Diesel engines, for all their rugged usefulness, can be tremendously polluting. They produce more NOx — nitrogen oxides-based emissions – than gasoline-fed cars, as well as more particulates, aka soot ...

Almost all gasoline engines, whether they're efficient-yet-less-refined four-cylinders, high-horsepower V6s, or growly and torque-rich V8s, use much the same process to create power. The "Otto cycle" ...

Harbor Freight sells two versions of its Predator 212 engine with differing horsepower outputs. Both are four-stroke designs featuring horizontal crankshafts, recoil pull-start, and 212cc ...

The story of how Honda developed an oval-piston race engine that ultimately failed but still made history along the way. Honda pioneered oval piston technology in the 1970s for four-stroke racing ...