I have a manual transmission and was under the impression that a certain RPM on a particular gear will always generate the same MPH. The other day I noticed I sit at 2,800 RPM in 6th gear @ 80 MPH, and other times it’ll be at 3,200 RPM – Could some explain?
In: Engineering
I may be wrong, but what came to mind is the incline. RPMs provide torque on the axel, propelling the car forward. It’s not directly converted to MPH, which you notice when you press the accelerator and the RPMs zoom up but the car’s speed gradually climbs up. So, with RPMs providing force, the changeable part here since everything else is the same, is the amount of energy required to stay at 80 MPH. If you’re going uphill, you need more energy to continue at the same speed than if you’re going downhill. Your two RPM measurements weren’t far off, so it could have been a small incline difference.
TLDR: Uphill, level or downhill?
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