Bullwinkle wrote:
>
> PaulH.
>
> Somewhere I thought I once read that an internal combustion engine gets its
>best
> fuel economy at something like 90% of full throttle. Now that doesn't mean
>90%
> of its mazimum engine speed, but 90% of FULL THROTTLE.
I don't have the details as you do, but this phenomena is
very true.
When the throttle butterfly is closed, every time the pistons
do an intake stroke they experience quite a lot of drag trying
to fight against the vacuum they are creating in the bore.
This parasitic drag consumes energy, which consumes fuel.
I wouldn't go as far to make an absolute statement, but when
running in overdrive, you are running at a lower throttle
opening and a lower RPM than without, so this phenomena could
come into play.
Although I still want OD in all my MGs, and I am 2/3rds
of the way there. ;>
--
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/
Just because it's rare doesn't mean anybody wants it.
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