Quote:
Originally Posted by redpoint5
How can a compression stroke be shorter than a power stroke? Are the con-rods variable length or the crankshaft morphs?
Also, why haven't gasoline engines been DI from the beginning, with no spark plug?
Last question, what is the difference between OTTO and Atkinson?
It seems to me the most efficient car would have a puny motor (3 cylinder 1L perhaps) and a turbo charger. Make this diesel with electric assist and regen and you would have one heck of an efficient vehicle.
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Q1: When the engine is in Atkinson cycle mode, the intake valve is open part way through the compression stroke, so some of the air comes back out to the ait manifold thing, then the intake valve closes and compression happens but the compression stroke in this case is shorter than the power stroke.
Q2: DI does not mean no spark plug, DI just means fuel is injected straight into the cylinder. No spark plug in a gas engine requires lots and lots of sensors and a fair amount of computation power. DI, I don't know why it hasn't been implemented from the beginning. Some cars many many years ago had DI but I don't why they didn't continue to have DI.
Q3:See Q1. With OTTO cycle, the intake valve is closed all the way thru the compression stroke, so compression stroke is around the same length as power stroke.