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

[Alexei Pavlov]

mos at sydney.net wrote:
> 
> On Mon, 16 Dec 2002, Alexei Pavlov wrote:
> 
> > pedward at apsoft.com wrote:
> > > The only way to eliminate throttle losses is to have no throttle at
> > > all.  You then do the throttling via modulation of the valve timing.
> >
> > Could you explain why there are no pumping losses with variable valve
> > timing or clearance ?
> > I see variable valves exactly like throttles, the piston still has to
> > pump the vacuum to reach the BDC. The energy loss is still here.
> 
> Are you guys talking about variable valve timing? or variable valve lift?
> 
> You'd need some large amount of timing variance to be able to control
> cylinder filling with timing alone.
> 
> Continously variable valve lift is probably more than beyond the scope of a uni team.

I was asking about the continiously variable lift (like the BMW's one).

> 
> On a more related note - with no pumping losses a cylinder will fill
> completely with its volume at ambient pressure - is there a way, other
> than making it harder for the air to enter, to limit the filling mass?
> More to the point - is it possible to have cylinder filling control with
> *no* pumping losses.

In fact, that was my question :-) Is it possible ?

> Letting it fill completely then releasing some before compression?

Why not ? Any idea about how and where to release the air ?

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