Opposed pistons share a combustion chamber in this venerable engine design, and Achates's refined version claims fuel-economy improvements.

The opposed-piston motor has been around for almost 100 years, but it's never been put into a land vehicle before, until now. Here's what you need to know.

I’m talking about the opposed-piston engine. Opposed-piston engines have been around since the late-19th century, so the idea isn’t new.

Instead of one piston per cylinder, which requires four cycles per firing, opposed-pistons engines have two pistons per cylinder, both connected by levers with a single crankshaft.

Posted: May 22, 2025 | Last updated: May 31, 2025 Can Opposed Piston Diesel Engines Save The Combustion Engine?

An opposed-piston engine replaces the cylinder head with another set of pistons, each sharing a common cylinder, like a boxer engine but with no heads.

In this video, I take on an exciting engineering challenge: combining two internal combustion engines into a single opposed-piston engine. This unique project improves balance, reduces vibrations, and ...

An opposed-piston engine is a two-stroke engine with separate oil flow. It has no cylinder heads and no valves, both sources of considerable loss of heat and power in conventional combustion engines.

Achates Power reports that tests on its latest opposed-piston engine design meet 2027 emissions requirements of both the U.S. EPA and California.

While the vast majority of engines have used the same piston and cylinder design for decades, there have been exceptions like the Commer Knocker.

An opposed-piston engine packages two pistons in each cylinder and produces more power density than a conventional single-piston-per-cylinder engine.