Achieving near-zero emissions levels in an engine delivering 74 hp to 130 hp (55-98 kW) without compromising power, performance or fuel economy is a big challenge. Yet that’s exactly what Cummins engineers have achieved in the QSF3.8 – without the need to add a DPF to the aftertreatment system. At 74hp, the QSF3.8 uses a simple “fit and forget” Diesel Oxidation Catalyst (DOC).  Cummins DOC, a flow-through device requiring no ash-cleaning service, no sensors and no operational lamps in the equipment cab, enables a smaller, easier and more flexible equipment installation than Diesel Particulate Filters (DPF) typically used by many other engines below 75 hp looking to meet the requirement for near-zero emissions.

From 100-130 hp, the QSF3.8 is paired with a Diesel Oxidation Catalyst and Selective Catalytic Reduction (DOC-SCR) system designed by Cummins Emission Solutions (CES). Cummins SCR enables oxides of nitrogen (NOx) conversion to take place at lower exhaust temperatures. CES has manufactured over 1 million SCR systems – and has more experience with this technology than any other company. The Cummins SCR system features a decomposition tube designed to enable more effective mixing of the Diesel Exhaust Fluid (DEF) ahead of the catalyst. Additionally, for certain applications, the QSF3.8 can be paired with an SCR-only aftertreatment system.

This technology path also allows the QSF3.8 to reduce the amount of cooled exhaust gas being recirculated through the combustion chamber, increasing the power output to the highest level of any engine in the sub-4-liter engine class while simultaneously keeping fuel efficiency comparable to that of our Tier 4 Interim 3.3-liter engine.

Full-authority electronic controls and industry-standard data links make it easier to electronically integrate the QSF3.8 with equipment, as well as track engine performance data and perform routine servicing on this engine. A wastegated turbocharger from Cummins Turbo Technologies is simple and robust in design. The QSF3.8 engine’s small size and multiple aftertreatment options make installation easier for design engineers.

Maintenance is kept at an absolute minimum with a crankcase ventilation breather that requires no filter element, and a Cummins Filtration Direct Flow air cleaner that has a higher dust capacity, for extended filter change intervals – up to twice those of conventional air cleaners. The QSF3.8 delivers an unprecedented combination of high-performance, reliable emissions technology, low-cost installation and reduced operational costs, making it ideal for rental applications – all in an engine with the ease of use and robust performance that is critical for rental equipment, redefining the meaning of compact power for an entire industry.

Cummins QSF3.8 Engine Ratings