GM's Duramax V-8 engine to power U.S. Army's Humvee replacement

Editor's note: The Duramax engine's basic OHV layout with four valves per-cylinder has remained unchanged since 2001. An earlier version of this story contained an inaccurate description of the engine. 

General Motors’ powertrain division will be supplying the engine for the successor to the Army’s Humvee -- a deal that could see GM deliver as many as 55,000 diesel V-8 engines.

The new Joint Light Tactical Vehicle, to be built by Wisconsin-based Oshkosh Defense LLC, will be powered by a military specification version of the Duramax turbodiesel V-8 used in GM’s heavy-duty pickups. It will also use a transmission made by Allison Transmission LLC, a company formerly owned by GM.

Jennifer Christiansen, vice president of business development operations for Oshkosh, said the company evaluated several engines before choosing the Duramax V-8.

The 6.6-liter Duramax engine, jointly developed and built with Isuzu, has been a workhorse for GM since 2001, powering most heavy-duty versions of the Silverado and Sierra pickups. The civilian version of the engine is rated at 397 hp and 765 pound-feet of torque.

A GM spokesperson was not immediately available for comment.

GM has revamped the turbocharged Duramax engine several times since 2001, but its basic OHV layout with four valves per-cylinder -- has remained unchanged. The company has built more than 1.5 million of the engines.

The Humvee that is being replaced is powered by a GM-designed diesel engine which dates back to the 1980s.

Oshkosh does not list any specifications for the military version of the Duramax engine, but says that it will offer improved fuel economy when idling and driving.

The contract pays for 17,000 JLTVs, but it could eventually be worth $50 billion and nearly 55,000 vehicles, The Washington Post reported. The JLTV will be used by the Army and the Marines. GM will build the JLTV’s engine in its Duramax engine plant in Moraine, Ohio.

The JLTV will be assembled in Oshkosh, Wis.

Oshkosh beat out Lockheed Martin and AM General for the contract.