Originally Posted by
Bush65
No typo in whatever reference you took the crossing rpm from. Dougal didn't dispute that, he was making the point that where the torque and power curves cross is a consequence of the units of measure used and not to read anything else into the coincident.
I see some still think that 700Nm might be believable/achievable. My earlier post pointed out that If the power was as stated, then the torque was in error, or if torque was as stated them power was in error. Perhaps those people couldn't see that connection for some reason!
Engine dynos, measure torque over a range of rpm, then calculate power from those values. Chassis dynos do much the same, but the problem is the reduction in the gearing increases the torque (measured at the tyre tread), and there are losses between the engine and tyres. When the measured/calculated values are referred back to the engine, the results are open to error.
A diesel engine produces a torque vs rpm curve that has a shape that will somewhat follow the shape of a curve of volumetric efficiency vs rpm of the engine, i.e. the peak torque very nearly occurring where VE is greatest and falling at high rpm as VE drops. Power still increases as torque drops while rpm increases.
When performance of diesels is increased, the torque curve is similar just moved up. So if the torque was increased to 700Nm, it should still be at nearly the same rpm, and the shape should be similar. Then for 700Nm torque the power would have to be much greater than quoted, unless the torque dropped dramatically (unrealistic) from the rpm where it peaked.