The new Caterpillar CT15 engine joins the CT11 and CT13 as the third engine option for the Cat CT660 vocational truck. Ratings go as high as 550 hp and 1850 lb ft of torque. It’s now available for order, with delivery during the first week of June.

The CT15 is based on a proven Caterpillar block and crankshaft with billions of miles of operation in demanding truck applications, the company notes. Its dual sequential turbochargers and high-pressure common-rail fuel system enable the CT15 to reach peak torque at 2100 rpm. Interstage cooling between turbochargers increases air density to maintain power as speeds increase.

The CT15 also offers an engine brake rated at more than 600 hp.

Like the CT11 and CT13, and like the International engines it’s based on, it features an advanced EGR system that reduces NOx in-cylinder without requiring diesel exhaust fluid (DEF).

The CT15’s single electronic control module and relatively few electrical connections are said to enhance reliability and reduce diagnostic and maintenance time. The high-quality, foam-molded wiring harness secures wires and connections, Cat says, and internally, the “premium” cam and rolling element valve train reduce friction and operational loads.