An opposed-piston engine that forms an inviscid layer between pistons and the respective cylinder walls. In an aspect, the opposed-piston engine utilizes a Scotch yoke assembly that includes rigidly connected opposed combustion pistons. In an aspect, the Scotch yoke assembly is configured to transfer power from the combustion pistons to a crankshaft assembly. In an aspect, the crankshaft assembly can be configured to have dual flywheels that are internal to the engine, and can be configured to assist with an exhaust system, a detonation system, and/or a lubrication system.