In article ,
DavidR wrote:
The power output of a diesel is controlled by the amount of fuel
injected.

Yes, as a petrol engine.

No. A petrol engine is controlled by the amount of air admitted via the
throttle. Petrol is then injected to give the correct mixture. This is one
major reason why petrol engines are less efficient at part throttle -
pumping losses. There are developments to change this like using variable
valve timing rather than a throttle, but IIRC still only in development.

In principle is there any reason, other than the technical difficulty in
implementation, why a petrol engine couldn't have a fuel demand valve
connected to the pedal with the engine management determining the
necessary throttle setting?

Because petrol can only burn satisfactorily within a small range of
fuel/air ratio.

Not the same thing.

Diesel requires excess air. LB requires excess air.

The wherewithal to allow diesel to burn when injected is always present -
the air within the cylinders is compressed to a point where the heat from
this will ignite the injected fuel. Petrol engines don't and can't work
like this.

--
*The average person falls asleep in seven minutes *

Dave Plowman London SW
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