LOUISVILLE, Ky. — Navistar has announced four new performance ratings for its MaxxForce big bore diesel engines and a new MaxxForce Engine Brake by Jacobs.

The new ratings include two 450-hp MaxxForce 13 models – one that offers 1,700 lb.-ft. torque and another with multi-torque output of 1,550/1,700 lb.-ft. The other two new ratings include a 430 hp MaxxForce 13 with multi-torque output of 1,550/1,700 lb.-ft. and a MaxxForce 11 rated at 365 hp and 1,250 lb.-ft. torque. Top ratings remain at 475 hp and 1,700 lb.-ft. torque for MaxxForce 13 and 390 hp and 1,450 lb.-ft. torque for MaxxForce 11.

“For the Class 8 market, the name of the game is power,” said Jim Hebe, Navistar vice-president, North American sales operations.

Both the 11 and 13 models have also just received EPA certification for 2010 emissions, Hebe added.

The MaxxForce power and throttle characteristics stem in large part from their dual sequential turbocharger system. A smaller, primary turbo responds quickly for immediate take-off at low engine speeds, and a larger, secondary turbo provides peak power at higher speeds and on steep grades. Peak torque is achieved at 1,000 RPM and holds steady to 1,200 RPM – a much lower engine speed than other big bore engines. This reduces gear-shifting needs uphill and allows for shifting at lower speeds when accelerating.

A high-pressure, common-rail fuel system features injection pressures of 32,000 psi (2,200 bar) for fuel dosing, injection timing and combustion.

The optional MaxxForce Engine Brake by Jacobs provides a new level of braking power for the MaxxForce 11 and 13. Fully integrated with vehicle controls and anti-lock braking system (ABS), the three-stage, compression-release brake offers maximum downhill braking performance from 351 to 398 braking horsepower at 1,900 to 2,100 RPM for the MaxxForce 11. For the MaxxForce 13, maximum downhill braking performance is 415 to 470 braking horsepower at 1,900 to 2,100 RPM.

The new engine brake can increase service brake life of MaxxForce big bore-powered International ProStar+, PayStar, TranStar and WorkStar commercial trucks by up to three times, the company claims. The new MaxxForce Engine Brake by Jacobs also features:

• Dedicated cam compression release technology for maximizing braking performance
• Proven technology and durable, reliable operation
• Braking power equal to positive power
• Factory installed or dealer retrofit

The MaxxForce Engine Brake by Jacobs is comprised of two engine brake housings and special exhaust valve bridges. The engine control module (ECM) controls the engine brake and has three available braking levels, depending on driver needs. Integrated with the engine’s electronic controls and vehicle’s anti-lock braking system (ABS) for greater driver control, the brake is also fully functional with Allison transmissions.