A new spin on the internal combustion engine by startup LiquidPiston aims for a leap in efficiency from 20 percent to 50 percent.

If someone tells you they have seen a rotary engine, the chances are that you will immediately think of a Wankel engine, as you might find in some of the more exotic Mazda sports cars. But there is… ...

Despite the rotary’s flaws, one American startup tried to argue the Wankel’s case—not in cars, but by bringing it to the waves in 11.6-liter, diesel-burning big-block form.