> bud-- wrote:
>>>
>>> Far and away the biggest problem comes from the basic
> thermocycles of
>>> adiabatic engines, i. e., gas turbines (Brayton/Joule/Ericsson
> I),
>>> diesel (Diesel) and spark ignition (Otto).
>>
>> The Prius uses a 4 stroke Atkinson cycle engine. Like a
> conventional
>> Otto engine, the air-fuel mix is optimum. But like a diesel there
> is no
>> throttle plate. Not pumping air past a throttle plate is supposed
> to be
>> one reason Atkinson has a higher efficiency. The effective
> compression
Is it the current engine model?
My recollection is that the intake valve closed earlier for high power
and later for low power but in a brief search I didn’t find a source.
The Wikipedia entry for the "Hybrid Synergy Drive" used by Prius
http://en.wikipedia.org/wiki/Hybrid_Synergy_Drive
(Performance) "the Atkinson cycle engine itself was also designed
specifically to minimize engine drag via an offset crankshaft to
minimize piston drag during the power stroke, and a unique intake system
to prevent drag caused by manifold vacuum versus the normal Otto cycle
in most engines."
The "unique intake system" is not described.
You may be right that there is a throttle plate, I don’t know.
--
bud--
