Detroit Diesel Series 50

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Detroit Diesel Series 50
Manufacturer Detroit Diesel (cylinder heads cast by John Deere)
Also called Series 50, Series 50 EGR, Series 50G, Series 50 MK-G
Production 1994-2005 (currently still available for off-road vehicles)
Configuration Straight-four diesel engine
Displacement 8.5 litres
Piston stroke 4 stroke
Cylinder block alloy Cast iron
Cylinder head alloy Cast iron
Turbocharger Variable geometry turbocharger
Fuel type Diesel, CNG, LNG
Predecessor Series 60
Successor Daimler Heavy-Duty Engine Platform (Series 13, 15 & 16) [1]

The Detroit Diesel Series 50 is an inline four-cylinder diesel engine, that was introduced in 1993 by Detroit Diesel. The Series 50 was developed from the existing block of its sister engine, the Series 60, which itself was initially designed by Detroit Diesel. The cylinder heads were cast by John Deere at one time.

The Series 50 engine is used as a major bus engine in North America, especially from buses built in the mid to late 1990s and early 2000s. The power plant is offered for several applications: trucks, buses, motor homes, construction and industrial equipment, and military vehicles. It is unusual to find an inline four-cylinder engine propelling heavy duty buses, which traditionally use inline six, V-6 or V-8 diesel engines.

In 2000, in order to better respond to the tougher EPA emissions standards, Detroit Diesel announced revisions of the Series 50 for diesel applications. The changes included the addition of an exhaust gas recirculation (EGR) system, and a variable geometry turbocharger system to improve torque.

In addition to being powered by diesel fuel, the engine can also use alternative fuels such as compressed natural gas (CNG) or liquified natural gas (LNG) under the Series 50G label. Several thousand Series 50 propelled buses are now on the streets of major cities such as New York City and Philadelphia. In September 2004, Detroit Diesel ceased production of the Series 50 heavy duty diesel engine for on highway applications due to emissions standards. It is still available for off-road applications. A replacement was scheduled to take place in 2007, then was pushed back until 2009. According to Detroit Diesel, Series 50 engines will no longer be produced for non-Daimler AG trucks or buses beginning in 2010.


  • Power ratings ranging from 250 to 350 [horsepower] (186 to 260 kW)
  • Supports the DDECIII and DDECIV
  • Since 2001 the engines included an EGR device.
  • Twin balance shafts
  • Single over head camshaft design
  • Electronic Unit Injection

Popular horsepower ratings[edit]

  • 725 ft·lbf (983 N·m) @ 1200 rpm, 250 hp govern at 2100 rpm
  • 890 ft·lbf (1,210 N·m) @ 1200 rpm, 275 hp govern at 2100 rpm
  • 1,150 ft·lbf (1,560 N·m) @ 1200 rpm, 320 hp govern at 2100 rpm[2]

Competing power plants[edit]


  • Detroit Diesel Series 50 Engine 300-350 HP Fire Equipment. Detroit Diesel. 2000. p. (Sales brochure). 
  • Diesel Engines Series 50&60 for Petroleum Applications. Detroit Diesel. 2003. p. (Sales brochure).