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.

Trying to mix gasoline and diesel in most engines will only lead to problems in the long run. But engineers have found a way ...

Inside a diesel engine's cylinder, compressed air raises the temperature to ignite injected fuel, and the resulting force drives pistons to power the vehicle's main gears. Chief to this combustion ...