In recent years there has been a successful application of engine downsizing in the passenger car market, using boosting technologies to achieve higher specific power and improve fuel economy. Downsizing has also been applied in heavy-duty diesel engines for the on-highway market to improve fuel economy, motivated in part by CO2 emission limits in place under Phase 1 greenhouse gas (GHG) legislation. In the non-road market, with Tier 4 emission standards already being met and no current plan for a GHG emission requirement, there has been less activity in engine downsizing and the drivers for this approach may be different from their on-highway counterparts. For instance, manufacturers may consider emission regulation break points as a motivation for engine displacement targets.Many non-road applications demand a relatively high low-end torque and support the use of higher displacement engines. For these applications it can be more challenging to apply downsizing strategies while meeting the operation requirements of the machine, such as load factor. However, if successful, downsizing in these applications and reducing the engine size can provide improvements in fuel economy, reduce purchase price and provide packaging and machine layout improvement opportunities.This work focuses on the application of downsizing in heavy-duty diesel engines applied to specific non-road applications where the opportunity exists to reduce the number of cylinders and thus the overall size of the engine. The main drivers here are packaging, production cost and fuel consumption. Various technologies, such as electrically assisted turbocharger, two-stage turbocharging, asymmetric twin scroll turbine and variable valve actuation, will be investigated to maintain performance requirements while reducing the number of cylinders.