moving slower than everything else?

considering you have a M6 im gonna take a guess that maybe since the last time you were at the track you improved your driving skills. have you compared your 60 foot times from previous track runs and these new ones?

could have a fluke system...still for me 1 out of the 100 people i've heard complain about it i can't say id ever recommend it to anyone.

 

I wrote the post about picking up MPH with the magnaflow.The DA/humidity/temp was drastically worse.The track sucked and I worsened my 60' from 1.90/1.93 to 1.99/2.05 and still broke into the 12's.I may take this weekend to get some more runs,the weather is cooler and may duplicate the flowmaster conditions.I can say with LTs and !cats the flowmaster 80 is really terrible sounding.The magnaflow/18" bullet combo is shear music.

 

That's true of any exhaust.

 

I'd say you must be a very inconsistent driver, or your car is very inconsistent. 0.1 seconds is approximately 10 rwhp gain. 5 mph trap speed is approximately 60 rwhp gain.

I highly doubt you picked up anything from the muffler swap, your results don't even match eachother. You should have ran either .1 faster and 1 mph faster, or 0.5 faster and 5 mph faster if your car is consistent.

A Flowmaster muffler was the very first mod I did when these LS1s first came out. I thought the car was too quiet, so I put the muffler in. 0 gains on the track, 0 gains on the Dynojet. All I gained was sound. Needless to say, I ditched that muffler pretty quick.

 

Well, I didn't expect praise and support for this post . As for consistency, I keep it pretty consistent. Launches are at 1500RPM and the 60' has hovered between 2.19 and 2.26. I know this alone could result for the .1sec improvement, but not the total MPH gain. I guess DA could affect a change allowing for the MPH ,or heck, even the track clock could be registering a bit different.

Bottom line is that I lost nothing going from a Magnaflow cat-back to a Flowmaster cat-back. Maybe I'm an anomoly, but that seems to be the case.

Also, as a side note, no crossflow muffler will give "great" performance. The loudmouth does so well because it's a straight through resonator. Ideally, if maximum flow is such an issue, people should run straight through mufflers with only one tailpipe, or true duals. This is because the airflow has to split in the crossflow muffler on the two exits. This creates turbulence, which reduces overall performance. (I'm not pulling this out of my keister either ) I don't see many single tailpipe setups on Z's. So, even if sound is not a great issue for others, it seems appearance is.

Look at another point. When dealing with cylinder heads people are always warned that total flow is not the big pictue. Lift, etc are all factors and effect this number as well as total performance. So why is exhaust treated differently. I can tell from experience that the car needs some backpressure to maintain torque. I had a 97 and removed the cats when I installed LT headers. Phenomenal gain on the top, but I lost a lot of low-end torque. With the Flowmaster cat-back exhaust, I'm running 3" throughout. The Magnaflow had 2.5" outlets and tighter pipe bends. The Magnaflow muffler may flow a lot more, but what's the BIG picture?

This comes back to my origonal post a week ago. Exhaust is subjective and personal thing. I personally like some volume, others want maximum flow. Just because the Flowmaster is cheap, loud, and readily available, doen't mean it's worthless. I think it's reputation is due in part that "Flowmaster" has been associated with mullet wearing rednecks driving old 5.0's and 3rd Gen F-bodies who live in metal twinkies (Which I am neither of )

Schantin
2002 Camaro Z28 M6

 

you launch at 1500 rpms?

my magnaflow catback is 3" all the way back btw

 

Yes. With 18x9.5 rims and Kumho tires, I get horrid 60' times with a higher RPM launch. I can keep it in the 2.1-2.2 range with the "soft" launch. It goes to 2.4-2.5 above 2,000RPM

On the flip side, the car handles awsome on a closed track. That's really what she's been set up for

Schantin
2002 Camaro Z28 M6

 

Pretty good instruction there but the "big picture" is a 2.1-2.5 60' is pretty dismal and spinning the tires WILL increase most cars MPH at the 12-13 second area,I've seen it many times myself.Just be satisfied with the muffler but don't try to reason its the best choice by telling me my trailer and haircut make me a redneck.
heres me before w/flowmaster 2 runs with 68* weather and 2100 DA
1.93 1.90
5.49 5.51
8.46 8.44
85.13 84.91
10.96 19.95
13.04 13.03
108.7 108.9
1 week later after magnaflow 2 runs with 89* weather and 3600 DA HUMID
1.94 1.93
5.53 5.51
8.43 8.42
84.74 84.97
10.91 10.92
12.98 13.00
111.32 110.93
pretty consistant runs and in far worse weather.I made 2 other runs and were 13.01 and 13.03 and I can't 60' either but I'm still working on a 12 bolt fund. flowmaster

 

Bottom line: It's a fluke. There are dyno #'s and track times and flow tests that prove Flowmaster sucks.

