flowmaster JUNK mufflers

bigjoe1 · Post by **bigjoe1** » Fri Apr 18, 2008 6:11 pm

One of my engine customers with a nice 383 Chevy engine has never run the quarter mile times like he should. We have talked about this MANY times. his one eigth mile times were OK, then it would dye the rest of the quarter mile. Just by accident, He removed his mufflers( flowmaster ) His quater mile times improved two to three tenths, and his MPH at the finishline went up FOUR MPH. In all the converdations we have had about why is car would not Mileanhour, I never asked him so he never told me about the flowmaster mufflers.Twice in my recall. I removed the flowmaster mufflers and one picked up 49 HP, and another picked 75 HP. I cant believe they can sell this stuff to everybody.Anyone else seen anything like this ?

JOE SHERMAN RACING ENGINES

Ron Golden · Post by **Ron Golden** » Fri Apr 18, 2008 6:21 pm

Tom Hand wrote a book on building Pontiac's for the street and strip. Great book. He also tested 54 different mufflers on the flow bench, engine stand (with professional noise measurements) and at the drag strip. He found the Flowmasters one of the least desirable mufflers available. Kinda backs up your experience on the dyno.

By the way Joe, did you use to race a black(?) 57 Chevy with a
400 SB?

Ron

mod7 · Post by **mod7** » Fri Apr 18, 2008 7:22 pm

So what mufflers are as quiet as the Flowmasters but don't kill power? I have heard good stuff about spintech and magnaflow. On a budget here....

andyf · Post by **andyf** » Fri Apr 18, 2008 7:23 pm

I know a muffler shop owner who loves those Flowmaster mufflers. Every customer is a two-fer! Once when they install the Flowmasters and then again when they come back to have them removed.

Doug Kennedy · Post by **Doug Kennedy** » Fri Apr 18, 2008 7:34 pm

Kind of like the Junk K&N filters

bigjoe1 · Post by **bigjoe1** » Fri Apr 18, 2008 8:07 pm

The absolute BEST mufflers are the Magnflow. I have been doing ALL my dyno testing with them ever since the Engine Master first contest.
The other day, on a 985 HP BB Chevy, when I took the 4 inch magnaflow mufflers off, it only picked 5 HP- that is unbelieveable. I have twice seen the mufflers make MORE HP than the open headers. You cant beat it. THey are prrtty quiet too.

JOE SHERMAN RACING ENGINES

shoedoos · Post by **shoedoos** » Fri Apr 18, 2008 9:33 pm

found this in my travels....

http://www.broaderperformance.com/muffl ... test-A.htm

Horsewidower · Post by **Horsewidower** » Fri Apr 18, 2008 9:35 pm

I decided not to use Flowmasters when they refused to tell me how much CFM they were rated at. They don't "rate them that way." I'm not sure what other way would be relevant. Maybe they've changed since then, but I've never checked since.

Bob Holmes

steve z · Post by **steve z** » Fri Apr 18, 2008 9:43 pm

tried flowmasters a few years back on a 496 BB chevy deal, lost 50 hp on the dyno. we only use dynomax race bullets now. a little noisey but NO hp loss

sleeper sedan · Post by **sleeper sedan** » Fri Apr 18, 2008 10:02 pm

Tom (Hand) is a good friend that turned me on to a great HD muffler...

http://www.goerlichs.com/product_sub_pa ... erator.asp

As tested [by Tom], they are quiet and offer a very minimal hp loss. He will tell you, as well as others, the Flowmaster are what we'll call... sub-optimal. <snicker>

The Goerlich muffler I purchased I have yet to run. They are a very large chamber, 3" in, 3" out, and a perforated straight pipe running through the center. They may not be for everyone, for my project (my dad's) it's a walk softly and carry a big stick scenario.

There are a some very good mufflers out there in the market, it's hard to go wrong. If you like load, excessive noise tickets, and hp loss then the Flowmaster fits the bill.

Clark

Keith Morganstein · Post by **Keith Morganstein** » Fri Apr 18, 2008 10:08 pm

Flowmaster is an example of what good advertising and a lot of support from the magazines can do for a lousy product.

They sound like crap IMHO

RW TECH · Post by **RW TECH** » Fri Apr 18, 2008 10:52 pm

I had the same poor experience with them on a budget drag car years ago. It lost .17 and 3 MPH every single time the mufflers went on.

Of course, I'm a slow learner so I let the local custom exhaust guy put some on my Corvette. After a 50-mile trip my ears are pounding from all the low-frequency booming noise.

Pure junk.

bigjoe1 · Post by **bigjoe1** » Fri Apr 18, 2008 10:58 pm

I tested the longer Magnaflow mufflers ( 18 or 19 inch case) they actually made a few more HP than the shorter (14) length, The longer ones are soo quiet, you can hear the lifter noise and piston slap on startup. The ones I use on the dyno are about half as loud as flowmasters. I never have to wear head phones when I run the dyno anymore.

JOE SHERMAN RACING ENGINES

rrp · Post by **rrp** » Fri Apr 18, 2008 11:15 pm

We had the same thing happen when a customer used the flowmasters. It was a 10 teen 454 in a chevelle. With the flowmasters on it would run 10:50 I don't remember what series they were though, but he was proud of them until he took them off and then the car ran right where we told him it would.

econo racer · Post by **econo racer** » Sat Apr 19, 2008 12:23 am

If I had to guess-You guys are mainly talking about the 2 chamber flowmasters-I run the 1 chamber 3 inch on my BBC-Sounds like 1000 hp but realisticly 550 hp-I run 2- 5 inch long straight thru shoenfields at the ends- Tried to quiet it down-Probably a decimal at the most. I can't see how the 1 chamber could hurt-Mr Sherman have you ever dynoed the 1 chambers yet? Yrs ago I ran 7.4 1/8th mile with a sbc-Ran Dynomax super turbo-Took the exhaust off and it did not pickup anything