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Old 12-06-2010, 07:20 PM   #157 (permalink)
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Originally Posted by NeilBlanchard View Post
I don't think you get the work back from compressing the valve springs -- the springs cannot be 100% spring back, they are pushing on the cam shaft, which is geared down, and there is a lot of friction involved in both directions. Can you imagine trying to spin the crankshaft by turning the crankshaft?
Actually, you can and do, with only the heat lost in cam/rocker/lifter friction and spring internal damping. Mechanical advantages do not lose work energy. No imagination necessary.
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