Flowmasters? Whats the deal?

[dr_frankenstein]

I keep hearing this myth that Flowmasters are no good for a turbo,
but nobody can tell me why or show any evidence. I want to know what the deal is with these! Are they bad or what? and why?

A.j.

 

[slow305]

From what I understand, the baffles restrict the spooling of the turbo because of the inherent back pressure. While this is good for a N/A car because it helps with low (engine) speed torque, the turbo delivers plenty of back pressure on it's own (pre-turbo). After the turbo you want zero restriction.

On a personal note, the most advantageous upgrade I have done to my Buick so far was dump the Flowmaster the previous owner had in and get the Hooker exhaust. At around $370, it is well worth it.

 

[blackmonte]

Well I can tell you first hand I know a guy on here has 40 series on his GN with a 70GTQ and would not be able to say he has lost any performance and I think they sound great, the reason they say the baffles inside hinder flow unlike a straight through muffler they go around the baffles making turns , I myself would like to see it on the Dyno. People get stuck in there ways because everyone uses this or that muffler on a turbo car, I say put on there what you like, I have magnaflows on mine now but I am also thinking about Flowmasters.

 

[notacarlo]

The drone the flowmasters deliver in these cars will make you want to strangle puppies.

 

[1of1547]

The drone the flowmasters deliver in these cars will make you want to strangle puppies.

You are right about that one. I had a single 3" two chamber mine that would drive me nuts around 2300-2500 rpms. I know mine would pick up 1.5#s when I would uncap the dump vs closed exhaust. But it did sound good!!!

 

[TurboDave]

I keep hearing this myth that Flowmasters are no good for a turbo,
but nobody can tell me why or show any evidence. I want to know what the deal is with these! Are they bad or what? and why?

A.j.

It's no myth. If you don't take my word for it, then ANYBODY with more than a basic understanding of turbo technology can tell you that any... Let me repeat ANY backpressure downstream of the turbocharger is detrimental to it's efficiency.

You're still stuck in the N/A (normally aspirated) world and the exhaust theories that work in their world are not applicable to the turbo world.

The perfect solution would be nothing more than a short piece of pipe off the turbine housing, just enough to get the exhaust away from buring anything. This of course insn't practical (except in full race situations).
Some exhaust system is needed for practicality. The next best thing is muffs that are straight thru with only perforations, nothing protruding into the exhaust stream. Even the most ideally desingned system with bends is going to produce some backpressure, any bend will produce some.

That's the reason the flowmasters are not ideal for turbo applications. They may work well in N/A applications but that's about it. They just produce too much backpressure to be of any benifit at all.

It's easy enough, any downstream backpressure is bad. Buy the parts accordingly.

 

[notacarlo]

I got 3" straight pipes all the way back and they sound better than with mufflers. It's still a restriction, but for the street it works well.

 

[dr_frankenstein]

It's no myth. If you don't take my word for it, then ANYBODY with more than a basic understanding of turbo technology can tell you that any... Let me repeat ANY backpressure downstream of the turbocharger is detrimental to it's efficiency.

You're still stuck in the N/A (normally aspirated) world and the exhaust theories that work in their world are not applicable to the turbo world.

The perfect solution would be nothing more than a short piece of pipe off the turbine housing, just enough to get the exhaust away from buring anything. This of course insn't practical (except in full race situations).
Some exhaust system is needed for practicality. The next best thing is muffs that are straight thru with only perforations, nothing protruding into the exhaust stream. Even the most ideally desingned system with bends is going to produce some backpressure, any bend will produce some.

That's the reason the flowmasters are not ideal for turbo applications. They may work well in N/A applications but that's about it. They just produce too much backpressure to be of any benifit at all.

It's easy enough, any downstream backpressure is bad. Buy the parts accordingly.

But Chief, is there any data to show the amount that they increase back pressure? Not to say your wrong, but I was looking for hard numbers..... to see what i have to deal with.

Drone is of no issue to me, I have an open pipe(s) now - but my neighbors are starting to get tired of my 5 am 10 minute warmup. I like the sound of the flowmasters, as there a more deep toned kinda sound.

It just seems like a 3 inch muffler(s) with a few turns and baffles shouldnt cause that much back pressure....... I mean some is OK for me, Im not after every last drop of HP. However, I am in a non stock application and my mufflers are behind the axle (mini truck) could placement affect the back pressure problem?

AT2 (AW) A.j.

 

[slow305]

That's where mine was, behind the axle I mean. Two pipes in, two out of one muffler. I think the one I had was a little dated too (read: old and rusty), plus it might have had some cat pieces in it too.

That's Senior Chief..

