What is the formula to calculate engine power per cylinder in a diesel engine?

Answer 1

DETERMINING THE HORSE POWER OF AN ENGINE.

Multiply the area of the cylinder by the length of stroke in inches and that product by the number of revolutions per minute then divide by the constant 10000 for two-cycle or 13400 for four-cycle engine, the result will be the I.H.P.

EXAMPLE

Four-cycle engine, 4" bore, 4" stroke, 1000 revolutions per minute, constant 13400.

Then: 4" bore equals 12.56 area, then 12.56 x 4 equals 50.24 x 1000 equals 50240 divided by 13400 equals 3¾ I.H.P. for one cylinder, then to find the combined H.P. for multi- cylinder engine, multiply by the number of cylinders.

This is a very nice answer but it's not even close to correct. In order to find indicated HP, you need to have the Mean pressure in the cylinder. Not sure where the constants of 10,000 and 13,400 came from, but a 2 cycle has twice the HP of a 4 for the same pressure.

Real formula is Pressure times Length of stroke times area of piston times # of power strokes per minute divided by 33,000. This is the English HP. The world is switching over to Kilowatts, and the metric HP is a somewhat different formula.