Quote:
Originally Posted by 3-Wheeler
Since we are trying to save fuel, it makes sense that going up the hill slower takes less energy (think force times distance divided by time or F * D / T). However, taken to an extreme, going up a hill in first gear may use more fuel than going up in third for example.
I always watch the FCD
If we go up the hill slower, use less energy, then it goes that there should be less heat as well, and less cooling requirements from the radiator.
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What is FCD?
The contradictory thing is that instant mpg is lower going up in 5th than in 4th, unless the speed is significantly less, giving the appearance of less energy used (less fuel) and less heat generated in 5th gear. On the other hand, I could always spin up a hill faster in a moderately low gear on a bicycle than a higher one, the sweet spot being 96 to 102 rpm. However I didn't equate that to energy use, figuring I was using more energy but the leverage was more optimal. Also, using a too high of gear on a bicycle changes the dynamic to strength. Maybe there's not a relationship to a car, except to see that higher rpms up to a certain point can be good, but maybe it's the same in a car, as the higher rpms provide better leverage, and thereby, (assumption) less heat.
I do think the higher rpms would reduce mpg, though that's a secondary consideration to keeping cooling in range.