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Author Topic:   Make hp with mufflers
mrutrac
Dirt Roller

Total posts: 18
posted October 28, 2002 09:06 AM
IMCA Hobbystock

Our tracks are requiring mufflers.... Has anyone found a good combination to make more hp instead of cost hp?... How long should the pipe be from the stock manifold? Where is the best place to mount. Just looking for some expert advise on the issue.

Thanks for making this a great forum.... I have learned a lot from you guys + gals and hope to contibute more as I learn..

Thanks

Mrutrac

The Outlaw
Dirt Maniac

Total posts: 159
posted October 28, 2002 11:03 AM
an old school rule of thumb, when you are running pipes, run them long and paint them, where the paint stops burning is where they start losing there efficiency, that was straight out of smokey yunicks mouth per stock car racing magazine! it also helps with low end torque coming off the corners! might have to run it a week or two before it burns where you need it.

mrutrac
Dirt Roller

Total posts: 18
posted October 28, 2002 11:11 AM
Thanks Outlaw!..... Nice tip

MruTrac

KPLugnut
Dirt Freak

Total posts: 408
posted October 28, 2002 11:29 AM
One thing I might add here....

That "old rule of thumb" is also now known to be somewhat of a wive's tale....the rest of the info many guys forget is that if you cut the pipe at the point where the paint stops burning and THEN repaint the pipe, you'll quickly find that the paint stops burning at yet a shorter length.
If one continues to cut the pipe where the paint stops burning, before long, you won't have any pipe left.....

It is a very crude way of determining rough collector lengths needed, but there are so many other variables (timing, pipe diameter, jetting, etc etc etc) that it can lead you down the wrong path to finding HP if you're not carefull.....

Hope that helps.

KPLugnut

outlawstock17
Dirt Forum Champ
Total posts: 620
posted October 28, 2002 02:24 PM
if they only specify a muffler and not a decibel level, i'd use the schoenfeld "louvered" muffler. i don't think they quiet down the engine much, but it is a muffler. another way to quiet the engine down WITH a HP gain is to use an "X" pipe. you will like it!

good stuff on the exhaust pipe KP. i've always wondered about painting the exhaust pipe to determine collector length.

mrutrac
Dirt Roller

Total posts: 18
posted October 28, 2002 03:04 PM
That makes sense... KPLugnut... I'll send you the carb shortly as we talked. The rest is pretty simle... 9.1 KB lightest flat tops - 441 heads - Probably a solid lift cam around 550 or so lift (any input welcome) - timing (any input welcome) must use stock Spark need to stay stock but I'm sure there are a few things I can do to the Hei setup....manifolds.. no center dump... no X or y pipe allowed. Any other detail needed?

I'm trying to dial in the right package and your imput really helps... rookie driver and crew... but we want to do ALL the little things needed to be competitive.

Thanks

Mrutrac

The Outlaw
Dirt Maniac

Total posts: 159
posted October 28, 2002 04:56 PM
yeah nevermind...whose smokey yunick anyway?? he never mattered did he? guess not! heard he built a helluva carbeurator though

Eljojo
Dirt Freak

Total posts: 273
posted October 28, 2002 04:57 PM
Excellent topic! I'm considering mufflers myself for next season,and was wondering which direction to take. www.castheads.com (Bresenski's) has a nice article on the exhaust system, but as with everything else they offer, their muffler is quite pricey.
I was wondering whether any noticable difference would be seen by fabricating one's own "Y" pipe and incorporating a straight thru design muffler. Any ideas?

outlawstock17
Dirt Forum Champ
Total posts: 620
posted October 28, 2002 06:01 PM
the outlaw......bite your tongue! smokey yunick was one the greatest racing innovators in recent history!

KPLugnut
Dirt Freak

Total posts: 408
posted October 28, 2002 06:07 PM
There was never any disrespect either direct or implied in my post, Outlaw. I have the utmost regard for everything Smokey ever did, tried, wrote about, built, or blew up. I met him once and will never forget it. All I was trying to do was relay to everyone here that it is a well-known misconception (painting pipes and cutting them) these days, and it's been proven a million times, even in the world of 4 cycle kart motors.
Again, I never meant to step on anyone's toes. Sorry if it came off like that, and I hope you don't think I was downplaying any knowledge of this that you have.

I'll ignore the crack about carburetors....

Don't go away mad...

KPLugnut

The Outlaw
Dirt Maniac

Total posts: 159
posted October 28, 2002 08:01 PM
kp...lol had to get that carb thing in, i made my point...not mad, just know what worked for me and others for years!

madmodshoe
Dirt Forum Racer

Total posts: 89
posted October 29, 2002 09:55 PM
call Schoenfeld headers!!! I met Mr. Schoenfeld(I think Don) at a performance seminar some time back. He is an old school type of guy who really does care about selling a quality product. They have always been on the money with advice and they are not priced as high as others because they don't overadvertise their product like others. Remember when a companies name is on the side of a race car, who pays for that? Not knocking product sponsors, but keep everything in perspective.

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