Atkinson-Cycle 2.0-Liter 4-Cylinder Engine

What’s the Benefit?

When Honda engineers added leading-edge technology to an established engine design, they created an extremely fuel-efficient powerplant.

The Feature:

The Prelude engine makes for excellent efficiency, as well as responsive power output.

• Developed many decades ago, the original Atkinson-cycle engine improved fuel efficiency by reducing the volume of air and fuel introduced on the intake stroke and compressed on the compression stroke.
• This smaller intake charge would then burn more efficiently during ignition, while still providing adequate torque on the power stroke.
• For the Prelude, Honda engineers used the flexibility of Variable Timing Control (VTC) on both camshafts to simulate the original Atkinson-cycle principles, with operating efficiency that goes far beyond a traditional internal-combustion engine.
• Specifically, VTC delays the closing of the intake valves until much later than usual on the compression stroke.
• The resulting smaller volume of air/fuel mixture then burns more completely and efficiently during the power stroke.
• When needed, valve timing can be adjusted more like a conventional engine’s for greater power output.
• Bottom line, the 2.0-liter Atkinson-cycle 4-cylinder engine is like having two engines in one.