Today is Happy Birthday to the Diesel engine........

[Sojourner]

Today is birthday of the internal combustion engine without sparkplug in 1893.
Inventor Rudolf Diesel, 1858-1913

http://inventors.about.com/library/inventors/bldiesel.htm

As I said in past posts....it take in the area of 700ºF with atomize vapor to ignite most combustibles fuel. Via compress (stroke) air till it reach combustion temperature.

Cranking RPM is important factor as well compression seal (rings, piston, cylinder or liner, cylinder head, valves, O-ring & gasket), injector or carburetor and cam shaft (valve timing).
Another word slow cranking (diesel) equal low combustion (ignition) temperature (less than 690ºF) and the colder the air & engine temperature the greater the cranking RPM to achieve high enough compression pressure to establish around 700ºF for ignition.

So for better fuel economy...maintains engine temperature at highest manufacture specification to accomplish greatest combustion power for given fuel. And good cranking system to start in most climates.

FWIW

Sojourn for Christ, Jerry

[Dreamscape]

Now I know who to thank for this love of the smell of diesel! 

Very interesting information, Thanks Jerry.

By the way I really like the way you sign off, very refreshing in this day and time of this world.

Paul