Cummins, feds developing four-cylinder diesel for Nissan Titan

May 2011 News

Cummins is developing a high-efficiency inline-four-cylinder diesel engine with money from the U.S. Department of Energy and in partnership with Nissan for demonstration in the Titan light-duty pickup truck. The project was announced at the DOE's 2011 Merit Review in Washington, D.C..

Most half-ton truck makers are betting on small-displacement direct-injection gasoline engines to meet future fuel economy regulations, but Cummins expects its small displacement oil burner to get 40 percent better fuel economy over current light-duty V-8 truck engines. The Cummins average fuel economy target for this new diesel engine is 28 mpg while meeting tough U.S. Tier 2 Bin 2 emissions limits, according to the presentation.

Getting 28 mpg combined mileage could mean more than 30 mpg highway, by our estimate, which could help Nissan meet strong new EPA regulations that will raise fleet fuel efficiency standards for light trucks and SUVs to 30 mpg by 2016. The standard for passenger cars is set at 39 mpg by 2016.

Prototype Cummins four-cylinder inline diesel in a current Nissan Titan's engine bay.

Though the project started in September, Nissan and Cummins have already built a prototype version of the four-cylinder diesel and installed it in a current-generation Titan mule for drive testing. Pictures of the engine show four high-pressure fuel rails feeding the engine's cylinders.

Four cylinders might not seem like enough to power a full-size pickup but that architecture would be ideal to meet fuel economy goals while delivering almost as much torque as some small displacement gasoline V-8s.

Cummins refers to the engine by the codename "LA-4" with a 2.8-liter displacement (170 cubic inches). Initial power figures on the engine dyno have the mule test engine producing 350 pounds-feet of torque at around 1,800 rpm. A chart in the presentation shows targeted power levels to be approximately 220 horsepower and 380 pounds-feet.

The engine is likely a derivative of the four-cylinder ISF architecture that Cummins builds overseas, with 2.8-liter and 3.8-liter displacements. The overseas 3.8-liter is rated at 168 horsepower and 443 pounds-feet of torque.


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