The Detroit Diesel Series 71 is a two-stroke cycle diesel engine series, available in both inline (the company's initial available engine configuration) and V (introduced in 1957) configurations, with the inline types ranging from one to six cylinders and the V types ranging from six to 24 cylinders. It was introduced as the initial flagship product of the Detroit Diesel Engine Division of General Motors in the division's 1938 founding.
The 71 series engines utilized uniflow scavenging, where a Roots blower mounted to the exterior of the engine providing air at greater than cylinder pressure (positive displacement), and exhausted through two or four exhaust valves per cylinder. The supercharger was used to provide positive displacement, required for a two stroke cycle, instead of using the crankcase as commonly used on small high speed gasoline motors. Later high performance versions were available with turbochargers, and turbochargers with aftercooling.
The most popular incarnations of the Series 71 diesel as used for highway vehicle applications included the inline 6-71 and the V-block 8V-71 (the latter of which was introduced for sale in 1957). Both incarnations had found their way in many popular applications including trucks, heavy-duty buses, motor homes, construction and industrial equipment, and military applications.
The inline 6-71 engine, in all of its variations, was also available as a 'pancake engine' (here invariably called either 6L-71 or 6N-71) for horizontal (underfloor) mount applications, such as on larger Crown and Gillig school buses and articulated puller transit buses (such as the Ikarus 286).
- 71 cubic inches (1.2 liters) per cylinder.
- 1.2L (1-71/Single cylinder) 2.3L (2-71/I-2), 3.5L (3-71/I-3), 4.7L (4-71/I-4), 7.0L (6-71/I-6 and 6V-71/V-6), 9.3L (8V-71/V-8), 14.0L (12V-71/V-12), 18.6L (16V-71/V-16) and 24.1L (24V-71/V-24)
- Power ratings ranging from 15 to 1100 HP
- 6-71 (inline; turbocharged variation) supported the DDEC I, II and III.
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