Toyota HZ engine

The Toyota 1HZ is a straight-six diesel engine developed and produced by Toyota Motor Corporation beginning in 1990. It continues to be offered in vehicles sold in countries with lax emissions regulations, and those sold by Toyota Gibraltar Stockholdings for organisations such as the United Nations.

Toyota HZ engine
A Toyota 1HZ engine installed in the Land Cruiser.
Overview
ManufacturerToyota Motor Company
Production1990–present
Layout
ConfigurationStraight-6
Displacement4.2 L (4,164 cc)
Cylinder bore94 mm (3.70 in)
Piston stroke100 mm (3.94 in)
Cylinder block materialCast iron
Cylinder head materialCast iron
ValvetrainSOHC with 2 valves per cylinder
Valvetrain drive systemTiming belt
Compression ratio22.4:1
RPM range
Max. engine speed4000
Combustion
Fuel systemMechanical fuel injection
Fuel typeDiesel
Oil systemWet sump
Cooling systemWater-cooled
Output
Power output131 PS (129 hp; 96 kW)
Torque output285 N⋅m (29 kg⋅m; 210 lb⋅ft)
Chronology
PredecessorToyota H engine
Bottom view of the 1HZ head
Bottom view of 1HZ/1HDT connecting rods and crank
Front view of 1HZ/1HDT timing gears (1HZ uses a timing belt to drive the camshaft).

The 1HZ generates more power and torque than the previous 2H diesel engine. Despite being 30 years old, the 1HZ still sees use in Land Cruiser J70 production worldwide with the exception of petrol-only markets, Euro 4, and Australian markets, where the 1GR-FE and 1VD-FTV Turbo-Diesel is supplied respectively. A popular engine in the 80 series Land Cruiser, it replaced the 2H engine in the 80/85 series by 1990.

The 1HZ Toyota Landcruiser 4.2 litre (4164 cc) diesel inline 6-cylinder 12-valve SOHC (single overhead camshaft) is an indirect injection design, and delivers maximum power of 96 kW (129 hp) at 3800 rpm and maximum torque of 285 N⋅m (210 lbf⋅ft) at 2200 rpm.

The 5-cylinder variant of this engine is known as 1PZ.