The Toyota HD is a series of Diesel engines produced by Toyota.

1HD-T

The 1HD-T is a 12 valve 4164 cc straight-6 SOHC turbocharged direct injection diesel engine. Bore and stroke is 94x100 mm, with a compression ratio of 18.6:1. Output is 164 hp at 3,600 rpm with 361 Nm of torque at 1,400 rpm.

1HD-FT

The 1HD-FT is a 4164 cc straight-6 24 valve SOHC turbocharged direct injection diesel engine. Bore and stroke is 94x100 mm, with a compression ratio of 18.6:1. Known as the "multivalve" it has 4 valves per cylinder (2 inlet, 2 exhaust), central vertically mounted injector, and no glow plugs but rather an intake glow screen heater (like the later electronic 1HD-FTE below). The 4 valves per cylinder are actuated by the SOHC, by using bridges so each rocker actuates a pair of valves. Output is 168 hp ECE at 3,600 rpm with 380 Nm of torque ECE at 2,500 rpm. However, marinized version of 1HD (sold as Yamaha ME and Yanmar 6LP) have an output of 315 hp on Yanmar 6LP and 315 hp, 370 hp or 420 hp on Yamaha ME.

1HD-FTE

The 1HD-FTE is a 4164 cc straight-6 24 valve turbocharged diesel engine. Bore and stroke is 94x100 mm, with a compression ratio of 18.8:1. Output is 167 hp at 3,400 rpm with 380 Nm of torque at 1,400 rpm. The fuel system is direct injection, and adopts the electronic fuel injection (EFI) system. Redline of this engine is at 4200 rpm. The 4 valves per cylinder are actuated by the SOHC, by using bridges so each rocker actuates a pair of valves. The version with intercooler as fitted to HDJ100 station wagons has 202 hp at 3400 rpm with 430 Nm of torque at 1200-3200 rpm with a redline reaching 4200 rpm. A lower output 122 kW non-intercooled version powers HDJ78 Troop Carrier and HDJ79 Utility versions. Also some of the HDB50 and HDB51 Coasters are fitted with this 1HD-FTE engine.