Cams for FE
 

hello again
i have a book called "how too make more horsepower" by david vizard and in it said that less lift helps fuel atomization (thus better fe), is this true?

and while i was looking at animations of how the prius' atkinson cycle works and i was wondering instead of leaving the valve open still in the compression stage, why not close it before it gets to bottom dead center, so there is less resistance in compression thus theoretically more fe
thanks

Re: Cams for FE
 

Closing the intake cam late is good for maximizing high rpm power as well as low rpm Atkinson type efficiency. Closing a cam before bdc will kill power everywhere.

Re: Cams for FE
 

and the reason for that is because then the engine is effectively working against itself to suck in air just so that it can burn less fuel.

Re: Cams for FE
 

Thats also the reason cars with variable cam advance retard the intake cams at cruise (reduced pumping losses).