vetteguy75

I just finished watch 2 Guys Garage and they were talking about exhaust systems. One of the things they mentioned was how to get max hp. One way to do that is to get the exhaust out of the cylinder as fast as you can. Heartthrob or Cherry Bomb exhaust has a flow-thru system which allows for min backpressure thus getting the exhaust out of the cylinder faster. That being said, how does FlowMasters work? With the way their mufflers are designed, there seems like there would be a lot of back pressure. I can see how a glass pack or flow-thru muffler would do the job....so how does a FlowMaster work? I have the 40 Series on my Vette and love it....this is more of a curiosity question....

73jst4fun

I have the 50 series which sound great. Their design allows for more volume and scavanging of the hot gases so the back pressure is minimal, the 50's have I believe three chambers and yours have two, which make your a little louder. I would go to their website for a more technical answer than mine.....hope this helps...

LiveandLetDrive

Why would they have more back pressure? Are you talking about a Flowmaster that has something in it besides a couple baffles? The perforated tubes in a glass-pack muffler are moving a significant amount of gas through those holes or else they wouldn't be any quieter than straight pipes. The gas that goes into the fiberglass section is going to slow down greatly and when it pops back into the tube, will do a lot to disrupt the flow. The Flowmasters on the other hand will have some turbulence of course but not nearly as much. There may be a baffle right "in the way" of the exhaust flow but on the whole it will flow through in a fairly cohesive way. As far as the acoustics of removing the sound, I'm less up on that. Their website probably has some technical stuff amongst the marketing spin.

I've had the 50's and now have the 40's. Granted there's a 250HP difference between the engines but the 40's are quite loud (in a good way ), the 50 Deltaflows had a great sound on my 350 with ~270HP.

jae1971

Have the flowmasters on my '71, They sure sound good if nothing else.They do flow much better than any stock muffler, can't see putting glasspacs on a vette.

7T1vette

Just select the correct pipe and muffler size for your engine's performance. Flowmasters [or any other decent brand of muffler] will not overly restrict exhaust flow, if they are properly sized. The "2 Guys Garage" show is just selling "stuff" for their sponsors; disregard any recommendations that they make on the show. The "How To" portion of the show is fine.

73jst4fun

"sound" advice, no pun intended.....

Billysvette

Flowmasters dont flow that great,sorry if its a let down,but they do sound good and i do like the sound of them,but compared to staight through designs,flowmaster doesnt compare. there has been alot a research on here about this subject,do a search.also on one study i read on here was that between all mufflers there was like only 5 to 10 hp difference between them.I wouldnt worry about it.

Bugman Jeff

What he said. Despite the name, they are not in fact the masters of flow. In exhaust flow comparison tests(measures in pressure drop across the muffler or CFM), Flowmasters are generally towards the bottom of the list. They just have a very good marketing campaign.

jordan89

I still love the way those Flowmaster mufflers sound. I have some Magnaflows that are going on my '78 Z28, and I'm also planning on going the same route with the Vette. There's nothing wrong with Flowmaster mufflers, you just have to choose the right ones that are right for you.

eagle275

so, who has the best muffler? Just curious.

Billysvette

Any straight through muffler will flow good.take your pick.

jordan89

...Roger...

Huh , what did you say ??? The 82 I just bought has new Flowmasters and they will wake the dead. I absolutely hate the way they sound except at idle.

ajrothm

Hooker Aerochamber

Try these....they have a "similiar" sound to flowmasters....but flow like a straight thru.... They don't have that glassy, crackely, raspy sound that all of the straight thru/glass packed mufflers have...(ie. Magnas, Ultraflows, etc...)












Just throwing that out there for someone wanting a good sound and minimal power loss...

Billysvette

It may not be pleasing to you ,but those people that hear you go by sure have a smile on their faces Flowmasters drone bad inside the car,but they do sound good at idle and going by and down the road
Personally, i dont run them, too much drone.

eagle275

7T3C3TTZ07

Many have probably seen this:
Muffler, Air Flow, DB at 3500 RPM
Hooker Aero 73% 98
Flowmaster 40 59% 100
Flowmaster 50 53% 98
Dynomax Ultra 99% 91
Dynomax Turbo14" 70% 93
Dynomax Turbo20" 70% 88
I can't determine the authenticity.

Bugman Jeff

From elseware on the forum, but worth reposting. Flow of various mufflers, measured in CFM:

OEM..................................... ........................................ ...225
Gibson SuperFlow 788200.................................. ............311
TTS Bullet Cat Converter............................... ..................324
Flowmaster 40 series 42540................................... .......352
Flowmaster 50 Series.................................. ...................362
Flowmaster 40 series 43040................................... .......392
Dynomax Super Turbo................................... .................410
Flowmaster 62631................................... .......................435
Carsound Cat Converter............................... ..................436
FLP Cat Converter............................... ............................440
Edelbrock Victor 5535.................................... ..................562
Flowmaster 40 series 435409.................................. ........576
Edelbrock RPM series 5511.................................... ..........579
Flowmaster Delta Force Racing 54040-10........................634
Edelbrock 304 series 5560.................................... ...........640
Edelbrock Gen App 5505.................................... ..............708
Dynomax Race Magnum Welded 17216...........................711
Borla XR-1 40600................................... ..........................836
Borla XR-1 40615................................... ..........................854
Dynomax UltraFlow SS 17263................................... .......1000
Dynomax Race Magnum Welded 17218...........................1000
Borla XR-1 40575................................... ..........................1100
Dynomax UltraFlow............................... ...........................1133
Edelbrock Victor 5537.................................... ..................1400
Borla XR-1 40450................................... ..........................1400
Borla XR-1 40741................................... ..........................1450
Dynomax UltraFlow SS 17296, 17268..............................2200
Dynomax Race Magnum Welded 17220, 17224...............2200
Dynomax Race Magnum Welded 17225...........................2600

The formula for required exhaust flow is: horsepower times 2.2. Pretty simple eh?

So if your car makes 400 hp, you will need a total of 880 cfm muffler capacity for an unrestrictive exhaust system. So for dual exhaust, you would need mufflers that flow 440 cfm.

For reference, a 2.5 inch diameter pipe flows ~500 cfm. Adding non-mandrel bends will lessen that amount.

Billysvette

Why is dynomax ultra flow mufflers different in cfm,one is stainless steel and the other is regular steel,same muffler but made of different material,should be the same.

Bugman Jeff

Note that the part numbers (where listed) are different. Different designs and diameters of mufflers. Has nothing to do with the material, just the shape/size of the muffler. For instance, the 17263 UltraFlow is a 2 1/2" pipe with an oval case, the 17296 UltraFlow is 3" with a round case