2cycle pipe question proly just another dumb question

paulkish

paulkish

old fart
On most all 2cycle pipes I see just one outlet for exhaust.

Instead of one or maybe two large holes wouldn't a ring of smaller holes around the pipe with the same area to release burnt gasses be better?

I'm thinking it would because I think it would disturb rebounding sound waves less or at least make how they are disturbed more even.
It might mean pipe lengths would need altered but the end result may better utilize rebounding sound waves.

Another dumb question: Do the various directions of acceleration alter engine performance because of how acceleration effects air inside the pipe?
If so might there be and optimum mounting angle of a pipe for performance?

... ????? don't know just happen to be thunkin bout pipes this morning.
 
1) If you look up how air flows through a hole in a flat plate, you will find that a single hole of a given area will flow more air/fluid than a number of holes equaling the same area.

2) The main function of the pipe is dictated by sonics, and that won't care which direction the pipe is oriented.

PM
 
thank you Pete

We used a Kb01 on our K30 and had 2 holes in it instead of 1.
Engine was nothing special but it was always as good as or better then any K30 others had.
For no good reason I got to thinking about the two holes on the pipe and one thought wondered to another. ... :)
Fun thing with the two holes was I put angry eyebrows above the two spaced apart similar to eye spacing. ... :)
 
IMO the outlet hole only serves as the exit for the spent gases & doesn't have any effect on the waves between the divergent & convergent cones. And on the pipes that have 2 holes & we might cover 1 of the holes is because the pipe was designed for a larger cc engine and it doesn't have enough back pressure (and heat) on the smaller cc engine to properly give a return exhaust wave.

IDK, maybe I'm wrong. This stuff is probably way over my head anyways.

Brian #89
 
The diverging and converging cones control the wave as stated . Now the stinger length and diameter come into play also , so the outlet would seem too have some effect . The can is basically there to quit things down isn't it ?
 
phantomkartracer said:
IMO the outlet hole only serves as the exit for the spent gases & doesn't have any effect on the waves between the divergent & convergent cones.
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I
Actually, because wave speed is so dependent on the temperature of the air it's flowing through, and because 2 holes will lower the temperature inside the pipe more than one hole, the wave speed should be faster with one hole versus two. Theoretically of course. This will change the tune on the pipe.

Pipe shape also makes a difference. Irv K anamoto, when he was a team mechanic for Kawasaki, told me they tested pipes at the factory and they were all straight when tested. He wondered, how do they expect a straight pipe to perform the same as the pipe that is shaped to fit the bike. Yamaha in their SAE papers said, bends within reason. It all has to do with the heat of the air in the pipe. Bends may cause different heat patterns i.e. different wave speeds.
 
I do know that on direct drive pipes with the hole at the end that is not in the center if that hole is on top or you rotate it to be on the bottom it does make a difference. I didn't know back then but years later while testing some old engines with a factory engineer and a mechanic they told me it orientation does make a difference on those pipes for DD ICA engines though.
 
rainman said:
I do know that on direct drive pipes with the hole at the end that is not in the center if that hole is on top or you rotate it to be on the bottom it does make a difference. I didn't know back then but years later while testing some old engines with a factory engineer and a mechanic they told me it orientation does make a difference on those pipes for DD ICA engines though.
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Which direction is the better ?
 
Pete_Muller said:
Probably depends on the phase of the moon. :giggle:
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Good one Pete, lol. Changing topic a little bit, You know what was interesting to me when i moved to the US, especially the 2nd time when racing dirt ovals? I rarely saw scales at racks to setup karts in Europe. Of course a 50/50 right/left percentage for a sprint track might not make a scale so important unless you want a setup for a non offset that is not same for both sides considering the turns, but it called my attention once I learned ho to use them here. I really learned a lot racing dirt. Different perspective.
 
Scales definitely make the job easier! Way back when I started racing, we'd do a quick circumference check of the tires to make sure diameters were very close left/right, try and find a piece of flat ground in the pits, and check front corner weights by "feel". On track, just let go of the steering wheel on the straight and see if the kart wanted to turn slightly to one side or the other -- that was always my "go-to" for a quick check of left/right balance (twist in the chassis). It's a new era for sure -- lots of cool tools to make fine tuning (and documenting of that fine tuning) a lot easier and quicker.
 
Pete_Muller said:
Scales definitely make the job easier! Way back when I started racing, we'd do a quick circumference check of the tires to make sure diameters were very close left/right, try and find a piece of flat ground in the pits, and check front corner weights by "feel". On track, just let go of the steering wheel on the straight and see if the kart wanted to turn slightly to one side or the other -- that was always my "go-to" for a quick check of left/right balance (twist in the chassis). It's a new era for sure -- lots of cool tools to make fine tuning (and documenting of that fine tuning) a lot easier and quicker.
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Well to tell you the truth on one side most Europeans tend to think Americans don't know what they are doing, to stuck up in Europe on their own ways. On the other side it is true that back on time those guys could set a kart better than most people nowadays without any scales using many other inventions or tricks, but modern times in Europe has brought many new mechanics perfectly dressed but compared to those old guys they don't know what they are doing without a tool telling them. That's talking about chassis, because if we talk about engines the TAG era made most good builders/tuners retire overseas.
 
Jim46 said:
why did the tags put out builders ? I understand the sealed rotax
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More limited rules even if they are not sealed. Added to that TAG classes mostly run ame engine, like a spec class, not like when there were multiple brands running ICA. In the best scenario you have a TAG class with different brands if it is not a spec class, but you will rarely see more than 3 different brands involved. Besides and engine with strict regulations running lower rpms with a larger capacity (125cc vs 100cc in ICA) is much more forgiving reliability wise but they actually charge more for the work that they used to and even more when they are sealed like Rotax.
 
Pete_Muller said:
IAME has *really* upped the quality and consistency of their engines in the last decade as well. They are very, very good, right from the factory.

PM
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Agree in quality, but you at my favorite track in Spain when I go there I can be faster with an old ICA than the guys with modern Tags. I am even faster with my KZ Modena, even if it is a short track by today's sprint track standards (around 1/2 mile).
 
Back to the pipes , I was told a thin pipe will make more power or was it just quicker to get to the power
 
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