The world of automotive engineering is filled with innovation and experimentation, leading to some rather unusual engine designs that made it to production, albeit briefly. These engines often broke ...

Converting the ignition of a fuel-air mixture into usable mechanical energy lies at the core of a dizzying number of internal combustion engines developed over the course of more than century.

The plastic cover of a Subaru Boxer engine showing the Subaru constellation logo - Topuria Design/Shutterstock Flat engines are horizontally-opposed piston engines, and this group includes Boxer ...

An opposed-piston free-piston engine is essentially two single-piston free-piston engines that have their pistons coupled together through a linkage. Like a more typical opposed-piston engine, an ...

Flat engines are horizontally-opposed piston engines, and this group includes Boxer engines, but not opposed-piston engines like the Cummins 14.3L Advanced Combat Engine (ACE) designed to power tanks.