The Jaguar AJ-V6 engine is a piston engine based on the Ford Duratec V6 engine.^[2] The Duratec V6 was originally a Porsche design, purchased by the Ford Motor Company with Cosworth finishing the engineering to suit Ford's needs. One notable addition is the use of variable valve timing, a feature also shared with Mazda's version of the engine. It is available in 2.1 L (2,099 cc), 2.5 L (2,495 cc) and 3.0 L (2,967 cc) displacements.

The AJ-V6 engine has an aluminium engine block and Jaguar Cars designed aluminium DOHC cylinder heads. It uses sequential fuel injection, has 4 valves per cylinder with VVT, features fracture-split forged powder metal connecting rods and a one-piece cast camshaft and has direct-acting mechanical bucket (DAMB) tappets, these design aspects differentiating the AJ-V6 from the Ford and Mazda versions.

AJ20

The AJ20 2.1 L (2,099 cc) version has an 81.6 mm × 66.8 mm (3.21 in × 2.63 in) bore and stroke. Although it displaces nearly 2.1 litres (2,099 cc), it is marketed as a "2.0". It produces 157 hp (117 kW; 159 PS) and 148 lb⋅ft (201 N⋅m). The compression ratio is 10.75:1.

This engine is used in the following vehicles:

• Jaguar X-Type 2.0 (UK)

AJ25

The AJ25 is a 2.5 L; 152.3 cu in (2,495 cc) version built. It shares the 2.1's 81.6 mm (3.21 in) bore and is stroked to 79.5 mm (3.13 in), the same as the 3.0 L (2,967 cc). It delivers 193 hp (144 kW; 196 PS) at 6800 rpm with 178 lb⋅ft (241 N⋅m) of torque at 3000 rpm from 10.3:1 compression.

This engine is used in the following vehicles:

• 2001-2009 Jaguar X-Type 2.5, 193 hp (144 kW; 196 PS) and 180 lb⋅ft (244 N⋅m)
• 2002-2006 Jaguar S-Type 2.5 (UK), 201 hp (150 kW; 204 PS) and 185 lb⋅ft (251 N⋅m)

AJ30

The AJ30 is a 3.0 L (2,967 cc) version and is the most common, especially considering the Duratec 30. It has an 89 mm (3.5 in) bore and shares the 2.5's 79.5 mm (3.13 in) stroke. In the X-Type, it produces 228 hp (170 kW; 231 PS) and 209 lb⋅ft (283 N⋅m). The Jaguar XF debuted a refined version of the AJ30 with continuously variable cam-phasing and variable geometry air intakes to increase power and broaden the powerband up to its 6800 rpm redline.

This engine is used in the following vehicles:

• 2000-2008 Jaguar S-Type, 240 hp (179 kW; 243 PS) and 221 lb⋅ft (300 N⋅m)
• 2002-2009 Jaguar X-Type, 228 hp (170 kW; 231 PS) and 209 lb⋅ft (283 N⋅m)
• 2003-2010 Jaguar XJ, 237 hp (177 kW; 240 PS) and 216 lb⋅ft (293 N⋅m)
• 2008-2011 Jaguar XF 240 hp (179 kW; 243 PS) and 221 lb⋅ft (300 N⋅m)
• 2000-2006 Lincoln LS