Cummins announced that its QSB4.5 engine will meet Tier 4-Final emissions standards with top-rated power increased to 173 horsepower and a higher peak torque of 520 lb.-ft. The 4-cylinder, 4.5-liter engine has a Cummins VGT variable-geometry turbocharger that enables the higher ratings to reach performance levels previously associated with a larger 6-cylinder engine, Cummins says.
For the QSB4.5 lower ratings down to 121 horsepower, the VGT technology improves transient response on a fuel-efficient basis. For equipment operation, this means a stronger, faster response to increasing load demands compared to Tier 4-Interim.
The Tier 4-F QSB4.5 engine platform retains the same cooled Exhaust Gas Recirculation (EGR) system proven with Cummins’ Tier 4-I engine, including the Cummins Compact Catalyst (CCC) aftertreatment with the addition of selective catalytic reduction (SCR) in the exhaust stream. The combined CCC-SCR aftertreatment is designed and manufactured by Cummins Emission Solutions.
The patented VGT is a smaller version of the one used on Cummins 6-cylinder engines. The VGT features a one-piece sliding-nozzle to precisely adjust the airflow delivered to the engine..
To remove particulate matter (PM) from the exhaust, the CCC aftertreatment takes up a smaller space claim than a diesel particulate filter (DPF), Cummins says.
The very low nitrogen oxide (NOx) emissions levels required for Tier 4-F are achieved by incorporating SCR aftertreatment in the exhaust stream, configured for compact 4-cylinder applications. The SCR uses a catalyst specified to deliver a robust solution, able to operate more efficiently at lower temperatures and features advanced sensors to provide full closed-loop control. Diesel exhaust fluid (DEF) dosing levels are minimized due to an enhanced mixing technique.
The QSB4.5, together with the recently announced QSF3.8 and QSF2.8, extend Cummins 4-cylinder engine range to a broadest ever 49- to-173 horsepower capability for Tier 4-F emissions standards.