Re: [alfa] Diesels and dollars

[bearbvd@xxxxxxxxxxxxxx (Greg Hermann)]

At 8:38 AM 5/26/04, webb.p@domain.elided wrote:
>> engines act more like an Otto cycle engine--the higher the injection
>> pressure, the FASTER they can get the fuel into the chamber, and the closer
>> they can approach a constant volume burn, and therefore the higher
>> efficiency of the idealized Otto cycle.
>
>This statement would only be true for mechanically injected engines.
>
>This is absolutely not true for electronic fuel injection.    It's not
>that simple by any stretch.   Sequential vs. batch, PWM, opening times
>etc....

Nonsense, Peter---in fact, get a clue !!

In an efi spark engine, the fuel is injected and evaporated long before it
is lit, the duty cycle and/or injection rate of the injectors has NOTHING
to do with the burn rate, as it most certainly DOES in a diesel. Even in a
direct injection spark engine, the fuel is injected during the compression
stroke, LONG before it is lit.

As for electronically controlled injectors in diesels (most notably the IHC
developed Power Stroke stuff), the actual injection rate IS faster than
with mechanical injection--because of higher pressure--which is NOT
generated by the electronics, but by mechanical/hydraulic pressure
multiplication tricks.

Greg
>
>-Peter
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