GAS AND COMPRESSION DO'S AND DONT'S

[wrench man]

The reason that people blow up there blasters going down the road wot is mainly because they don't have them properly tuned (jetted, good oil and properly maintained).

BINGO!!!
I seized my engine once right after the rebuild during breakin, at WOT in sixth gear SCREAMING!!! down the beach! couldn't wait to try it out!!!!!, stepped up the main one size and haven't looked back!I:I

 

[hickskateboarder]

I maybe off but I read a page with diagram of 2 strokes tuning, the guy was saying that 2 strokes comp. will vary on rpm because of scavanging efficancy. so if you got say 10:1 on idle you could go up to 18:1 when you hit the powerband on the motor, because of the efficancy the motor reaches can be over 100%. idk if that makes any sense to any of you, but it did to me.

your right on the compression ration changing. it's called a dynamic compression ratio. it changes because of the increased velocity of the intake charge and "getting into the pipe" where the motor hits the right frequency to allow the pipe to supercharge the cylinder.

you are incorrect, however, where you say the efficiency of the motor exceeds 100%. this is impossible, even in a theoretical mannor. a carnot engine is the theoretical engine that is a 100% thermally efficient engine. and thats all it is... theoretical. it doesn't exist in real life. you'd be lucky to reach 40% thermal efficiency on any internal combustion engine.

 

[95BlasterRacer#107]

my main bearing locked up

 

[Kennedy_Power]

You are right Hick; some diesel engines are above 50% thermal efficiency. Gas engines are not close to that. You can achieve over 100% volumetric efficiency with turbo/ super chargers.

 

[misterww225]

you are incorrect, however, where you say the efficiency of the motor exceeds 100%. this is impossible, even in a theoretical mannor. a carnot engine is the theoretical engine that is a 100% thermally efficient engine. and thats all it is... theoretical. it doesn't exist in real life. you'd be lucky to reach 40% thermal efficiency on any internal combustion engine.

Well, not exactly. What he mean't to say was Volumetric Efficiency exceeding 100%. This means drawing in more volume of Air/Fuel than the engine displacement (200cc in this case). When you supercharge an engine by a 2-stroke pipe, turbocharger, or supercharger, you can exceed 100% volumetric efficiency. That the overall engine efficiency doesn't exceed thirty some-odd percent is correct.