Intake Size - Larger Isn't Always Wise

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-Intake Size-

Larger Isn't Always Wise

The Question - Have you ever heard of the "90% rule" as applied to 2-stroke piston intake port size?? Wherein, the rule is: Intake piston port size (for the purpose of piston strength) shall not exceed 90% of piston bore size. Found on Eric Gorr's 2-stroke web-site. Comments??

The Response - I have not. But that means nothing, there's way too much I haven't heard of. I have Gorr's book - there are a number of good, model specific things in it.

Usually I calculate the intake size based upon a number of factors. Most specifically what type of intake system it uses; reeds, piston port, disc valve. From there I can calculate the time-area I'm shooting for - which will be just one part of the engines design parameters. There's much to consider when designing a motor for high output. It is probably best to think of the whole engine as a package that will perform at a target RPM for an intended purpose. Develop each area independently. Then build the engine to its entirety.

Rick

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Larger Isn't Always Wise
The Question - Have you ever heard of the "90% rule" as applied to 2-stroke piston intake port size?? Wherein, the rule is: Intake piston port size (for the purpose of piston strength) shall not exceed 90% of piston bore size. Found on Eric Gorr's 2-stroke web-site. Comments??
The Response - I have not. But that means nothing, there's way too much I haven't heard of. I have Gorr's book - there are a number of good, model specific things in it. Usually I calculate the intake size based upon a number of factors. Most specifically what type of intake system it uses; reeds, piston port, disc valve. From there I can calculate the time-area I'm shooting for - which will be just one part of the engines design parameters. There's much to consider when designing a motor for high output. It is probably best to think of the whole engine as a package that will perform at a target RPM for an intended purpose. Develop each area independently. Then build the engine to its entirety. Rick