
To put a little bit of explanation, diesel engines are highly compressed (not to even mentioned a tune one), a petrol engine would typically compressed air up to 1/10th of its original mass, whereas a diesel engine does 1/22nd of its initial mass, the high compression means diesel engine need no spark plugs to ignite the fuel and air mixture as in petrol engines, whereas diesel engine's ignite the fuel by the hot, compressed air itself. This literally means a diesel engine could in fact run without electricity (if not for the modern sensory or solenoid stuffs).