View Single Post
  #23  
Old 11-12-2007, 09:59 PM
Matt L Matt L is offline
Registered User
 
Join Date: Oct 2005
Posts: 4,263
Quote:
Originally Posted by BIGRED View Post
The higher the compression ratio / compression psi the more effort it will take to rotate through compression. I know that the amount of force I need to use to rotate our 530it a 3 liter gas engine is a fraction of that which is required to rotate our diesel a 3 liter diesel.
This is not relevant. If you rotate a one-cylinder engine, even in the absence of leakage you notice the compression force. If you rotate a six-cylinder engine fast enough, the expanding gas on the "power" stroke counteracts (nearly exactly) the compression strokes on other cylinders.

The power that it takes to rotate the engine to start doesn't mean anything, since at very low speeds, there is a lot of leakage and thus a lot more pumping loss.
Reply With Quote