Cummins 4-Cylinder QSB3.3 and QSB4.5 to Meet Stage IIIB / Tier 4 Interim Emissions

The Cummins 4-Cylinder QSB3.3 and QSB4.5 include integrated air-intake to the exhaust system.

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

The next generation 4-cylinder QSB engines retain the same 3.3-litre and 4.5-litre 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.

Tier-4 Interim Emissions 

The High-Pressure Common-Rail fuel system employed on the Tier 3 QSB3.3 and QSB4.5 is already capable of meeting Tier 4 Interim and will require no major change. An upgraded turbocharger with electronic control will be utilised to manage EGR flow across the entire engine rpm speed range. 

QSB4.5 and QSB3.3 Engines

QSB3.3 ratings extend from 56 to 82 kW (75 to 110 hp) for Tier 4 Interim, retaining the best in class power output for an engine of this size. The QSB4.5 occupies the 82 to 119 kW (110 to 160 hp) 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, dependent on rating and installation optimization.

“By utilising 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,” said Hugh Foden, Executive Director, Cummins Off-Highway Business. 

The QSB3.3 and QSB4.5 at Tier 4 Interim will look very familiar to current customers of the Tier 3 engines - and can expect the same outstanding levels of reliability and durability they are widely recognized for.” 

“Our 4-cylinder development program for Tier 4 Interim was driven by the need to avoid the complexity of increasing displacement or over-loading the engines with complications such 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-filter and 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 attenuation. 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 filter provides a 35 percent smaller installation profile than radial air filters, yet retaining 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 line-up ready for Stage IIIA and Tier 4 Interim. With the engine family extending from 56 to 224 kW (75 to 300 hp) this will offer equipment manufacturers the benefit of engine commonality across a very wide range of compact, mid-size and larger equipment.