I don't agree with ifidonlike

if his opinions are true as in 84103's post. And I mostly agree with 84103's rebut. But saying max power has nothing to do with acceleration is wrong too. Max power limits engine performance when it is reached just by definition. Max means up limit, doesn't it? Max power limits the torque you can get when max power is reached, just divide max power by corresponding rpm. You get the torque you can get and thus determines acceleration.

In fact, power becomes limit even before max power is reached. Take a look at torque/power curve 84103 provided, why does torque drops after 4000rpm? The engine is certainly capable of providing 300Nm even at 2500rpm. Now it works harder, but why torque drops instead. Why torque plummets after max power is reached? Why can't torque keeps flat till red line? Because, somewhere between where max torque is reached and where max power is reached. Engine performance changes from torque limit to power limit.

You actually can feel this yourself. I will bring up 100m race again, and hope most people have done it. When you start, you kick the ground the hardest. And you feel the kick back from ground on your ankles, your knees and your hips. How hard, maybe 150 pound, 200 pound, no less than your weight if you can squat down and stand up on one leg. (I can do it) Once you go faster and faster, you feel the kick back from ground less and less. You tell yourself "What's wrong with me? Why my kicks get weaker? My legs are strong and certainly capable of kicking harder. Try harder!" No use, you mouth is wide open, you breath heavily. Your heart is pounding fast. Yet your kicks get weaker and weaker, until you reach max speed. How hard you kick now? Equal to the resistance. Do you feel significant slow down when both your feet are in the air? (That's the definition of running) Probably not, this means resistance is much less than your weight, say 10%. Now you only kick with 15 or 20 pound. Why can't you still kick with 200 pound? Because, you need to have 10 times more power and becomes a superman. Somewhere during the acceleration, when you start to feel you kick weaker than what your legs are capable of doing. You go from force limited (limited by how strong your legs are) to power limited. Car engines are about the same.

所有跟帖： 

• Max hp decides max track speed -Bonbon330S- ♂ (658 bytes) () 12/08/2005 postreply 16:19:59

• 回复：Max hp decides max track speed -kfbai- ♀ (432 bytes) () 12/08/2005 postreply 17:11:27

• And -kfbai- ♀ (199 bytes) () 12/08/2005 postreply 17:22:57

• 回复：And -Bonbon330S- ♂ (681 bytes) () 12/08/2005 postreply 17:51:19

• You are right that one -Bonbon330S- ♂ (847 bytes) () 12/08/2005 postreply 18:22:54