New piston bowl, aftertreatment enhancements for DD15 engine

by Today's Trucking

Daimler has unveiled a series of enhancements to its Detroit DD15 engine, to be available in trucks beginning in January 2021.

The proprietary DD15 Gen 5 powerplant includes nearly 50% new componentry, boosting fuel efficiency by 3% and reducing carbon dioxide emissions in the process.

The DD15 Gen 5 engine is described as a perfect complement to the Freightliner Cascadia. (Photo: Daimler)

Improvements in the latest model year include increased downspeeding and enhanced combustion.

A reshaped piston bowl, combined with modified inlet ports in the engine cylinders, creates a swirl effect that better atomizes fuel. With a higher compression ratio, that improves combustion and efficiency.

A new ball bearing simple geometry turbocharger reduces friction and allows Cascadia trucks to reach peak power and torque more quickly, the OEM says. The peak horsepower is reached at 1,500 rpm versus the previous 1,625 rpm, while peak torque is reached at 900 rpm compared to the previous model’s 1,075 rpm.

The aftertreatment system is smaller in size, and 60 lb. lighter, but increases the conversion of nitrous oxide. Depending on the duty cycle, diesel particulate filter (DPF) service intervals can be increased as well, Daimler says.

This is also the first engine to include a new ThermoCoasting feature that will keep the aftertreatment system from cooling down during a driving regen. When needed, it will engage the engine brakes between 900 and 1,500 rpm, while the engine mimics coasting by maintaining zero torque at the flywheel to balance the delivery of power, the OEM explains.

Powertrain noise that exists during ThermoCoasting is described as “unobtrusive” and matching the noise of a low engine brake setting.

Other thermal management improvements include better cooling circuitry and temperature distribution across the cylinder heads.

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