As a result of this topic coming up often on this forum, I decided to do a little surfing and find out a little more on the Hooker Max Flow mufflers. Here is what Hooker says about these mufflers:

Maximum flow for your sidepipes.
These Hooker 4 in. sidetube slip-in mufflers have been developed for vehicles with 4 in. sidepipes, such as those equipped with Hooker Super Roadster and side mount headers. They produce an average of 23 percent more power than open headers, and feature a high?flow, perforated core that operates at 99 percent efficiency. High-temperature packing material absorbs noise while producing a powerful, mellow sound. The outer case is constructed of durable 16-gauge aluminized steel and protected by electrostatically applied high-temperature black paint. The inlet and outlet are 2.5 in. perforated cores in a 4 in. casing.

So it looks like I can get rid of my JCL baffles and pick up over 100 horsepower on my 600+ horse 502, all with a 2.5 inch perforated core slip in muffler. What a crock of bull. This kind of arbitrary, irresponsible advertising crap really pisses me off. No mention of the motor tested or any testing parameters whatsoever. Am I missing something here folks? I am running the JCL baffles and on 2 occasions have dyno tested them as well as other mufflers. Is it just that nobody calls these bluffs or what? I have e-mailed Holley tech and I will let you know what they say. I guess some would read that and say great, best 140 dollars I could spend. I don't know anymore.

Bill

 

Nothing but the seat of the pants dyno here...

4" id

 

All I can say is that the guys down at Holley were very happy with the Maxflows while I was down at their shop, and this was while they were in the prototype phase. One of the guys in the Tech/R&D department down there has a 68 or 69 healthy 427 car that he dynoed with these and picked up quite a bit of power over the undercar system that he had previously. I had similiar results, I picked up a ton of power over my 1 7/8" primary hooker supercomps and Delta 50 flowmaster combination, when I went to the 2 1/8" primary sidepipe headers and a set of prototype Max flows. I'm not saying they are the greatest thing since sliced bread or anything, but I'd like to see them tested against the JCL's on the same car and see what kind of difference there really is, and if the difference is worth the cost difference.

Pat Kunz

 

Pat, thanks for the feedback. But really, a 23% increase over an open sidetube? That is the most ridiculous claim I have ever heard of in my life. What the hell does "operatates at 99% efficiency" mean? It seems to me if it can increase open header output by 23%, it is operating at 123% efficiency. My motor is out of the car at the moment for some freshening, I am tempted to buy a set of these for testing as I was going to put the motor back on the dyno anyway. Does anyone have any of these they would like to loan me for testing purposes?

When I was researching sidepipe mufflers back in 2001, I called Dawson's Headers to ask about their muffler I had heard about. At the time it was the only 2.5 inch core slip in muffler available other than Loback. From their description, it sounded just like a Max Flow. At the time my 502 was being transformed from a 350rwhp motor to its current 615 crank hp form. They told me any 2.5 inch system is going to be a restriction at anywhere near that horsepower level. I have confirmed that in my 2 dyno testing sessions.

Now I could believe it if they said a 23% increase over the reverse flows or glasspacks, because I lost 96RWHP on my car when the motor was in its 350 RWHP form. Isn't the Max flow a 2.5 inch glasspack? Granted the 2.5 inch core will help, but 23% over open headers, not on the planet earth.

 

Open headers are sometimes not the most efficient system - engines like at least a bit of backpressure.

 

That would be interesting to see!

 

I'm pretty sure they are talking about average power across the entire RPM range, not average (peak) power of many tested engines.

 

They are NOT talking about peak horsepower.. Somewhere in the RPM range they might make 23% over open headers.. Mufflers lower the RPM range of the engine and therefore more power comes in earlier. There's NO WAY that the PEAK performance will be higher with mufflers!

 

wow maybe I should get two for each side....hmmmm 46%...now were talking.

 

Yea, I agree. I, too have heard over the years where some engines liked a little bit of backpressure. Mainly these were the older TPI engines. I have, however never seen a dyno sheet showing proof of this. I would think if it were the case, it would have to be a seriously mismatched combo, where possibly there was some overscavenging going on.

I have seen about 5 different engines on both engine and chassis dynos. All but 1 of these there were some form of exhaust testing going on. In any of these cases I have never seen a muffler perform nearly as well as open exhaust, in either peak or average numbers. If anyone has any dyno sheets of any combinations where full exhaust made more HP than without, I would be very interested to see the combo.

Bill