[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: Fuel economy (was Re: Pressure Acummulator Discoverie
>I thought the most 'efficient' use of the engine was to shift up to the
>next gear so that the engine will be at its torque peak. Is this my
That is the way to get the most _acceleration_, not the most _efficiency_.
You get the most efficiency (i.e., lowest fuel consumption) by accelerating
with a wide open throttle and shifting as soon as your rpm is high enough that
the engine will not lug in the next gear.
The reasoning behind this is that throttling an engine is restricting the air
flow, and that energy is required to "pump" air through the restriction. If
this sounds a little looney, then think about the huge volumn of air that
passes through the engine for every liter of burnt fuel.
The second part of the reasoning is that you will use the least fuel when in
the highest possible gear, simply because the engine will turn fewer times per
BTW, this is part of the reason for higher diesel fuel efficiency - no throttle.
In addition, it is, to my mind, the biggest drawback of automatics. If you
open the throttle, the d*@$ thing will downshift on you. It is not possible to
drive an automatic in a fuel efficient way. I'd bet that if the EPA tests were
re-run using the full throttle early upshift technique you would see a greater
disparity between manual and automatic fuel economy figures.