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Mack Trucks MP 8: Compounded Efficiency

Performance and Fuel-Conscious Internal Upgrades Highlight Mack’s Versatile 13.0L Workhorse

John Lehenbauer
Jan 30, 2017
Photographers: Courtesy of Manufacturer
For more than 100 years, Mack Trucks has earned a reputation for building durable, powerful, reliable heavy-duty trucks and engines. Mack’s trucks are renowned for their abilities, which was partially solidified during World War I. British soldiers revered the Mack as having the “tenacity of a Bulldog” for handling the toughest jobs in the worst conditions. The praise of the Bulldog (a national icon of Great Britain) stuck with Mack’s philosophy and eventually became the trademark symbol that adorns its trucks.
Mack has never wavered from the ideal of building tough and dependable products. This is evident in such modern engines as the 13.0L MP8, a 24-valve, I-6 powerplant that has been a stable workhorse in the MP engine series for more than 10 years. Never settling, Mack bestowed upon its 2017 MP8 several upgrades and enhancements that simplify maintenance and improve power, fuel efficiency, and productivity. The advancements also reduce greenhouse-gas emissions. The enhancements include new, higher-compression, one-piece-steel, wave-design pistons; electronic unit injectors that incorporate both injection pump and nozzle; and a two-speed water pump.
Photo 2/3   |   The Mack MP8 is a Class 8, heavy-duty truck engine that is available in three configurations for different applications: MaxiCruise, Maxidyne, and Econodyne with EconoBoost.
Using fewer components helps increase the MP8’s reliability. Internally, a single overhead camshaft is paired with three shimless rockers, reducing internal stresses and creating a more simplified valvetrain. One-piece pistons and a one-piece cylinder head also alleviate pressure on the rotating assembly. Externally, the use of unit injectors instead of a complex common-rail fueling system eliminates the need for an independent injection pump and its associated high-pressure lines. Overall, it’s a significant reduction in weight, as the previous-generation MP8 weighed approximately 2,676 pounds, while the new engine comes in around 2,560 pounds.
The MP8’s improved fuel burn is credited to its exhaust-gas recirculation system, diesel oxidation catalyst, and diesel-particulate filter. The water-cooled EGR is updated with a double-walled flow sensor that reduces condensation and soot buildup in cold weather. To further reduce emissions during cold weather start-ups, a new throttle that promotes faster warm-ups is used.
Because maximum performance and peak efficiency are important in different truck applications, Mack offers the MP8 in three grades: MaxiCruise, Maxidyne, and Econodyne with EconoBoost. The MaxiCruise and Maxidyne engines use an electronically controlled variable-geometry turbocharger to control boost at all rpm ranges and loads. MaxiCruise is engineered for driving across rolling interstate, as well as on- and off-road use, where the emphasis is put on maximum torque. Maxidyne provides more horsepower for low-speed, severe-duty, off-road employment. The Econodyne with EconoBoost engines are geared toward long-haul trucking applications, for which fuel economy is of the utmost importance. Mack’s EconoBoost system uses intelligent torque management and compound turbocharging to increase power and efficiency. The system can provide an additional 200 lb-ft of torque (1,660 lb-ft compared to 1,460 lb-ft) at engine speeds as low as 900 rpm for as long as it is needed. The broader operating range in top gear allows for the gear to be held longer when pulling grades or passing. This ability to maintain lower engine rpm helps increase fuel efficiency by up to 8.8 percent. EconoBoost also generates more than 90 percent of the engine’s power after an upshift is made, eliminating turbo lag.
Photo 3/3   |   This is Mack Trucks’ updated MP8 engine. The powerplant features an electronically controlled variable-geometry turbocharger that regulates boost at all rpm ranges and engine loads. Econodyne with EconoBoost is available for interstate truck applications. The Econoboost system uses intelligent torque management and compound turbochargers to provide an additional 200 lb-ft of torque and a near 8.8 percent increase in fuel efficiency over single-turbocharged rigs.

SPECIFICATIONS

Engine: Mack MP8
Displacement: 13.0L (793.3ci)
Engine Layout: I-6
Valvetrain: SOHC, 24-valve
Bore x Stroke: 5.16 x 6.22 inches (131 x 158mm)
Compression Ratio: 16:1
Head material: Gray cast iron
Block material: Gray cast iron
Piston material: Steel
Power: 505 hp
Torque: 1,860 lb-ft
Induction: Variable-geometry turbocharger
Exhaust: Cast-iron manifold
Intercooler: Air-to-air
Cooling System: Liquid cooled
Fuel System: High-pressure common-rail with unit injectors
Lubrication System: Full-pressure wet sump
Lubrication Capacity: 33 quarts
Dry Weight: 2,597 pounds
Length: 56.7 inches
Width: 32 inches
Height: 49.3 inches

Sources

Mack Trucks
macktrucks.com
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