For example, why does 5.7L V8 Tundra Engine make 381HP/401 pound-feet and a 2.3L 4Cyl Focus RS make 350HP when other V8’s can make ~700HP.
In: Engineering
The short and simple thermodynamics answer is that it is at a lower pressure as it sweeps out its volume. Energy is pressure times volume. Either that, or it completes cycles faster, as power is energy over time.
In real engines this gets a bit more complicated.
For one, there are losses in the engine – wasted energy such as friction which can play a role. A very wide engine will have more efficiency than a comparable-volume engine with a very long stroke.
On top of that, pressure varies a lot in an engine. It starts low as the engine sucks air in, then rises as the piston comes down, then spikes at ignition and drops as the piston rises. It then drops as the valve opens, and rises a bit as exhaust is forced out. Hotter fuel-air mixes raise the pressure more. The duration of the burn changes the pressure curve. The heat of the air changes it. When fuel injection and ignition take place change it. Combustion efficiency changes it. There are a lot of variables involved.
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