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Originally Posted by The Rookie
Wow talking of total bunkum......where did you pluck that from....
On a steady cruise the best FE is at the lowest road speed without ending up going rich (due to EMS fueling strategy in whatever car your driving), so sme cars you have to speed up a little on grades to keep it from going rich, best FE at rpm of somewhere near best torque ..... where is the logic for that? That would be at about 7000rpm in a Honda S2K!
As for tuning to idle economically, very difficult, and most manufacturers only tune it to idle economically when stationary, most jack the idel whe moving, and on manual cars retard the ignition to add a torque reserve in case the clutch suddenly comes up!
Simon
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Simon-
Since you seem to know so much about this, perhaps you could explain the difference between an engine's torque and its horsepower?
Honda S2000s are one of my favorite cars, but not because it's a torquey engine, but because it's the highest horsepower per litre non-aspirated production engine made (at least up until the last few years, may still be), but note that it makes no claims on highest torque.
I'll give you a clue, the little torque it does make is in the upper third of its incredible RPM range. And yes, where it's maximum torque is, is where its best gas mileage will be found...find the gear where the desired road speed (let's say 55 for grins) puts the engine in that range, and that's where you find the fuel consumption sweet spot.
You're right about tuning for idle, it's a stupid thing to do, I wasn't suggesting it. But as the price of gas goes up, our craving for horsepower and performance is going to shift to getting good gas mileage...
Funny thing, back about 50 or 60 years ago, when folks weren't as affluent as they are now, car manufacturers were installing overdrives on cars...it was quite common for the overdrive system to be free wheeling when you let off on the gas...essentially putting system in neutral, to save on gas...yes, they were carbureted back then, but not for maximum horsepower...they were tuning for torque.
-Quick