EDIT: Found some numbers

Stock muffler- ~200 cfm
Flow 80 series- ~360 cfm
Hooker- ~900 cfm
Magnaflow- ~1100 cfm
Loudmouth- ~2200 cfm

 

A straight through 3 inch pipe only flows ~1000cfm at ~20 inches.

what test pressure where you using for the test?

 

I found those in another post, so I dont know specifics. I guess I could try to find out?

 

Such a misnomer...in laymens terms and in a nutshell, the torque curve has been moved farther up the rpm band. Backpressure IS NOT YOUR FRIEND. There are plenty of articles on the web now so I won't elaborate here.

This says it all right here

 

Anyone know what a GMMG flows??? It looks like it's pretty much a straight through design just turned??

I've already got mine and love it but was just curious.

 

Schantin
First, welcome to the board!
Good to see another Hawaii guy posting. FYI, I run Flowmaster too (got it free from another F-body guy). I also have a cutout that I open at the track. I've done cutout open vs. closed a few times and have seen a consistent near 1 mph improvement with the cutout open.

This is my take on the flowmaster.... For stock or near stock power leveled Z28s or Trans Ams, the flowmasters provide an improvement. Some SSs or WS6s come with better stock exhausts so the flowmasters don't show much improvement, if any. Once you start modifying and make more power, the flowmasters become restrictive.

Now for the reason you saw such a huge gain in mph.... Maybe the Magnaflow caused your air/fuel mixture to go too rich or lean. Then the flowmaster caused it to go to an optimum air/fuel ratio. ....or.... that Magnaflow weighs 500 lbs.

 

You are 100% correct with this statement. On a car that spends most of it's life on the street and not the track, it is not benificial to have the torque curve in the upper RPM band. Rarely does my car exceed 3500RPM when normally driving.

Schantin
2002 Camaro Z28 M6

 

Yeah, I would agree with ya'. Glad I'm not the only other person in HI with a Camaro!! Unlike H1 potholes and Honda owners, we're a rare breed !

Schantin
2002 Camaro Z28 M6

 

Ok, yes baffles are counter intuitive to flow. You think something is in the way thus it must be impeding exhaust flow, well this is not always true. Here is why. (some guy a lot smarter then me wrote this): An old hot rodder's tale is that headers produce more power by reducing backpressure and by the long individual runners preventing the exhaust blast from one cylinder from blowing into the next cylinder, contaminating the charge on overlap. While this is partially true it is not the primary reason why headers produce more power than a stock manifold.

Headers make more power by primarily using resonance tuning to create a low-pressure, reflected wave rarefaction pulse during the overlap period. (The overlap period, remember, is between the end of the exhaust stroke and the beginning of the intake stroke. At this time, both the intake and exhaust valves are open at the same time for a few degrees of crankshaft rotation.) Engine designers take advantage of this overlap period to help the engine breathe better.

A well-designed header can use ACOUSTIC energy to maintain low pressure near the exhaust valve during the overlap period. (ok im back) This basically creates a vacuum in the manifold and thus more exhaust flow. (im paraphrasing trust me you want me to)

Flowmaster mufflers work in much the same way, using acoustic energy to pull exhaust gasses out. Thats why the baffles are there. The delta flow mufflers are a perfect example of this. So in reality it flows a lot more then you think it does.

Want to know more? copy this link:

http://www.sportcompactcarweb.com/te...scc_ssbbpart2/

its a compact car site but trust me the article is about intake and exhaust flow which still holds true in good ol muscle. So learn a thing or two

 

Whenever a speed part is advertised as tuned, I am leary. A tuned exhaust is just that, tuned for a specific application.

At what pulse frequency (RPM) is the flowmaster tuned? 3000 to 7000 RPM? That would truely be an amazing range.