when you read:
"No electrical apparatus is required for ignition purposes. Ignition is accomplished by its own heat and compression; it runs about 800 revolutions per minute, has five cylinders and no fly-wheel is used. "
why do you jump to the conclusion that a (so-called) diesel engine is implied?
Yes, the description of the alleged engine, that equipped the No. 22 plane of Gustav Whitehead, can fit that of a hot tube or hot bulb engine (which are related to diesel motors). However, I can not find such engines, built around or before 1902, that have powers and weights approaching those claimed by Whitehead for his mysterious ignition by heat and compression power plant.
The only known engine of that time with a similar performance to Whitehead's motor was the Manly–Balzer engine (also with 5 cylinders) which used electric sparks for igniting the fuel not compression.
Dry weight: 136 lb (62 kg)
Power output: 52 hp (39 kW) at 950 rpm
Delivered: March 1903
see:
Manly?Balzer engine - Wikipedia, the free encyclopedia