A system and method for providing a variable compression ratio internal combustion engine is disclosed. The system can include a frame affixed to the engine crankcase and a complementary frame affixed to the block/cylinder head assembly. The system can further comprise an actuating system to enable the block/head assembly to be moved up and down with respect to the crankcase, varying the compression ratio of the engine. A number of mechanisms can be used to achieve this movement, including a rack and pinion, a hydraulic or pneumatic actuator, and a gear drive. The compression ratio can be varied continuously during use. The frames substantially limit movement of the engine components to the y-axis, thus reducing, or eliminating, unwanted movement and stresses in other directions.