Patton Dickson wrote:
> My possibly incorrect assumption is that higher speed effects flow of
> fuel matters due to wind and road resistance, but fuel consumption would
> be constant at 4,300 RPM's regardless of speed. So, if you can get the
> engine turning higher in those lower gears, wouldn't it take about the
> same amount of gas to make it spin that high in 4th or 5th (THAT FEELS
> WEIRD TO SAY).
You were right the first time, the load on the engine is much
higher at higher speeds, and the fuel consumption is much higher. You
probably also have the throttle more wide open to acheive this.
The rationale is that the engine can hit 4300 rpm more easily in
lower gears and can do it with less throttle opening and therefore
more fuel. In top gear, it requires a larger throttle opening to
allow more fuel/air in to make that power.
If you think about it, compare the effects of holding the petal
on the floor for ten seconds in idle, first, and fourth. In first,
the engine has a low enough load that with that amount of fuel and
air it would turn at 10,000rpm if it holds together. In fourth, many
cars won't even pull to redline no matter what.
It would be nice if the engine used the same fuel per rpm in
all gears, because then we could all just have 10 speed gearboxes
and top gear would get you 100mph at 500rpm and 150mpg!
--
Trevor Boicey, Ottawa, Canada.
tboicey@brit.ca, http://www.brit.ca/~tboicey/
[ Seeking some miscellaneous MG parts, see the list on the web page... ]
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