Quote:
Originally Posted by Tracus
HP is not measured by an instrument, is man made. A car’s performance is tested by measuring its torque by using a dynamometer. The measure of an engine’s performance is torque. Horsepower is an additional number that’s attained by multiplying the torque by the RPMs.
I know what you mean, you choose HP because your HP represent the total torque that gets delivered to the wheel (raw power plus RPM). Gearing magnifies torque and makes the difference.
So,
If the design objective is performance instead of low fuel consumption, the diesel engine can perform adequately.
BMW M550d xDrive 3.0 liter turbo diesel 6-cyl engine 0-60 mph in 4.7 sec.
BMW 535i xDrive 3.0 liter turbo 6-cyl gas 0-60 mph in 5.7 seconds.
See Audi winning LeMans with diesel please.
|
Gearing does magnify torque, and thus you will always have an advantage with a design that can have broad torque and still rev higher.
Diesel engines are turbocharged designs with relatively long stroke because they cannot really be revved very high. If you build a petrol engine with the same long stroke and turbocharging, you'll have something very similar, but it will probably be able to rev higher and thus generate more HP and the same torque.
Instead of thinking of diesel engines as torque monsters, you should think of them as horsepower or rotationally deficient. 382HP out of something that has that much peak crank torque is not something to be proud of.
Diesels are good for towing, fuel economy, and range. Not for outright performance at anything above very low RPM.