Technology Recycling

TECHNOLOGY RECYCLING

What do you do with 40 years of two-stroke R&D if the world goes four-stroke? You apply that knowledge to a clean, fuel-efficient, trendy diesel engine. This is what Yamaha has done to create its 1-liter SD diesel Twin. Because the engine is a crankcase-scavenged two-stroke, all those years of Grand Prix transfer-port design have immediate application. Having already developed High-Pressure Direct Injection (HPDI) for spark-ignition outboard motors, Yamaha will be no stranger to the problems of electronically controlled injection and spray formation. To improve midrange torque, a device reminiscent of the Yamaha Power-valve (as used on the 1984-85 RZ350) is featured. The pistons are reportedly cooled via novel materials and techniques. These technologies add up to a light, economical engine for a 1750-pound economy automobile. The Yamaha SD engine is said to meet upcoming Euro-4 emissions standards and has passed a 250-hour full-power test. Fuel mileage in the small-car application is said to be close to 80 mpg. Kevin Cameron