First and foremost, this is not a question about reparing or maintenance.
I'm familiar with how both petrol and diesel engines work, and I have a question about (possibly) making petrol engines more efficient?
In diesel engines, the fuel is ignited by compressing the air in the cylinder up to the point, where the temperature is high enough that combustion can occur by then "simply" injecting fuel in to the cylinder.
Would it be possible, to engineer an engine so that it can run on petrol with a spark plug, until it's at its operating temp, and then switching over to compression ignition?
I'd imagine it would be possible with either extremely high-octane fuel and/or variable compression? Maybe with an oil-driven solenoid in the conn rod? If it's possible (without completely re-thinking IC engines), has it been considered before? Possibly even done before? I'm no expert, but it seems at least possible.