Why are petrol engines more powerful than diesel engines for the same cubic capacity (displacement)?
Diesel engines are more efficient than gasoline (petrol) engines of the same power, resulting in lower fuel consumption. Diesel engines produce very little carbon monoxide as they burn the fuel in excess air even at full load, at which point the quantity of fuel injected per cycle is still about 50% lean of stoichiometric. The full load limit of a diesel engine in normal service is defined by the “black smoke limit”. Beyond which point the fuel cannot be completely combusted, as the “black smoke limit” is still considerably lean of stoichiometric. It is possible to obtain more power by exceeding it, but the resultant inefficient combustion means that the extra power comes at the price of reduced combustion efficiency, high fuel consumption and dense clouds of smoke. They are efficient, not powerful.
