4 stage pipe

alvin l nunley

Premium User
What's the advantage, if any, in these types of pipes?
Maybe this explanation is too extensive, but I'll try.
When the exhaust valve opens, it sends a pressure wave out the pipe, when that pressure wave reaches the end of the pipe, as it expands, it creates a negative pressure wave traveling back up the pipe. This negative pressure wave, ideally, lowers the pressure in the cylinder allowing more flow to be pushed into the cylinder through the intake valve. A multi-staged pipe does this more often, but at a lesser effect at each expansion. Instead of having one large expansion, which will affect the engine at just a narrow RPM range, you get a bunch of small expansions over a larger RPM range. I have no dyno data showing whether it works or not.
 
Maybe this explanation is too extensive, but I'll try.
When the exhaust valve opens, it sends a pressure wave out the pipe, when that pressure wave reaches the end of the pipe, as it expands, it creates a negative pressure wave traveling back up the pipe. This negative pressure wave, ideally, lowers the pressure in the cylinder allowing more flow to be pushed into the cylinder through the intake valve. A multi-staged pipe does this more often, but at a lesser effect at each expansion. Instead of having one large expansion, which will affect the engine at just a narrow RPM range, you get a bunch of small expansions over a larger RPM range. I have no dyno data showing whether it works or not.
Thanks Alvin, you explained that about as well as anybody could to someone like me who is trying to wrap my head around this stuff lol
 
Thanks Alvin, you explained that about as well as anybody could to someone like me who is trying to wrap my head around this stuff lol
How about the length of pipe? It may be a stupid question, but I bought a 4 stage pipe, and it's a shorter one, so I feel it's too close to my shoulder as I'm sitting in the kart. I've been burnt badly with my clone pipe and don't want to go through that again.
So is the length of the pipe irrelevant?
 
How about the length of pipe? It may be a stupid question, but I bought a 4 stage pipe, and it's a shorter one, so I feel it's too close to my shoulder as I'm sitting in the kart. I've been burnt badly with my clone pipe and don't want to go through that again.
So is the length of the pipe irrelevant?
Just an FYI, i am big guy, 250 lbs, so that's an issue lol
 

flattop1

Dawg 89
Length is relavent .
As is not getting burnt !
 

alvin l nunley

Premium User
How about the length of pipe? It may be a stupid question, but I bought a 4 stage pipe, and it's a shorter one, so I feel it's too close to my shoulder as I'm sitting in the kart. I've been burnt badly with my clone pipe and don't want to go through that again.
So is the length of the pipe irrelevant?
The length of the pipe is established, by the builder, with multiple tests on the dyno. I'm almost sure of that. That's how I did it with my 2 cycle expansion chambers. Length is most relevant! A very "key" design consideration.
 
Length and ID of the primary, or main stage, is the most important.
Any stages beyond that will simply broaden/smooth the power band. (again, assuming that the pipe is built correctly)
Consider that we race at a variety of engine rpms (ie you're not running at the same rpm always.)
 

OVALTECH1

Premium User
Tube length helps build you some torque. To an extent.....like anything flowing something there comes a time where it all just becomes lazy.
 

XXX#40

2A supporter
Tube length helps build you some torque. To an extent.....like anything flowing something there comes a time where it all just becomes lazy.
And thats why the different stages, and why its best to wrap the pipe, helps improve the pulse scavenging effect
 

alvin l nunley

Premium User
And thats why the different stages, and why its best to wrap the pipe, helps improve the pulse scavenging effect
The speed of sound (pulse scavenging effect) changes with the temperature of the air it's traveling through, substantially. It's about 1 1/2 ft./s per degree. Wrapping the pipe retains the heat of the exhaust pulse thus changing the speed of the "pulse scavenging effect". Depending on your engine, and/or it's modifications, that could help, and that could hurt. Only testing will tell for sure.
 
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