Cummins Inc. debuted two new engines in the North American agricultural market at the World Ag Expo: the QSG12 and the QSF3.8. Both engines meet Tier 4 Final emissions regulations.
The 6-cylinder, 12-liter QSG12 provides up to 512 hp output for heavy-duty applications. The engine features a wastegated turbocharger and achieves near-zero emissions without the need for a cooled Exhaust Gas Recirculation (EGR) system.
The QSG12 achieves a low engine weight of 1,900 lb to enable a top-rated power-to-weight ratio of 0.27 hp per lb while retaining structural strength and durability.
The engine incorporates Cummins Xtra-High Pressure Injection (XPI) fuel system, derived from the QSX15 Tier 4 Final/Stage IV engine. The XPI fuel system contributes to a peak of 1700 lb-ft, with a torque rise as high as 60 percent available. XPI lowers noise and vibration and smoothes power delivery. The use of a rear gear train also contributes to overall engine refinement by reducing vibration and lowering noise by at least 1 dBA.
The QSG12 is a fully integrated air intake-to-exhaust aftertreatment package, ready for drop-in machine integration. The aftertreatment combines a Diesel Particulate Filter (DPF) with Selective Catalytic Reduction (SCR) to achieve an ultra-clean exhaust. The DPF operates as a near-passive device, with automatic active regeneration occurring less than 1 percent of engine running time. The use of a DPF in the exhaust stream provides the QSG12 with an additional margin of Particulate Matter (PM) emissions control at higher engine loads.
Cummins DPF-SCR aftertreatment system is able to withstand severe shock loads and vibration, and is designed with durability equivalent to that of the engine. The QSG12 features an integrated Cummins Direct Flow air filtration system developed for Tier 4/Stage IV applications. The direct flow air filter provides greater dust-holding capacity in a smaller package and features an embedded smart sensor to fully integrate air-intake flow with the engine combustion.
A two-stage fuel filter system for the QSG12 features NanoNet media from Cummins Filtration, to ensure that the XPI fuel injection system is fully protected against fuel contaminated with hard particles. The engine is specially configured with machine-adaptive features to facilitate machine integration across a range of applications.
The 3.8-liter QSF3.8 meets near-zero emissions standards with an SCR-only aftertreatment system. With PM reduction focused in-cylinder, the QSF3.8 avoids the need for either a Diesel Oxidation Catalyst or a DPF.
The SCR-only system features an extra-high-efficiency catalyst able to convert oxides of nitrogen emissions at lower exhaust temperatures while requiring only low-dosing levels of AdBlue/Diesel Exhaust Fluid.
The aftertreatment also reduces the amount of cooled exhaust gas being recirculated by the engine, with a corresponding reduction in engine loading and cooling demand. Peak torque of 360 lb-ft is delivered by Cummins wastegated turbocharger used for all QSF3.8 ratings.
The QSF3.8 achieves fuel efficiency similar to that of the 3.3-liter engine while providing 10 percent higher power output and increasing peak torque by 18 percent. It is equivalent in size and weight to the current QSB3.3, providing an easier transition from Tier 4 Interim to Tier 4 Final for compact equipment installations.
The QSF3.8 features a rear gear train, providing mounting stiffness and lower gear noise. The cast-iron block has a sculptured design, allowing unnecessary weight to be removed while retaining maximum rigidity. The use of composite material for the valve cover and oil pan brings a further weight reduction.
The engine is suited to the high-hour duty cycles of the rental equipment market. Servicing is made simpler through remote mounting of the Electronic Control Module, for plug-in diagnostics and data downloads. The oil fill, lube filter and fuel filter are set up for rapid service, with 500-hour intervals.
The QSF3.8 features the Cummins Direct Flow air filtration system and has a filter element change interval at least twice that of a conventional air filter. The filter also features an embedded smart sensor to fully integrate air-intake flow with the engine combustion.
The engine is equipped with a robust High Pressure Common Rail fuel system driven by Cummins full-authority electronic controls.
The QSF3.8 crankcase ventilation system eliminates blowby gas emissions to provide an ultra-clean engine. The system has a patented design, integrated into the camshaft, with no service requirements.
The engine lubricating pump is driven by the crankshaft rather than driven by gear from the camshaft. Noise is reduced, and oil flow is improved during cold starts. A compact cooling module on the engine brings together the water pump, oil filter and oil cooler.
The new 3.8-liter engine will be available for equipment manufacturers ahead of Tier 4 Final, taking effect in January 2015, for engines within the 75 hp-to-173 hp category.