What RPM range do YOU get the best mileage at?

[guudasitgets]

Seems like 2600 rpm

[EcoCivic]

This is interesting. I always thought upshifting as soon as possible without lugging the engine when accelerating and cruising in the highest gear possible under light loads resulted in the highest MPG until I started testing it and realized that isn't always the case.

[Ecky]

Originally Posted by EcoCivic

This is interesting. I always thought upshifting as soon as possible without lugging the engine when accelerating and cruising in the highest gear possible under light loads resulted in the highest MPG until I started testing it and realized that isn't always the case.

It seems to be the case with my wife's Fit. She's having a lot of 60-70mpg trips lately, and she's a notorious shortshifter.

[GreenTDI]

Feel the engine and the car. What I'm doing is not blindly following the gear shift indicator. It tells me to shift to the next gear at 1600 rpm. If i do that, the engine will drop at idle speed. So according to the BC, the most economical RPM range is between 800 and 1600 RPM... But there is no power at all and acceleration takes way too long. Perhaps it works with larger 6 or 8 cylinder engines. But not with a tiny turbocharged 3 cylinder diesel.

But on the other hand, power (=working turbo) costs fuel. Or so the BC thinks ...

[skyking]

General rule of thumb for the diesels is @ peak torque RPM.
My fleet agrees with that, having happy gearing around that speed.
ALH TDI is about 2000
5.9 Cummins ISB is ~1650
Both of those are around 55 MPH in the top gears. I re-geared the truck higher to get there.

[EcoCivic]

I hear all the time that engines run most efficiently at the RPM they make peak torque at, but if that was the case I would be most efficient at 5K+ RPMs. Or maybe that is only true at full throttle on gasoline engines?

[GreenTDI]

Originally Posted by EcoCivic

I hear all the time that engines run most efficiently at the RPM they make peak torque at, but if that was the case I would be most efficient at 5K+ RPMs. Or maybe that is only true at full throttle on gasoline engines?

The most efficient power boost, probably. Not for the best fuel efficiency. That should be at the point where the engine delivers a comfortable amount of power for the speed driven. At legal speeds, that is mostly at lower rpm's with both diesel and petrol engines.

For my diesel it is between 1600 - 1900 rpm. Maximum torque at 2200 rpm.