Jaguar AJ6 engine
| Jaguar AJ6 | |
|---|---|
| Overview | |
| Manufacturer | Jaguar Cars |
| Production | 1984–1996 |
| Combustion chamber | |
| Configuration | DOHC I6 |
| Chronology | |
| Predecessor | Jaguar XK6 |
| Successor |
Jaguar AJ-V6 Jaguar AJ-V8 |
The AJ6 (Advanced Jaguar 6-cylinder), and the similar AJ16, was an inline-6 piston engine used by Jaguar in the 1980s and 1990s. It was designed to replace the much-loved Jaguar XK6 engine, and was introduced in 1984. The AJ6 was only the third engine ever designed by the company. The AJ16 was replaced in 1996 with the Jaguar developed Jaguar AJ-V8 engine.
Jaguar had considered cutting the V12 in half to build a V6, or possibly a V8, but chose instead to develop a new inline-6. The cylinders are inclined, as in a slant-6, by 22 degrees. It uses an aluminum block to reduce weight, and has an optional DOHC head for higher efficiency and power.
The original engines were the DOHC 3.6 and the SOHC 2.9. The DOHC 3.6 was revised and enlarged to 4.0 in 1990. It is still essentially an "AJ6", however. This was, as per usual, offered for the XJ-S before it was built into the XJ40 saloon.
The 3.6 was the first AJ6 engine, debuting in 1983 on the XJ-S. It had DOHC 4-valve heads with a 91 mm (3.6 in) bore and 92 mm (3.6 in) stroke. Power was 165 kW (224 PS; 221 hp) with 325 N·m (240 lb·ft) of torque. Power was reduced to 201 hp (150 kW) for versions having catalytic exhaust system. Early versions of the 3.6L AJ6 as used in the 1984 - 1987 XJ-S cars had a conventional distributor type of ignition system with electronics within the distributor body. This early AJ6 ignition system is nearly identical to the system used on the XK engine in the Series III XJ6 cars. The Lucas fuel injection system on the 3.6L AJ6 engines in these early XJ-S cars sensed engine load using a Manifold Absolute Pressure (MAP) sensor just like the V12 cars from the same era. Later 3.6L AJ6 engines as used in the 1986–1989 XJ40 cars had a crank-sensor type of ignition system with a bare distributor that only carried the spinning ignition rotor inside the distributor cap. The fuel-injection system used on the later 3.6L AJ6 engines used a hot-wire Mass Air Flow sensor to determine engine load.
Vehicles using the 3.6 were:
The 2.9 used a SOHC head from the Jaguar V12 engine, and was prone to failure. The block is the same as the 3.6, with the crankshaft and pistons lowering the stroke to 74.8 mm (2.9 in). Only the 1986–1989 Jaguar XJ6 used the 2.9. It was used for the entry-level XJ6 in Britain and Europe but rarely, if ever, seen in models exported to the US. The SOHC 2.9, which was generally considered somewhat underpowered for such a large car, was discontinued in 1990 (Actually 3.2 starts with a J-plate, so late 90 2.9 is possible) and replaced with a DOHC 3.2 (essentially identical to the DOHC 4.0).
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