Flowmaster mufflers dyno data?

[Andrew Robertson]

Hi All,

have just finished the headers and exhaust system on my car. Used PipeMax program for design guidance after feeding in the detailed dyno info I have for the 434 SBC, and have 1 7/8 primary about 32 long into 3 inch collector 18 inches long and using the 40 series flowmaster chambered muffler as the assumed end point in the system because of its volume.

I've come across a school of thought on another forum that seems to be down on flowmaster mufflers, and in particular seems to regard them as distinctly inferior to Magnaflow straight through mufflers. These are a perforated core (not punched in like cheap glasspacks) with stainless steel wool packing - not really a fair comparison and presumably very loud.

When I pressed them for data that backed up the claim that flowmasters cost power I got mostly second hand anecdotes, although I imagine they are down a bit on a straight through design. I'm trying to find out if they are up there with the best chambered muffler (and I'm planning to fit a pressure transducer into the collectors and log system back-pressure at WOT when I test) but for now does anyone have hard dyno data they could share?

Cheers, Andrew

 

[Dom]

ive been told flowmaster rob horsepower but magnaflow dont.... baffle design will take horse power anyway as they are slowing the gasses down...what flow are your flowmasters rated at??

 

[Andrew Robertson]

Don't know what they're rated at but I checked the part number again and they are not the traditional 40 series flowmasters, they are #9430119 10 series single chamber race mufflers so will presumably have little in the way of baffling internally.

Cheers, Andrew

 

[Jac Mac]

Andrew, I dont go on published data, dyno numbers or any of that bullshit, but I base all of the mufflers I build for Race cars on the Flowmaster principle simply because its easy for me to fabricate & adapt to different applications as I see fit [ never actually used a 'Flowmaster' as such & have been building these for that long that I might have invented them without realising it], however in doing so I dont think I have never seen a performance loss in any ( That includeds Jet Boats both Sprint & Marathon which are essentially a floating Dyno ), my main reason for building them initially was the need to incorporate the tailpipe length & muffler in a limited space area particularly in heavyweight stock cars & sprint boats when the noise limits were introduced, in some cases we actually picked up RPM/speed in these applications over the previous 'straight' pipes ....

 

[Andrew Robertson]

Andrew, I dont go on published data, dyno numbers or any of that bullshit, but I base all of the mufflers I build for Race cars on the Flowmaster principle simply because its easy for me to fabricate & adapt to different applications as I see fit [ never actually used a 'Flowmaster' as such & have been building these for that long that I might have invented them without realising it], however in doing so I dont think I have never seen a performance loss in any ( That includeds Jet Boats both Sprint & Marathon which are essentially a floating Dyno ), ..

Thanks Jac, that's comforting - I've seen several very nice custom fabricated mufflers using the design adopted by flowmaster. I like the way a chambered muffler can be positioned in a system to tune the collector length too. I think the magnaflow vs flowmaster thing has become somewhat of an urban myth.

Cheers, Andrew