Toyota NZ engine

The Toyota NZ engine family is a straight-4 piston engine series. The 1NZ series uses aluminum engine blocks and DOHC cylinder heads. It also uses sequential fuel injection, and has 4 valves per cylinder with VVT-i.

The 1NZ-FXE is the earliest 1.5 L (1497 cc) version built in Japan. Bore is 75 mm (2.95 in) and stroke is 84.7 mm (3.33 in). It features forged steel connecting rods and an aluminum intake manifold. The engine has a high physical compression ratio of 13.0:1, but the closing of the inlet valve is delayed. The net result is that the engine has a greater effective expansion than compression—making it a simulated Atkinson cycle, rather than a conventional Otto cycle.

The reduction in cylinder charge means reduced torque and power output, but efficiency is increased. This combination makes the 1NZ-FXE suitable for use with the Hybrid Synergy Drive, where peak torque and power are of less importance. Output is 57 kW (76 hp) at 5000 rpm with 115 Nm (85 lb·ft) of torque at 4000 rpm. Thermal efficiency is about 37%. Production was discontinued in 2009, with the arrival of the Prius Gen 3, which replaced the 1NZ-FXE with the 2ZR-FXE.

In 2012, upon the arrival of the Prius c (North America), the Prius Aqua (Japan), and the Yaris Hybrid (Europe), an improved version was introduced. Without any belt-driven accessories, and a physical compression ratio of 13.4:1, the new version delivers an output of 54 kW (74 hp) at 4800 rpm with 111 Nm (82 lb·ft) of torque at 3600–4400 rpm.

The 1NZ-FXE Hybrid Synergy Drive in the Toyota Prius has won several International Engine of the Year awards:

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