From news.com

Following announcements from EcoMotors and Transonic Combustion, San Diego’s Achates Power has said on its Web site that it’s creating a clean, light, fuel-efficient diesel engine.

The company has also received investments from Sequoia Capital, a relative newcomer to energy investments, Rockport Capital Partners and Interwest Partners. (VentureWire has a brief interview with Achates CEO James Lemke.)

Achates has not said how its engine will work, the company has three patent applications on file with the U.S. Patent Office. Two of the patents describe what’s known as an opposed piston/opposed cylinder engine. In this type of engine, two pistons sit inside a single cylinder. That makes it different than most other motors where pistons have individual cylinders. (Some car makers have made engines with horizontal pistons, similar to an opposed piston engine, but they have their own cylinders.)