"Progressive shifting?"

[mcoyote]

So I'm listening to Car Talk on NPR this morning and a lady calls in and asks about the merits of "progressive shifting," which she heard about as a way to save fuel in big-rig driving school (she's part of a husband/wife truck driving team).

Basically, nobody was sure what it was but the thought was to start upshifting at relatively low RPMs and increase the shift point a set amount (e.g., 500RPM) as you work through the gears.

Tom or Ray (mix them up all the time) then chimed in and said that BMW discovered some years ago that, in fact, the most fuel-efficient way to drive a car was to always be almost lugging the engine and shifting "as soon as you can."

So, is this what "progressive shifting" is and can it help a motorcycle's fuel efficiency?

I am brought to this because it's winter in this hemisphere right now and we are burning oxygenated fuel and (for that or some other reason) my fuel economy in-town is painfully reduced.

(...Thanks! )



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[WWJD]

Hayabusa throttle + Feul economy = [divide by zero answer]

 

[cache]

shift at lower rpm = lower rpm = less fuel going through intake
on the other hand,
lower rpm = more effort to accelerate = less fuel economy
basicly, just don't hammer the accelerator all the time and you will save gas.

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[Revlis]

Actually Cache is pretty much on target.  I read a study a couple of years ago an basically they found that accelerating hard for a short period of time to a set speed uses about the same amount of fuel as accelerating gently to a set speed over a greater period of time.  

Basically, grip it and rip it!



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[mcoyote]

Interesting points.

Someone over at sport-touring.net pointed out that engines are more efficient when (a) at lower RPMS but (b) at WOT. (b) is true because the throttle butterfly/whatever obstructs the throttle bodies except when completely open.

This means that the most efficient design is an engine that runs at low RPMs at WOT naturally, i.e., with small throttle bodies. This, of course, means the engine has less oomph, which kinda cramps a sportbike's style I guess.

Oh well, as I said elsewhere I can probably manage -- tears dry quickly over 100mph.

 

[cache]

-- tears dry quickly over 100mph[/QUOTE]


yes, speed will heal most wounds...

remember: hayabusa is efficient, not economical.



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[WWJD]

I did get INDICATED 49.9 mpg on a highway run at aroun 75-80 mph. in town I can get 35, but usually average about 25-30 due to fun. I think that's pretty good overall

 

[Mikey D]

I thought progressive shifting was when you give it a tad bit o gas whilst on the clutch to keep the rpm's near where they should be when engaging the next gear. I know track cages do this, but maybe I have my terms mixed up?