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  • August 2013 Torque - The New Cummins QSM12

August 2013 Torque - The New Cummins QSM12

Meeting Tier 4 Emissions Without EGR

Jul 16, 2013
We are all affected in one way or another by the current stringent emissions regulations in the U.S. Diesel engines have been burdened with Band-Aid devices such as exhaust gas recirculation, particulate filters, oxidation catalysts, and urea-injection aftertreatments in an attempt to meet these tight standards. So when a company as well regarded as Cummins announces it has been able to produce a new engine that meets EPA Tier 4 Final emissions requirements—without the use of EGR—we had to take a closer look.
Photo 2/4   |   August 2013 Torque The New Cummins Qsm12 Front Three Quarter
The Cummins QSM12 is an all-new engine, built from the ground up with the intention of having a higher power-to-weight ratio than other engines in its class, while meeting the near-zero emissions regulations of EPA Tier 4 Final. A sculpted block retains high rigidity, while removing unnecessary weight. Composite materials make up the oil pan and valve cover, contributing to the weight savings. The six-cylinder, 12.0L engine is capable of producing up to 512 hp and 1,700 lb-ft of torque, and with an engine weight of only 1,900 pounds, it delivers a top-rated power-to-weight ratio of 0.27 hp per pound.
An ultra-high-pressure fuel injection system, Cummins Xtra-High Pressure Injection (XPI), derived from the company’s larger and more powerful QSX15 engine, was scaled down and implemented on the new QSM12. The Cummins XPI injection pump is capable of delivering up to 35,000 psi of injection pressure and delivers multiple injection events per engine cycle, creating less noise and vibration, and smoother power delivery. Higher-efficiency air handling and advanced combustion using the XPI system allow the QSM12 to return to the simplicity of a single, wastegated turbocharger.
Photo 3/4   |   August 2013 Torque The New Cummins Qsm12 Front Shot
Thanks to the high-efficiency turbocharging and XPI injection system, the QSM12 achieves near-zero emissions without the need for a cooled exhaust gas recirculation (EGR) system. As a result, internal loads are reduced on the engine, allowing it to free up extra power potential. Cummins Emission Solutions (CES) has designed a fully integrated air intake to exhaust aftertreatment package that includes a diesel particulate filter (DPF) and selective catalytic reduction (SCR). DPF regeneration occurs less than 1 percent of engine running time. The SCR system developed by Cummins for Tier 4 Final emissions requirements is a next-generation design with a copper zeolite-based catalyst capable of converting more than 95 percent of nitrogen oxide emissions.
Photo 4/4   |   August 2013 Torque The New Cummins Qsm12 Turbo Side
While this emissions technology is still new in the off-highway engine segment, we hope it won’t be long before it trickles down to over-the-road engines, and eventually to the light-duty truck market. We are excited by the proposition of once again meeting emissions without the use of Band-Aids such as EGR, DPF, and SCR.
“For Tier 4 Final, the QSM12 sets a new benchmark for heavy-duty engines with its ability to outperform any comparable engine, yet provide a smaller, lighter, and simpler engine package to install.”
— Hugh Foden, Executive Director – Cummins Off-Highway
Fast Specs
Engine: Cummins QSM12
Displacement: 12.0L
Cylinders: Inline-six
Horsepower: Models from 335 hp to 512 hp
Torque: 1,700 lb-ft
Weight: 1,900 pounds
Induction: Single wastegated, fixed-geometry turbocharger
Fueling: Cummins Xtra-High Pressure (XPI) common-rail injection
Emissions: EPA Tire 4 Final / European Union Stage IV
Emissions Equipment: DPF / SCR



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