The lightweight engine is based on a supercharged, two-stroke, diesel opposed piston architecture with Scotch Yoke crankshaft and a central injector position.
Ricardo said the engine topology "promises a power-to-weight ratio comparable with high-performance gasoline engines, while delivering diesel fuel consumption and a package volume around half that of a state-of-the-art diesel engine."
Ricardo is undertaking work in the prototype development stage of the engine under a Ministry of Defense contract.
The engine is intended for marine outboard applications on the navy's rigid inflatable boats.
"Ricardo is proud to be assisting with the development of the Cox Powertrain engine and with the development of the company in terms of best practice engineering processes and design and development capabilities," said Ricardo UK Managing Director Martin Fausset.
"While Ricardo's reputation in the field of high-performance, lightweight engine design is globally renowned, the company also has an extremely strong track record in the successful delivery of advanced defense programs and in assisting small, high-technology start-up partners to achieve their full potential."
Cox Powertrain approached Ricardo at an early stage to provide assistance in developing the Cox engine concept and in supporting the growth of the small start-up operation.