The MCE-5 engine from MCE-5 Development in Lyon, France (www.mce-5.com), varies its compression ratio and uses a combined gear and rod-crank mechanism. Varying compression from 7:1 to 20:1 makes the engine more efficient than current gas engines. The engine can be adapted to use any shape for the combustion chambers and cylinder heads.

Piston motion remains the same, with the same rod-to-crank ratio regardless of compression ratio. Hydraulic actuators precisely control the compression ratio for each cylinder. And the crank, which is half the size and more rigid than those in conventional engines, provides a stiff and precise bearing line and an optimum setup for moving parts. The rollerguided pistons are not subject to rod thrust or piston slap, and they carry the forces generating torque on the crankshaft. This reduces friction losses and extends cylinder life. All components are enclosed in the engine block with no moving parts visible. And it mounts inside vehicles just like conventional engines. Connections to the gearbox, pipes, and peripherals are also the same as in current engines.

Maximum torque is at about 2,000 rpm or lower, while maximum power speed is at 5,500 rpm or higher, and limit speed is approximately 7,000 rpm. It reportedly reduces fuel consumption by 20% versus same-sized conventional engines. If development continues on pace, an MCE-5-type engine could produce the fuel efficiency and reduced emissions of a hybrid by 2010 and cost $3,000 less.