flowmaster mufflers

Enough with all the suppositions. I had 2 chambered Flows welded into my '98 headswapped GT and lost 7 hp over stock muffs. Dyno-tested. I could feel it SOTP as soon as I left the muffler shop too. So, no matter whether they flow better or worse than stock, I lost real HP. Had to buy a Vette just to get it back.
 
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bierbelly said:
Enough with all the suppositions. I had 2 chambered Flows welded into my '98 headswapped GT and lost 7 hp over stock muffs. Dyno-tested. I could feel it SOTP as soon as I left the muffler shop too. So, no matter whether they flow better or worse than stock, I lost real HP. Had to buy a Vette just to get it back.
There is no way you lost 7rwhp from flowmasters. There was probably a difference in conditions or something. The tornado is also DYNO PROVEN to increase horsepower.
 
New22003, I am sorry I have enough money to buy Borlas and to have a second car to drive to work and else where. And you are just as dumb as anyone slse who says a Flowmaster is any better than a newer stock Mustang Muffler.

You think the fact that these mufflers suck would much more obvious to people.
 
Ryan02Stang said:
There is no way you lost 7rwhp from flowmasters. There was probably a difference in conditions or something. The tornado is also DYNO PROVEN to increase horsepower.
There are many conditions to consider. I've seen 10 horsepower variations from one pull to the next within a 5 min period, no mods changed.
 
It is very easy to see +/- HP within the same group of dyno pulls. Thats why most companies say there product adds -blank- HP. They simply record the best dyno pull and compare it to the lowest and call it a gain.
 
bierbelly said:
Think what you want, but I noticed the reduction in low end torque immediately after the swap.

Well if you lost LOW end tork, then that usually means that you increased flow.A restricted exhaust gives good lowend, but sucks on top end...a good flowing exhaust is basically oppisite.I have 3 chaber flows on my 66 and it doesnt have hardly any low end power LOL(but man it comes in HARD past 3K or so), and the exhaust will hit you like 10 feet back when you rev it.If you look inside of a flowmaster, you will see that it is not that restrictive.Anyone have a spare stock muffler laying around after a exhaust swap?If so, saw it in half (length ways, and straight up and down if you can) and post pics of it...then we can see exactly how it is designed and how restrictive it really is compared to the flows.
 
Here's my experience with Flows. Granted this is on a built '65 with a 302 and not a 4.6. But going from stock to Blue Flame glasspacks helped. But seat of the pants change going from the glasspacks to 50 series Deltaflows was really noticable; power, torque and gas mileage. Adding a balance "cross" tube is even more noticeable. I am skeptical that someone might have lost torque and increased backpressure with flows. But it is possible they got some bad ones or used small diameter pipes or had a less than stellar shop install them. Haven't tried them on the '01 yet. Maybe some day. They sound great.
 
Rio96 said:
Could some care to offer an explanation:
Why is backpressure EVER helpful to torque?
(at low RPM, or whatever)


There are two important aspects of exhaust:

1. Exhaust gas VELOCITY
2. Resistance to flow (backpressure, if you will.)

Sometimes if you increase the resistance to flow a little (narrower pipe for example) the velocity of the gases will increase.

You want high gas velocity because it will suck the exhaust gas from the compression chamber (called scavenging (SP?)).

You want low backpressure so that the resistance to flow of exhaust gasses is low. If the backpressure is too low, you have lost too much of the valuable velocity.

You trade velocity for backpressure, usually, so you need a proper balance. This is why there are no 3" diameter or larger exhaust parts for non poweradder mustangs. It would slow the velocity and kill the scavenging (SP?) effect in the combustion chamber. You don't see 2" or smaller, because it would be too restrictive to the flow of exhaust gasses.

Just to complicate things, the proper balance is different for different RPMs the enging is turning. You can have an exhaust that is TUNED to give a perfect combination at the High end, but this combo will not have the sufficient velocity at partial throttle to give good scavenging at low RPM (low volume of exhaust gasses). This causes a loss of low end power.

The exhaust system of a stock mustang is so restrictive that there are mods you can do that give accross the board gains, up to a cirtain point. Then, as you get the last little bit out of the exhaust system, you need to start making compromises as to where the system is going to be tuned for.

Hope this helps.
 
I think you're full of it. Exhaust gases are positive pressure, not vaccum (sucking). There's no sucking involved in the exhaust--nothing sucks the exhaust out of your motor. It's pushed out by expansion.
 
huesmann said:
I think you're full of it. Exhaust gases are positive pressure, not vaccum (sucking). There's no sucking involved in the exhaust--nothing sucks the exhaust out of your motor. It's pushed out by expansion.

I'm not sure what it's called, but the effect of a larger opening into a smaller opening creates suction. Like in the venturii of a carb or your the way your toilet flushes.