Diesel Horsepower

[Wingnut]

Sorry, you guys lost me on that one ... in my mind, the piston (attached at one end to a crankshaft, nyet? .. has to travel the same distance nop matter what the RPM are ... ergo, if the RPMS are higher ... the distance travelled in a set period of time would have to be higher. Or did I misread all those manuals after all?

JimB ... the way to figure out the difference in actual HP between a gas and diesel engine ... well, find you get about 30 Begian horses and some heavy duty harnesses .....

too bad that common sense ain't

 

[90cummins]

There's another fundamental difference between a diesel and gasoline engine.
Gasoline engines are constant volume (some exceptions) Diesels are constant pressure.
Gasoline engines take in a fixed volume of fuel/air mixture and ignite it, combustion starts, pressure quickly peaks to maximum pressure then rapidly drops as the piston moves down the cylinder. (Constant volume).
This is why gasoline engines tend to stall out easier.
Diesels take in un-throttles air only (turbocharged diesels take in excess air) fuel is injected starting combustion the rapid increase in pressure (this causes the diesel knock) starts pushing the piston down and the fuel keeps injecting into the cylinder maintaining and/or increasing the combustion pressure (constant pressure). The half way point in the cylinder is the point of maximum mechanical advantage and the fuel is still being injected maintaining pressure (torque).
At some point after this the fuel injection event stops and pressure drops and the exhaust cycle begins.
Diesels maintain higher cylinder pressures longer than gasoline engines which makes them pull harder, longer and just refuse to stall.
HP = Speed x torque /5252
HP is HP how its delivered it the difference.
The amount of HP determines how fast you can go, Torque determines how much you can pull.
Hope this explains some of your questions.

90cummins