Quote:
Originally Posted by brandonblt2
I agree as you indicated rpm cross over where torque and hp switch is a variable depending on the engine itself and not a constant that I thought it was.
|
No, the cross-over point does not depend on the engine at all. It depends on the
units used to express torque and power, and on the axis
scales used for torque and power in the plot.
It's actually unfortunate that by the pure chance of how the units of foot, pound, and hp were historically created (which was completely arbitrary, obviously), combined with the typical rpm range of car gasoline engine, the maximum hp and torque value of an engine are often numerically similar (in US units), like 200 and 150 (twins), or 200 and 250 (VW GTI), or 140 and 120 (Hyundai Accent), or 650 and 650 (Corvette Z06).
This causes people to use common vertical axis for both. Which is technically incorrect.
As a consequence, other people
wrongly assume that torque and power are two similar "forces" that contribute together to the same effect (car moving/accelerating), just one dominates in the low rpm range, and the other one in the higher range.