LAS VEGAS -- As promised, Navistar has finally launched its long-awaited MaxxForce 15 for use in severe-service trucking.

The 15-liter, big-bore powerplant, which rounds out a trio of engines that includes the MaxxForce 11 and MaxxForce 13, comes wrapped in the International PayStar 5900 set-back-axle tractor.

(You can also get the engine in a PayStar 5900 set-forward-axle version.)

The MaxxForce 15 is available with up to 550 horsepower and 1,850 lb.-ft. of torque and is the most powerful engine Navistar builds. And it’s designed to be tough, the company says.

Durability is assured with a four-bolt connecting-rod design that assures the clamping force and rigidity required for extreme loads and terrain.

The only North American engine to employ Advanced EGR (as opposed to SCR) as a means of meeting 2010 emissions standards, peak-performance torque for the MaxxForce 15 is achieved at 1,000 rpm and holds steady to 1,600 rpm.

To this point, Navistar has been marketing the MaxxForce 13 as its big bore option.

The MaxxForces are the platform for Cat's re-branded CT11 or CT13, and eventually the CT15.

"With the introduction of our MaxxForce 15, our line-up of fully-integrated trucks and engines is complete," said Jim Hebe, Navistar senior vice president, North American sales operations.

"The introduction of PayStar and MaxxForce 15 now gives us a proprietary truck and engine combination with the durability and power that heavy-duty construction customers demand."

The engine and truck were trotted out in Las Vegas at the annual CONEXPO/CON-AGG construction industry trade show.

Also on display at the show is the International PayStar 5600, which along with the PayStar 5500 is available with the MaxxForce 11.