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Cummins 4-Cylinder QSB3.3 and QSB4.5 to meet Tier 4 Interim Emissions with integrated Air-Intake-to-Exhaust System


Compact Power Capability Extends From 75 to 160 hp (56 to 119 kW)

COLUMBUS, Ind. – Cummins Inc. (NYSE: CMI) announced today that the 4-cylinder QSB3.3 and QSB4.5 engines will meet EU Stage IIIB and U.S. EPA Tier 4 Interim off-highway emissions in 2012 across a broad 75- to 160-hp (56 to 119 kW) power range.

The next-generation 4-cylinder QSB engines retain the same 3.3- and 4.5-liter proven platforms and will be supplied as a fully integrated air-intake-to-exhaust system. Very low emissions are achieved by using cooled Exhaust Gas Recirculation (EGR) for NOx control and exhaust aftertreatment for removing particulate matter.

Both the cooled-EGR system and the particulate aftertreatment unit have been specifically developed for the 4-cylinder platforms as a more compact and simplified version of the Tier 4 Interim technology previously announced for the 6-cylinder QSB6.7 engine. The High Pressure Common Rail (HPCR) fuel system employed on the Tier 3 QSB3.3 and QSB4.5 is already capable for Tier 4 Interim and will require no major change. An upgraded turbocharger with electronic control will be utilized to manage EGR flow across the entire engine rpm range.

QSB3.3 ratings extend from 75 to 110 hp (56 to 82 kW) for Tier 4 Interim, retaining the best-in-class power output for an engine of this size. The QSB4.5 occupies the 110- to 160-hp (82 to 119 kW) power band and will offer the same or improved torque delivery as the Tier 3 engine. Cleaner and more efficient combustion improves fuel efficiency by up to 5 percent compared to Tier 3, depending on rating and installation optimization.

“By utilizing the right technology for our 4-cylinder engines with an integrated air-intake-to-exhaust system, we are able to achieve very low emissions with improved fuel efficiency. The QSB3.3 and QSB4.5 at Tier 4 Interim will look very familiar to current customers of the Tier 3 engines, who can expect the same outstanding levels of reliability and durability they are widely recognized for,” said Hugh Foden, Executive Director, Cummins Off-Highway Business.

“Our 4-cylinder development program for Tier 4 Interim was driven by the need to avoid the complexity of increasing displacement or overloading the engines with complications such as dual turbochargers. We have instead focused on minimizing the installation impact for our OEM customers with space-saving solutions such as the Cummins Direct Flow™ air filtration system, and we’ve scaled down the EGR and aftertreatment technology appropriately for these compact engines,” added Foden.

Integrated Air-Intake-To-Exhaust Aftertreatment

The particulate aftertreatment unit designed by Cummins for the Tier 4 Interim QSB3.3 and QSB4.5 removes over 90 percent of particulate matter. The unit replaces the muffler in the exhaust stream and offers equivalent noise reduction. While meeting the toughest vibration and shock loading requirements, the particulate aftertreatment unit is configured to be as space-efficient as possible, with both horizontal and vertical installation options available.

The Cummins Direct Flow air filtration system provides a 35 percent smaller installation profile than radial air filters, yet retains the same filtration efficiency. This is accomplished by creating a direct-flow path through the filter media, which is packaged in a rectangular configuration rather than a conventional cylindrical shape.

Cummins expertise in air filtration is also employed to prevent crankcase blowby gas escaping from the engine with a high-efficiency crankcase filter. The filter also eliminates oil mist and tiny oil droplets to maintain clean engine operating conditions.

The 4-cylinder QSB3.3 and QSB4.5 now join the 6-cylinder QSB6.7 to complete the QSB lineup ready for Stage IIIB and Tier 4 Interim. With the engine family extending from 75 to 300 hp (56 to 224 kW), this will offer equipment manufacturers the benefit of engine commonality across a very wide range of compact, mid-size and larger equipment.


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