Quick questions on Internal combustion engines: HSC Engineering Studies Personal and Public Transport

The four-stroke petrol engine cycle uses two crankshaft revolutions per cylinder per cycle:

A two-stroke engine completes a cycle in one crankshaft revolution. The intake and compression occur simultaneously (compression on top of the piston, intake below it), and the power and exhaust occur together. Two-stroke engines have more power strokes per revolution (so more power per litre of displacement) but burn oil with fuel, emit more pollution, and are now used mostly in chainsaws, small outboards and some motorcycles.

Power from torque and rotational speed:

The Holden Commodore (1978-2017) used Australian-made petrol V6 and V8 engines. The Ford Falcon (1960-2016) was a parallel programme. Both ended local manufacturing in 2016-2017. Australian-market vehicles now use imported powertrains from Japan, Thailand, Korea, Germany and the United States.

Power in watts requires $\omega$ in radians per second. $\omega = 2 \pi N / 60$ for $N$ in rpm.

In a petrol engine, the spark ignites the mixture at the end of compression. Compression alone is not enough. In a diesel engine, the higher compression ratio raises the air temperature above the fuel autoignition temperature, and combustion starts when fuel is injected without a spark.

The four-stroke petrol cycle is the Otto cycle. The four-stroke diesel is the diesel cycle. Both are real four-stroke engines but differ in how heat is added.