Nonroad Transient Cycle (NRTC)

Time-speed-torque data points

The NRTC test is a transient driving cycle for mobile nonroad diesel engines developed by the US EPA in cooperation with the authorities in the European Union (EU). The test is used internationally for emission certification/type approval of nonroad engines. NRTC testing is required by a number of emission standards for nonroad engines, including the EU Stage III/IV regulation, the US EPA Tier 4 rule and Japanese 2011/13 regulations.

The cycle is an engine dynamometer transient driving schedule of total duration of 1238 seconds. The normalized engine speed and torque during the NRTC test are shown in the following chart.

Figure 1. Normalized speed and torque over NRTC cycle

The NRTC is run twice, with a cold and a hot start, with a 20-minute soak period between the tests. The cold start weighting factors are 10% in the EU and 5% in the United States.

The average power is about 37% of the maximum engine power. The NRTC has higher speeds and loads than the WHTC test used for highway engines, resulting in faster achievement of operating temperatures for exhaust aftertreatment.