The WHSC test is a steady-state engine dynamometer schedule defined by the global technical regulation (GTR) No. 4  developed by the UN ECE GRPE group . The GTR is covering a world-wide harmonized heavy-duty certification (WHDC) procedure for engine exhaust emissions. Two test cycles, a hot start steady state test cycle (WHSC) and a transient test cycle (WHTC) with both cold and hot start requirements, have been created covering typical driving conditions in the EU, USA, Japan and Australia.
The WHSC is a ramped steady-state test cycle, with a sequence of steady-state engine test modes with defined speed and torque criteria at each mode and defined ramps between these modes. The parameters of the WHSC are listed in Table 1.
|† Including 20 s ramp|
The WHSC is run from a hot start, following engine preconditioning at mode 9. The idle mode is separated in two modes, mode 1 at the beginning and mode 13 at the end of the test cycle. Mode 0 is not run, but is only accounted for mathematically by a weighting factor of 0.24 and zero emissions and power.
For calculation of the brake specific emissions, the actual cycle work is calculated by integrating actual engine power over the cycle. The weighting factors (WF) are given for reference only.