[Diy_efi] Intro, and q's about fuel economy

Alexei Pavlov alexis.pavlov at st.com
Mon Dec 16 15:09:10 GMT 2002


> Using the valves to throttle the flow has different effects on the
> flow. It's still throttling; i.e. restricting.
> 
> The main difference is that with variable lift, that the gas flow
> speeds through the valves is higher and this results in greater
> swirl and filling of the chamber.
> 
> Further; the flow upstream of the valve is unthrottled, so it's at
> atmospheric pressure or greater, even when not supercharged. In
> essence, the vacuum the piston has to draw is out of a smaller
> volume; the cylinder itself instead of the whole inlet tract.
> (A bit of a simplification, but it helps to draw the mental
> picture.)

I would say that pumping from a large volume is easier than
from a small one. Am I wrong ?

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