Toyota AZ engine

Toyota AZ engine
Overview
Manufacturer Toyota Motor Corporation
Production 2000–2012
Chronology
Predecessor Toyota S engine
Successor Toyota AR engine

The Toyota AZ engine family is a straight-4 piston engine series. The AZ series uses an aluminium engine block with cast iron cylinder liners and aluminium DOHC cylinder heads. The engine series features many advanced technologies including slant-squish combustion chambers, offset cylinder and crank centers, and the VVT-i continuously variable intake valve timing system. The aluminium engine measures 626 mm (25-in) long, 608 mm (24-in) wide, and 681 mm (27-in) tall.

The cylinder block is an open-deck, midi-skirt die-cast aluminium type with cast-in iron liners and a die-cast aluminium lower crankcase and a stamped oil pan. The forged steel crankshaft is fully balanced with eight counterweights and supported by five main bearings. A helical gear pressed in No. 3 counterweight drives twin contra-rotating balance shafts in the shaft housing within the lower crankcase.

The dual overhead camshafts are driven by a single-stage roller chain of 8.0 mm (0.3-in) pitch, enabling a narrow included valve angle of 27.5°. The camshafts act on four valves per cylinder via bucket tappets. As in the recent Toyota engine practice, no clearance adjusting shim is employed. Valve diameters are 34.0 mm (1.3 in) for intake and 29.5 mm (1.2 in) for exhaust, with 8.0 mm (0.3-in) lift for both intake and exhaust. The four-vane VVT-i device is fitted on the intake camshaft, altering timing by 50°. The valve cover is made of magnesium to save weight.

Fuel is injected sequentially via an ultra-fine-atomization injector with twelve small injection holes, each 0.18 mm (0.01 in) in diameter. As in the smaller NZ engine, the new AZ adopts a plastic, built-up, and vibration-welded intake manifold integrating a large volume plenum chamber (3.5 L (214 in3) volume including a 1.3 L (79 in3) resonator). Exhaust manifolds are of tubular construction with integrated catalytic converters.

The AZ is the replacement for the S engine. It will eventually be replaced by the AR engine.

1AZ-FE

The 1AZ-FE is a 2.0 L (1998 cc) version. Output is 108 kW (145 hp) at 6000 rpm with 190 N·m (140 lb·ft) of torque at 4000 rpm for the Camry Aurion version. Rav4 and Ipsum engines were rated at 148–150 hp (110–112 kW) at 6000 rpm and 142 lb·ft (193 N·m) of torque at 4000 rpm.

The 1AZ has a total displacement of 1998 cc with 86.0 mm (3.39 in) bore and 86.0 mm (3.39 in) stroke, and a compression ratio of 9.6:1.

Applications:

1AZ-FSE

The 1AZ-FSE is a 2.0 L (1998 cc) version. Bore is 86.0 mm and stroke is 86.0 mm, and a compression ratio of 10.5:1. Output is 150 PS (110 kW; 148 hp) at 5700 rpm with 200 N·m (148 lb·ft) of torque at 4000 rpm. The 1AZ-FSE features Toyota's D-4 direct injection system.

Applications:

2AZ-FE

The 2AZ-FE is a 2.4 L (2362 cc) version built in Japan (Kamigo Plant and by Toyota Industries Corporation) and at TMMK in the USA, obtains a total displacement of 2362 cc with 88.5 mm (3.5 in) bore and 96.0 mm (3.8 in) stroke, with a compression ratio of 9.6:1. Output is 160 hp (120 kW) at 5600 rpm;162 lb·ft (220 N·m) of torque at 4000 rpm.

Later versions of the 2AZ-FE engine were upgraded with 9.8:1 compression ratio, a slightly more aggressive intake cam profile, 6500 rpm red line, and piston oil squirters. These later versions are rated at 161 hp (120 kW) in the Scion tC, 168 hp (125 kW) in the Rav4, and 158 hp (118 kW) in the Camry, Corolla XRS, and Scion xB. However, these latter 2AZ-FE models were the first to be rated under the new SAE J1349 standard. The new standard usually produces more conservative numbers, though no definitive comparison is available since the two versions were never tested by the same standard.The Rav 4 uses a different timing chain cover than the Camry, they can however be interchanged.

A TRD supercharger was available for the Scion tC until Spring 2009.

This engine is prone to "burning oil" issue starting after 45k miles, though mostly after 60k-75k miles. Toyota has even issued a TSB (Technical service bulletin) TSB #0094-11 in August 2011 but have refused to issue general recall. There are several class-action lawsuits underway regarding this widespread issue. In January 2015, Toyota caved in and issued extended warranty notification (ZE7) for this issue. However, Toyota still insists that burning 1 quart of oil every 1200 miles is "normal".

Applications:

2AZ-FSE

The 2AZ-FSE is a 2.4 L (2362 cc) version. Bore is 88.5 mm and stroke is 96.0 mm, and a compression ratio of 11.0:1. Output is 163 PS (120 kW; 161 hp) at 5800 rpm with 231 N·m (170 lb·ft) of torque at 3800 rpm. The 2AZ-FSE features Toyota's D-4 direct injection system.

Applications:

2AZ-FXE

The 2AZ-FXE is an Atkinson cycle variant of the 2AZ-FE. It has the same bore and stroke, but the cams and pistons are unique. It has a physical compression ratio of 12.5:1.

The large valve overlap leads to a reduction in cylinder charge and reduced torque and power output, but efficiency is increased. This combination makes the 2AZ-FXE suitable for use only in hybrid vehicles, where peak torque and power demands can be met by the electric motor and battery.

Maximum output when used in the Camry hybrid is 147 hp (108 kW) at 6000 rpm with 138 lb·ft (187 N·m) of torque at 4400 rpm.

Applications:

See also

Wikimedia Commons has media related to Toyota AZ engines.

References

  1. ↑ Scion xB specification page