Isuzu CNG engines

The Isuzu CNG engines are two compressed natural gas engines described in the CNG section of the Wikipedia list of Isuzu engines, which says that Isuzu developed its first CNG engine series as a low-emissions truck engine with zero black smoke. The 4HF1-CNG has a capacity of 4.334 L with non-contact ignition, a bore of 115 mm and a stroke of 108 mm, and produces 120 PS at 1,500 rpm and a peak torque of 323 Nm. The 4HV1 has a capacity of 4.570 L, a bore of 115 mm and a stroke of 110 mm, and produces 170 PS at 3,200 rpm and 353 Nm. The list says the 4HV1 was used for the NPR300 CNG series.