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understanding the tuned exhaust made easy!

Snowmobile How-To's

 
 
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  #1  
Old 11-15-2010
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Default understanding the tuned exhaust made easy!

I am no engineere or phisicist by any means. barely smart enough to be a brain surgeon.

parts of the pipe starting at the engine.
head pipe is the part of the pipe that goes from the manifold to the begining of the first cone.

first cone, is the diffuser cone, its where the pipe gets big.

center section is the main big body from one cone to the other.

baffle cone, or the cone that goes from big to small.

stinger pipe is the little pipe that goes from the end cone to the muffler.

the theory of operation of the tuned pipe is pretty neat and simple when you look at it from basic physics or theorys.
the diffuser cone creates a low pressure system in the pipe, it helps draw the fresh air charge from the crank case up to the combustion chamber. if the exhuast was a straight pipe from that point on you would have a lot of raw gas getting sucked right through the engine and into the exhuast pipe. that is why there is a second cone. it sends a wave back to the engine to stuff the compression chamber and stop fresh gas and air in the cylinder. this happens in about 4-5 thousanths of a second.
the angle and length of the cones also come into play where the power curve is.
the center sections length is basically sized based on the rpm, stroke, and bore of the engine. by changing the length of the center pipe you can raise and lower an engines rpms.
the size of the stinger pipe is based on flow requirements as well. it looks like a little piece of straight pipe but make it to small and the pipe cant get rid of the hot gasses fast enough. drag racers use this to make hot pipes for quick hp. they only need to make hp for 5 seconds but they need the pipe hot and hp there from the starting line. if you make the stinger pipe larger you let more air out. it can make for a good radar pipe or mountian climbing pipe where you are on the throttle for long periods of time.
as you change elevation you are changing dynamics in the pipe. that is why some mountain sleds will have an adjustable stinger, as they move up and down elevation they can simply adjust there stinger pipe to maintain proper operating power.
there is basic math rules to all of pipe building that most builders use as a guide line. stinger pipe size for example is usually .58-.62 the size of the head pipe.
pipe builders use basics to get a good starting point. experience and time on a dyno or computer simulators fine tune a pipe to be the best it can for what the maker wants.
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  #2  
Old 11-15-2010
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as you change elevation you are changing dynamics in the pipe. that is why some mountain sleds will have an adjustable stinger, as they move up and down elevation they can simply adjust there stinger pipe to maintain proper operating power.

Is this why my Aaen pipe doesn't seem to work very well in the mountains? I can go like a raped ape at 1,400 ft where I usually ride, but the new pipe is no better than stock when I get over 7,000 ft.
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Old 11-15-2010
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Yes, same reason some of the SLP pipes are high alt only or just plain don't work down low.
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  #4  
Old 11-15-2010
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Quote:
Originally Posted by Powersledder View Post
Yes, same reason some of the SLP pipes are high alt only or just plain don't work down low.
I'm not terribly stoked to hear this beings I just bought a SLP set up for the rmk.
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Old 11-15-2010
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I was mainly referring to their new 800CFI Pipe which is high alt only. And there are a couple other pipes from different manufactures that can be very finicky to alt changes
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Old 11-16-2010
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looking at SLPs directions for my ultra, I almost need a second set of carbs to change onto as I go up. they change ALL the jets and needles over 8000. looks like they had 2 sets of pipes for that sled. one they even had a set of heads to go with it to raise compression at the higher elevation.
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  #7  
Old 11-16-2010
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as you go up in elevation the engine has less running compression. that is why slp makes special heads for sea level sleds running some of there pipes. its all about energy conversion, heat, speed of the wave in the pipe. take a stock polaris twin, the harder you run it the stronger it seems to get. but if you have to putz through a town the pipe gets cold and the sled seems to get burbely. for the first moments on the trail the sled just inst there. but back on running hard and it comes back to life.

before getting any slp products you need to look and see what you need to run there pipes at your elevation.

cant you get 85 octane in the mountains?
if you had a second set of heads cut for high elevation that would bring back alot of the lost power.
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aint no body ripin like me. M to the a-d-c-o-w. rock it hard for my fly ladies. I rock it yes in deed. homies still roll with me. money dont change me


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  #8  
Old 11-16-2010
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Forgot to post it earlier, but nice writ on Jon. This will probably help a lot of people out.

And Gerbs, you're probably going to want to get the high and low alt SLP heads.
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  #9  
Old 11-16-2010
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thanks i thought it was better than posting a 170 page book i downloaded that i have in my documents. there are no original thoughts anymore, simply revised things we have learned.
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aint no body ripin like me. M to the a-d-c-o-w. rock it hard for my fly ladies. I rock it yes in deed. homies still roll with me. money dont change me


nothing goes like 3 holes.

BRTECH HOODS
high performance engineering
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