[71 chevy]

just want to know your results. will be testing this next week.

I have these flowmaster 40s on my car 2.5"
I put them on when I had the 327 and noticed no power increase over the glasspacks that came with the car. heck, it felt slower(and sounded worse)

anyhow, I now have them on the 468 and I have this feeling that its costing me a significant amount of power. opened the cutouts for the first time today and the afr was reading 1 point leaner at idle(which is expected) but like 3 points leaner just revving it. this just tells me that the mufflers are SERIOUSLY choking the engine. my rationale for that is that if they didnt impede flow and kill performance that much the afr would not change that much.

anyhow, I'll be testing it next week and I'll be surprised if the open cutouts dont show 20-30 hp over the blowmasters, then I'll be throwing them in the trash shortly thereafter.

 

[FourEightyNine]

Went from 2 1/2" 40series flowmasters dumped at the rear end. To open headers.

Went from 106mph to 110.3mph:yes: in the 1/4mile.

 

[aukai]

Seun I think anything 2.5 will choke the motor. I put 3" exhaust and ultraflos with cutouts ran 11.68 closed and 11.56 open back to back.

 

[curley8788]

just want to know your results. will be testing this next week.

I have these flowmaster 40s on my car 2.5"
I put them on when I had the 327 and noticed no power increase over the glasspacks that came with the car. heck, it felt slower(and sounded worse)

anyhow, I now have them on the 468 and I have this feeling that its costing me a significant amount of power. opened the cutouts for the first time today and the afr was reading 1 point leaner at idle(which is expected) but like 3 points leaner just revving it. this just tells me that the mufflers are SERIOUSLY choking the engine. my rationale for that is that if they didnt impede flow and kill performance that much the afr would not change that much.

anyhow, I'll be testing it next week and I'll be surprised if the open cutouts dont show 20-30 hp over the blowmasters, then I'll be throwing them in the trash shortly thereafter.

this is true, but for the wrong reasons. the AFR is going to read leaner because of the air contamination caused by running open headers. the lean condition doesnt mean the flowmasters are choking it down, it just means there is more air at the sensor as opposed to breathing thru a pipe. that aside, the 2.5 inch system is probably holding it back. i would go 3 inch to allow that motor to exhale.

 

[66 Buick Special]

But you will want Ultraflow or a Magnaflow style mufflers vs the flowmasters.
Magnaflow's have the bonus of using a steel wool type packing vs fiberglass.

 

[71 chevy]

Went from 2 1/2" 40series flowmasters dumped at the rear end. To open headers.

Went from 106mph to 110.3mph:yes: in the 1/4mile.

thats what Im talking about.

aukai, do you think a 400hp motor will benefit from three inch pipes?

 

[WASNTME]

Personally, I think Flowmasters suck....I've never run them, because I'm unconvinced that having all those baffles in the air stream somehow magically increases exhaust velocity. Gimme a perforated core tube muffler that's straight through anyday. If it's too loud, put a Thrush glasspack in front of it, but NOT a louvered core one! I see edelbrock came out with those new EBT or whatever and I think it's silly....I like the Magnaflow style, with the straight through pipe...Edelbrock used to make a muffler I really liked, had a center in/out, but the pipe split in the middle, so you couldn't really see through it, but it flowed wonderfully, and got rid of the ugly sounds....don't know if they still make it or not!

 

[71 chevy]

Personally, I think Flowmasters suck..!

i would agree with that

 

[chevelle01]

Ive got 3" flowmaster 50 series i think (3 chamber) Years ago when the car was running 12.0's or close to it i took the exhaust off which was dumped in front of the axle and had a h pipe. I picked up 1.5tenths and 3 mph, part of that would have been the roughly 60#. I still have the same exhaust which im gonna change before next race, i can only assume its holding me back a lot now. It looks like ultraflos or the magnaflows would be tuff to beat.

 

[aukai]

thats what Im talking about.

aukai, do you think a 400hp motor will benefit from three inch pipes?

2.5 may be enough for 400 HP but it is related to being able to flow. The muffler selection will be more critical with the smaller pipes Flowmasters have a bad rep for flow volume. You may not need 3" but it would be more forgiving with muffler selection. If you RPM the motor at all I would go with 3" that is jmo.

 

[mirage2991]

I have no dyno/ET figures but I went from 3" flowbastards to 3" dynomax ultraflows and felt no SOTP difference. It is quieter inside with the dynomax though, and that's all that matters to me! (screw the neighboors lol). I still like the sound of the Flow's though...so we put one on my GF's truck, just to give it some personality.

 

[Heckeng]

My car ran a 12.64 with cutouts open, and 12.74 through a full 3" flowmaster system. MPH was the same.

 

[bowtie6872]

i would agree with that

ditto..
2 cars one bbc one sbc..
both .drone to no end..
and sound like junk..

 

[Heckeng]

No offense to anyones opinions on mufflers, but I think there is a certain number of people who will always not like what is popular at the time. I am one of those people, and recently wanted to be different so I ditched my older 3" flowmaster system for a new Spintech setup. I listened to them on the internet and loved the sound over my computer speakers. Several hundered dollars later, they are on my car and sound HORRIBLE! I ended up selling them and going back with a new 50 Delta Flowmaster setup and it sounds MUCH better.

This is kind of like Beer opinions. I have friends who say they don't like Budweiser products, they prefer micro-breweries. Well, that is all perspective. Budweiser started as a micro-brewery too so what is the difference? Budweiser is popular. It's always fun to get attention because you are different--just don't be spintech different and sound like crap!

 

[D Stroud]

This is NOT just a matter of opinion.

2.5" 2 Chamber Flowmasters will flow a max. of 435 cfm measured at 20.3" H20
2.5" Dynomax UltraFlows will flow a max. of 1300 cfm measured at 20.3" H20

Do a search on muffler flow and you will see that the Flowmasters are near the bottom of the list when it comes to flow...the UltraFlows will be the top dog!

Not to mention the Ultraflows sound much better

 

[71 chevy]

whats the difference between the round case and oval case ultraflows and why is the oval case about $100 bucks more expensive for each one.

 

[WASNTME]

I would think an oval case would be quieter, as there is more packing, the the thru-pipe is angled in most cases...my parents have Magnaflow polished mufflers on their Roush 97 Cobra Mustang, and it sound AWESOME! I will probably put them on my Chevelle next year when I go through my car.

 

[D Stroud]

whats the difference between the round case and oval case ultraflows and why is the oval case about $100 bucks more expensive for each one.

I believe the round and bullet style UltraFlows are "Race Only" and probably much, much louder.

I believe several guys here are runnin them. Perhaps they'll chime in.

By the way, I gave $71 each for my UltaFlows that are gonna replace the FlowMasters on my Truck. They are 2.5" offset inlet/center out, from Summit. Don't pay anymore than you have too.

 

[smax]

Here is what the bullets sound like

 

[69bu]

This is NOT just a matter of opinion.

2.5" 2 Chamber Flowmasters will flow a max. of 435 cfm measured at 20.3" H20
2.5" Dynomax UltraFlows will flow a max. of 1300 cfm measured at 20.3" H20

Do a search on muffler flow and you will see that the Flowmasters are near the bottom of the list when it comes to flow...the UltraFlows will be the top dog!

Not to mention the Ultraflows sound much better

YouTube - COPO Chevelle

Dwayne,

Do you have a link to the flow numbers?

Thanks