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Gas engine scavenging design

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Old 08-07-2007, 08:26 AM
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SAVAGEJIM
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Default Gas engine scavenging design

I am an RC fan but have only delved into the nitro aspect of it. Nitro engine use the loop (Schneurle) scavanging design, and I am wondering what scavenging design gas 2-stroke engines use. All the nitro engines I have seen and touched are all loop scavanging, I have yet to see a nitro engine that is cross scavanging.

Gas 2stroke engines from what I understand are cross scavanging mostly. But I want to know if this is true for RC gas engines. Do they also make loop scavanging gas 2stroke engines? Or are there a mix of cross scavanging and loop scavenging gas 2stroke engines in the RC world?

Also, as for mods, nitro engines are very easy to mod with a rotary tool since the sleeve pops out. How do you gas engine guys mod your largetr 2stroke gas engines? Are the sleeves integral with the block or do they slide out of the block like the little nitro engines' sleevs do?
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Old 08-07-2007, 02:23 PM
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Default RE: Gas engine scavenging design

i think there is a reson why cross scavenging is not widely used. loop has much better charicteristics to fill the cylinder. also all the biggies i have the sleeve doesnt come out.(at least not that i can see)
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Old 08-07-2007, 08:50 PM
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Default RE: Gas engine scavenging design

So that means the majority of RC hobby grade 2stroke gas engines are loop scavanging?
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Old 08-08-2007, 09:14 AM
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Default RE: Gas engine scavenging design

I have never seen a cross scavenging port lay out on any gas two stroke engine personally. That goes for all motorcycles, snowmobiles, quads, jet ski's, and these engines. They are all looped up the back of the cylinder.
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Old 08-08-2007, 06:48 PM
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Default RE: Gas engine scavenging design

well hey there earthsufer you havent been on in a while
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Old 08-08-2007, 07:39 PM
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Default RE: Gas engine scavenging design


ORIGINAL: Earth Surfer

I have never seen a cross scavenging port lay out on any gas two stroke engine personally. That goes for all motorcycles, snowmobiles, quads, jet ski's, and these engines. They are all looped up the back of the cylinder.
Thanks for the info. I have some knowledge on how loop scavanging engines can be modified for more performance, and I am now curious, how do you mod the cylinder of a gas engine if the sleeve cannot be removed? On nitro engines, the sleeve pops out and you can cut flow channels and even advance the timing profile with ease. How would you do the same on a gas engine?
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