A Simpler Explanation Of The Measurement Of ONE HORSE POWER

jharrell wrote:

4x4ord wrote:
Keep in mind that reving the engine from 6000 rpm to 13000 rpm is only increasing the vehicle speed by a factor of 2.17. The Cat in my Peterbilt makes 400 HP by 1100 rpm, reaches a peak of 500 hp by 1300 rpm and holds the power flat to 2100 rpm. So even a big slow turning diesel can double the speed of the vehicle while maintaining 80% of its peak HP.

So real RPM matters here not just rpm factor. A Tesla model 3 goes 0-140 mph with a single speed 9:1 gearbox. That means its torque is multiplied 9x to the wheels across all rpms. Your diesel cannot do that, the gear ratio needed to run at highway speed would not multiply the torque enough off the line to get the vehicle moving and stall the engine.

Your diesel has 0 power and torque below what 600-700rpm because below that it stalls. The Tesla motor has max torque from 0-6000 rpm with usable power all the way.

Also you are comparing a 3000lbs diesel engine to a electric drive that weighs maybe 300lbs with inverters. The Tesla semi has 4 Tesla model 3 motors for 1000hp and 2000lb-ft of torque which weigh maybe about a 1000lbs with inverters. I would imagine the gear ratio is lower than 9:1 since they don't need to go to 140mph meaning even greater wheel torque multiplication.

Diesel are better than gas for sure when it comes to power curves, but they are heavier and more expensive to make due to the more robust design needed to take the high compression ratios and consequently torque numbers (along with direct injection and force induction). Electric still easily surpasses it though when it comes to power curve.

I agree that there are reasons to appreciate the capabilities of an electric motor. The only point i was making is that stating an electric motor has the ability to generate 80% of its peak power over a 7000 rpm operating range doesn't mean much when that operating range is from 6000 to 13000 rpm.