ABH3

 

[TurboDave]

But Chief, is there any data to show the amount that they increase back pressure? Not to say your wrong, but I was looking for hard numbers..... to see what i have to deal with.

Drone is of no issue to me, I have an open pipe(s) now - but my neighbors are starting to get tired of my 5 am 10 minute warmup. I like the sound of the flowmasters, as there a more deep toned kinda sound.

It just seems like a 3 inch muffler(s) with a few turns and baffles shouldnt cause that much back pressure....... I mean some is OK for me, Im not after every last drop of HP. However, I am in a non stock application and my mufflers are behind the axle (mini truck) could placement affect the back pressure problem?

AT2 (AW) A.j.

I have no empirical data in front of me, although I've seen the numbers (back-pressure) posted somewhere years ago.
If you're not all that concerned with the loss in HP, and are more concerned with how is sounds, then trying to find data would be pointless anyway.

Those of us that are constant tweekers looking for every drop of safe HP that can be generated are more concerned with things like this.

 

[83ttypecooled]

Hi,
My TTA has a Flowmaster.So does The Turbo Cherokee. Personally, after long drives in both vehicles,I can tell you that I HATE that drone. It's at cruising speed, approximately 2300 rpm. My Regal,however, has a Hooker cat back system,no annoyance,but it sounds authoritative,so to speak.

 

[1of1547]

Here is a link that I saved years ago Muffler Flow Tests .

 

[cchilly]

When I bought my car it had a 3" single shot with a flowmaster that dumped right before the rear tires. The drone was pretty bad, so I ended up putting on a Borla XR-1 muffler that I had lying around. To be honest, I didn't really notice any performance difference between the 2 mufflers. My car is basically stock though and running about 15 psi.

I think the Borla does sound better with less drone.

Chris

 

[QuickBuick87]

Wow....after looking at that chart, i'm gonna chuck the Flowmasters currently on the GN. They came with the car, and I just didn't see a reason to replace them......until now. Thanks for the link!!

Ken

 

[novaderrik]

when i put the Flowmaster stock replacement crossflow muffler on my car, it made it run better. until i got that kit, i just had the stock pipes ending right over the rear axle where the stock muffler hooked up to it- i had cut off the stock muffler becasue it was all rusted out and blown apart and drove it like that for a couple of months.
i don't have any sort of a drone, and it sounds about the same as it did with the open pipes. but i did notice right away that it runs better and is more responsisive with the Flowmaster than without.

 

[sabersaw30]

But Chief, is there any data to show the amount that they increase back pressure? Not to say your wrong, but I was looking for hard numbers..... to see what i have to deal with.

Drone is of no issue to me, I have an open pipe(s) now - but my neighbors are starting to get tired of my 5 am 10 minute warmup. I like the sound of the flowmasters, as there a more deep toned kinda sound.

It just seems like a 3 inch muffler(s) with a few turns and baffles shouldnt cause that much back pressure....... I mean some is OK for me, Im not after every last drop of HP. However, I am in a non stock application and my mufflers are behind the axle (mini truck) could placement affect the back pressure problem?

AT2 (AW) A.j.

Sounds like to me you want to run them regardless of flow.If you like the way they sound run them you got to drive the car nobody else does.You might get beat alot (only kidding).Run what you want that is the only way you will be happy.

 

[SPOOLN]

I repalced the hooker mufflers with two flowmaster deltaflows and seen no difference with it dumped and capped up. That was running between 20-22 # boost.
On my other TR i repalced the stock crossflow with the 2 1/4 force 2 kit and seen no difference except that the flowmaster crossflow is quieter then the stock crossflow.

 

[dr_frankenstein]

Sounds like to me you want to run them regardless of flow.If you like the way they sound run them you got to drive the car nobody else does.You might get beat alot (only kidding).Run what you want that is the only way you will be happy.

well not necessarily, I do want every bit of horsepower that counts- but if were only talking about a 5 or 10 HP difference between one muffler and another than I dont see any point in getting a different set. I have a brand new set of delta force flowmasters available to use from a different project..... why buy another set?

Im only asking, because I have heard tons of rumors that the flowmasters DRASTICLY reduced HP.... but if im going to give up a few ponys then its a moot point.

not trying to start a fire, just trying to find the truth.

Thanks to all for the replys.

A.j.

 

[BlackMetal]

I don't think a lot of these little things people worry about really make a difference until you're running 10s down the track and are worried about every 10th of a second you can get. Flowmasters are not going to suffocate a street car.

 

[TurboBuRick]

I don't think a lot of these little things people worry about really make a difference until you're running 10s down the track and are worried about every 10th of a second you can get. Flowmasters are not going to suffocate a street car.

I agree 100%