TheLion70x77
Well-Known Member
Agreed. That's why I said what I said. Power matters. Not torque. Torqe and RPM just determine where the greatest power is made and consequently the most work is done. A engine making only 1 ft-lb of torque but that revs out to 100,000 RPM is making 19 HP while an engine producing 10 ft-lbs of torque but only revs out to 5,000 RPM makes only 9.5 HP, half despite making 10x the torque. Then you just need to use gearing to compact the power band to the optimal travel distance. Obviously the low torque motor needs very short gearing to do all of it's work in the same distance as the low RPM torqy motor that will use taller gearing. But the acceleration of the low torque motor will be much higher in the same distance traveled because of it's power advantage. All the fastest cars are spinners.Sorry, no.
Torque is not "one pound raised one foot". Torque is "one pound applied about an axis at a distance of one foot." There is a fundamental difference. Work involves movement, torque does not.
One way to tell (which very few non-technical folks seem to care about) is that torque has a unit of lb-ft while work has a unit of ft-lb... sure there's no difference mathematically, but there is in text.
Now don't forget you can measure angular work... you just need angular displacement... or 2pi * number of revolutions.
Then just like work = force x displacement... angular work = torque x angular displacement.
Top Fuel = 8 liter, 10,000 RPM, 59 PSI boost. 6,000 to 8,000 HP est (no dyno can measure that much)
Fomula = 1.5 L NA, 20,000 RPM or newer 12,000 RPM TT V6
NASCAR = 9,000 RPM small blocks...750 ~ 800 hp.
All of them are high revvers. Formula is the extreme example of low torque, high RPM engines. NASCAR is in the middle. Top fuel is crazy high in both, but wouldn't be making the power it does without revving out crazy high.
Work done is what we are after. Formula car engines are the perfect example. They now went to twin turbo V6's, but previously they were running 1.5~1.6L NA engines with fixed valve train. Yes fixed. 20,000 RPM. Only 300 ft-lbs of torque, but over 650 HP.
Why go that route? Weight. Small engines that rev to the moon can generate as much power as much heavier engines that operate at much lower RPMs. Formula cars are about maximizing power to weight ratios and applying it through extreme chassis designed for maximum grip. I illustrated the fact that power to weight ratios are a far better indicator of acceleration than torque to weight ratios.
I like to think of it was PWM signals. You can take a wave form with a higher amplitude (taller wave form), but at a lower frequency and you'll produce less average power than a lower wave form at a much higher frequency. It's a good visual to represent each stoke of the pistons. Even though at higher RPM's the thrust at the crank is less per a revolution, the number of strokes applying torque are far more, so the actual work being done is greater.
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