how does a power band on 2 stroke engines work?

Question

I know that power band is a term to describe the range of power in engines, i know a quite a bit about engines in general but im still not understanding where the boost in power comes from in the high RPM's of a 2 stroke engine? Is there a more technical term than power band?

Answer 1

Generally, the peak horsepower is just a little lower than your redline. And usually the peak torque is at low-to-mid rpm. The powerband is a term for the range of rpms from peak torque up to peak horsepower. If you think about it in football, the best way to take out a quarterback is to run as fast as you can at him...that is power. But if you were going to lift the quarterback back up, you wouldn't try to throw him up, you would try to lift him up at mid speed...that is torque. Hope this helps.

Answer 2

2 Stroke Power Band

Answer 3

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RE:

how does a power band on 2 stroke engines work?

I know that power band is a term to describe the range of power in engines, i know a quite a bit about engines in general but im still not understanding where the boost in power comes from in the high RPM's of a 2 stroke engine? Is there a more technical term than power band?

Answer 4

Without getting into a bunch of technical crap it's basically like this. In a 2 stroke you can spread the power more evenly across the RPM range, but this hurts your peak power, so what they do with most 2 stroke races bikes is concentrate almost all of the power in a small range. This makes 2 strokes much harder to go fast on since you can't keep the throttle near wide open through all of the obstacles and turns on a motocross track. This is most apparent on smaller 2 strokes (125cc and under). When people talk about "hitting the power band" they simply mean that they reached the RPM range where the bike starts to make real usable power. A 4 stroke is able to create power throughout the RPM range without sacrificing peak horsepower which is one of the many reasons they dominate motocross/supercross these days.

Answer 5

On a racing dirt bike ( CR, RM, KX, YZ, etc.) the extra kick comes from a properly designed exhaust pipe (also called expansion chambers). If the first part of the pipe (expanding cone) is the right length and diameter AND the last part of the pipe (converging cone) is the right length and diameter, positive and negative energy waves bounce back and forth in there. At some point in the RPM range these pulses actually draw more air/fuel charge into the cylinder then bounce back to stuff the excess from being drawn out the exhaust port and THEN the power starts to happen. Have you ever heard anyone say, "It really comes on the pipe, or, thats when (rpm) it comes on the pipe). It took a long time before engineers really understood how expansion chambers work. People (companies) who make pipes for racing 2 strokes put alot of time into a pipe to get it right.

Answer 6

I've heard before that on 2-stroke dirtbikes there is actually another valve that opens up when the carb is at just a certain point which in turn produces more kick. but generally i'd just say its just the motors sweet spot, in RPM's, where it performs it's best.

Answer 7

the jet switches and the expansion chamber makes torque