Flowmasters not good for hp?

[skosler]

I keep reading that flowmasters are too restrictive and lose some hp. I just bought some 40 series flowmasters for a good price and now i hear they might hold me back a little. My build is mild ~400 hp and my rpms will be below ~5000. Should I look to swap for somethig better?

stephen

[Danny Cabral]

Originally Posted by skosler

Should I look to swap for something better? Stephen

YES! Use a free flowing muffler.
http://460ford.com/viewtopic.php?t=15606

[skosler]

Well I guess I should have did a little more research. They will have to do for now. Or maybe I'll just go get some 18" glasspacks!!

stephen

[richter69]

Hey Danny are those a chambered or straight through muffler? looking for somthing to replace the Flowmasters on the little hotrod chevy pickup I just put together (not mine, its the wife's bosses' kids truck).

[460Skywalker]

I ran stock replacement mustang type 3 chamber flowmasters for years , the one with the metal heat shield and only a 2.5 biggest size and my car ran just as well with them on. I did run a 3 inch pipe and cut open to 3 inch only in the front. 2.5 out still . Last time i ran it it ran a 6.79 at 101 in the 1/8 at 75 degree afternoon though the mufflers. It ran 110mph on a 100 nx shot {125 Fwhp} though the flows and not spraying out of hole. I thought the 70 lbs of pipe and mufflers it should of picked up something. :cry: I only ran 1/8 and in the quarter they may make a big differance . ED

[Danny Cabral]

Originally Posted by richter69

Hey Danny are those a chambered or straight through muffler? looking for somthing to replace the Flowmasters on the little hotrod chevy pickup I just put together (not mine, its the wife's bosses' kids truck).

The Magnaflows are a straight through (free flowing) muffler:
http://www.magnaflow.com/wideopen/wideopen.asp

[skosler]

Danny: okay, so my flowmasters are not the very best, but since it is a smaller, milder, lower rpm engine it will not hurt as much as they did on your bigger, badder 508, right? I mean you should be "breathing" a lot heavier than I will, so "exhaling" won't be as critical.

[Danny Cabral]

Originally Posted by skosler

Danny: okay, so my flowmasters are not the very best, but since it is a smaller, milder, lower rpm engine it will not hurt as much as they did on your bigger, badder 508, right? I mean you should be "breathing" a lot heavier than I will, so "exhaling" won't be as critical.

You are correct, however, that also means you can't afford to waste any power either.

[skosler]

okay, I found 2 magnaflow 2.5" mufflers that have less than 3000 miles on them. $50 gets them to my door. The issue is that they are not "see through" like ya'll were talikng about. They have a center inlet and offset outlet. A website I found shows that setup with a chamber like design. If that is true then what would be different than a flowmaster?

stephen

[Danny Cabral]

Originally Posted by skosler

The issue is that they are not "see through" like ya'll were talikng about.

Those are the cheaper XL Turbo aluminized steel mufflers; not what you want. Those are not their "Wide Open Performance" series mufflers. Their 'wide open performance' series mufflers are all stainless steel (satin & polished).

[nuclearcobra]

Well i read the same about flowmasters i been using them for years so i took off the flows and put on the dynomax ultra flos bullet 3"in and out 12" long and just like everybody said big diffrence went 10.604 @ 128.38mph verses flowmasters 10.80s @125mph and i think it would have been better than 2 tenths because that day the flairup from 1st to 2nd was crappier than ever.

[feetfirst]

Originally Posted by nuclearcobra

Well i read the same about flowmasters i been using them for years so i took off the flows and put on the dynomax ultra flos bullet 3"in and out 12" long and just like everybody said big diffrence went 10.604 @ 128.38mph verses flowmasters 10.80s @125mph and i think it would have been better than 2 tenths because that day the flairup from 1st to 2nd was crappier than ever.

Have you tried running open header? Im curious to see what the difference would be.........Thanks for testing the ultra flos out, i now know which ones to buy :mrgreen:

[ProStreetFairlane]

X2...Dynomax Ultraflows!
Nick

[nuclearcobra]

Hey FeetFirst i havent tryed open headers against ultra flos but the guys at the track have and they say half a tenth gain at the best with open headers over ultra flows.

[feetfirst]

Originally Posted by nuclearcobra

Hey FeetFirst i havent tryed open headers against ultra flos but the guys at the track have and they say half a tenth gain at the best with open headers over ultra flows.

:wink: