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78.0L Colossal Cummins Engine

3,500 hp And 10,157 lb-ft Of Torque

Mike McGlothlin
Jun 1, 2010
Photographers: Courtesy of Cummins
Bigger is always better. And the QSK78 from Cummins is just that-a bigger and badder version of its QSK60 currently powering hundreds of off-highway trucks around the world. The engine, a V-18 designed and developed by the Industrial Power Alliance (IPA) technical joint venture between Cummins and Komatsu, is intended for haul and mine trucks with 320- to 400-ton payload capacities. Some applications currently being powered by Cummins' QSK78 are: Liebherr T282B (360-ton payload), BelAz 7560 Series (320-ton payload), and Komatsu's 960E-1 (360-ton payload).
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Engine
Built alongside the QSK60 in the United Kingdom, the QSK78 consists of a one-piece, cast-iron block with a bore of 6.69 inches, a stroke of 7.48 inches, and a displacement of 4,735 ci (77.6L). The block also utilizes wide cylinder spacing, which allows for multiple, full-life engine overhauls and improved coolant flow. The cast-iron cylinder heads incorporate seven bolts per cylinder and feature four valves per cylinder. An electronic Quantum high-pressure injection (HPI) fuel system offers high peak injection pressures for performance while providing optimum fuel economy and lower emissions. Rated for 3,500 hp at 1,900 rpm, the QSK78 also makes 10,157 lb-ft of torque at 1,500 rpm.
Oil And Coolant
A Cummins Eliminator full-flow, bypass oil filtration system is a combination of a serviceable stainless-steel element and an oil pressure-powered centrifuge housed in a single unit bolted directly to the engine block. This system is standard on the QSK78 and allows the engine to operate 1,000 hours or more between oil changes. Its cooling system consists of two separate water pumps and radiators. The engine cooling loop runs at a higher temperature for efficient engine operation and utilizes an engine radiator. The low-temperature aftercooling (LTA) loop operates at lower temperatures to cool the compressed intake air from the turbochargers and uses a radiator to control the low-temperature aftercooling loop.
Two-Stage Turbocharging
In order to keep this massive engine efficient at any elevation, a two-stage turbocharger system is used. This design allows the engine to remain powerful and gives it an altitude capability of more than 16,000 feet without reducing the engine's power. Six (yep, six) HX82 Holset turbochargers take care of the low-pressure stage, routing compressed air through an intercooler. From there, six HX60 Holset chargers serve as the high-pressure units and force the compressed air through an aftercooler and into the combustion chamber. The coolest air possible entering the engine offers unmatched reliability and cooling. All turbochargers utilize water-cooled bearing housings as well.
1. The cast-iron cylinder block uses pressed-in, top-stop cylinder liners for increased reliability.
2. The crankshaft is made from forged, high-tensile steel and features a large, 20.4-inch-diameter dual-viscous damper for reduced geartrain wear.
3. The oil system holds 76 gallons (304 quarts) of oil. The cooling system holds 59 gallons (236 quarts) of coolant. The wet engine weight is 24,912 pounds.
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4. Two-stage turbocharging allows optimum high-altitude efficiency up to 16,400 feet and provides eight times the atmospheric pressure capability.
5. Aftercooling is utilized for the coolest air possible entering the engine.
6. Extended Service Centinel Oil Management is an electronically controlled, continuous oil replacement system that automatically replaces lube oil depending on engine load.

Sources

Cummins Inc.
Columbus, IN 47201
812-377-5000
www.cummins.com
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