Last month's "How It Works" story gave you the basics of the four-stroke cycle, describing the motion of the intake and exhaust valves in relation to the piston moving up and down in the cylinder.

What makes a diesel engine different to a regular gas engine, and is one better than the other?

Air flowing into a four-stroke diesel engine gets cleaned as it passes through the air filter. It then flows through tubing until it is compressed in the spinning blades of the turbo. As a result, the ...