The AJ6 (and 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 AJ6 was replaced in 1996 with the Ford Duratec-derived Jaguar AJ-V6 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 is uses an aluminium block to reduce weight, and has an optional DOHC head for higher efficiency and power.
3.6
The 3.6 was the first AJ6 engine. It had DOHC 4-valve heads with a 91 mm bore and 92 mm stroke. Power was 165 kW with 325 Nm of torque.
Vehicles using the 3.6 were:
1984-1989 Jaguar XJS
1984-1989 Jaguar XJ6
1984-1989 Jaguar XJ6 Sovereign
1984-1989 Daimler
2.9
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. Only the 1984-1989 Jaguar XJ6 used the 2.9.
AJ16
The 4.0 L (3980 cc) version, called AJ16, replaced the AJ6 in 1989. It featured a longer 102 mm stroke, and generated 183 kW and 392 Nm.
Cars using the 4.0 included:
Jaguar XJS
Jaguar XJ6
Jaguar XJ6 Sovereign
Jaguar XJ6 Sport
Daimler
AJ16S
A supercharged version of the 4.0 L AJ16 was released in 1990 in the Jaguar XJR. It used an Eaton blower to boost output to 240 kW and 512 Nm.
3.2
The final version of the AJ6 was the 3.2 litre. It was a de-stroked (to 83 mm) 4.0 and produced 149 kW and 298 Nm.
The 3.2 was used in the following cars:
Jaguar XJ6
Jaguar XJ6 Sovereign
Jaguar XJ6 Sport