Compression ratio - the ratio between the volume of the cylinder with the piston in the bottom and top positions - is a fundamental parameter of engine design, playing a direct role in power and fuel efficiency. Compression ratio has traditionally been a fixed design point, but an innovative WinGD technology means that, for the first time in any marine engine, compression ratio is now adjustable.

Variable Compression Ratio (VCR) technology allows compression to be adapted to the fuel currently in use, improving fuel consumption and reducing emissions in each case. The technology means that operators do not need to compromise on efficiency with a fixed compression point, and new engine designs can also reflect this capability.

Compression ratio is altered by changing the piston position to adjust combustion chamber volume. The simple mechanical configuration has no impact on engine footprint or installation requirements. VCR can also be adjusted for part load operation, meaning that relatively larger savings can be achieved at the low speeds.

VCR is unique to WinGD and is set to become a core engine technology of the future. As emissions targets become more stringent and as the higher cost of new fuels demand an ever greater focus on efficiency, ship operators will increasingly seek compression without compromise.

VCR is made available for X72DF, X62DF and short-stroke X62DF-S engines. Further rollout of the technology to the remaining X-DF LNG engine portfolio is planned, with the next engine type becoming available for delivery from early 2026. WinGD will also develop and offer VCR retrofit kits for X-DF engines in service.