Jaguar AJ-V8 Engine Specs

The Jaguar AJ-V8 is a naturally aspirated (and, in supercharged form, forced-induction) V8 petrol engine produced from 1996 to 2009, Jaguar's first V8 engine and a genuinely significant step in the brand's modern history, replacing the AJ6 inline-six across the XJ, XK, S-Type, and XF. Developed with considerable input from Jaguar's then-parent Ford, the AJ-V8 combined traditional Jaguar refinement with genuinely modern, competitive performance for the first time in the brand's post-1990s lineup.

Spanning displacements from 4.0 to 4.2 liters across its production run, the AJ-V8 produces between 290 and 420hp and 408-560Nm of torque depending on displacement and whether the engine is naturally aspirated or supercharged (as in the high-performance XKR), using a DOHC 32-valve head and a compression ratio of 10.75:1 in naturally aspirated form. The supercharged versions, in particular, gave Jaguar genuine competitiveness against contemporary German performance saloons and grand tourers, while the naturally aspirated versions offered smooth, refined power more in keeping with Jaguar's traditional character.

As a used-car proposition, AJ-V8-powered Jaguars require awareness of a few well-documented issues specific to this generation. Timing chain tensioners, particularly on pre-2003 examples, are a known weak point; tensioner failure can allow the chain to jump timing, causing serious engine damage, and this is one of the most important things a prospective buyer should have checked, ideally with documentation that any updated tensioner parts have been fitted. The Nikasil cylinder bore coating used on some early engines was found to be incompatible with high-sulphur fuel in certain markets, leading to bore wear; while later production addressed this, it's worth confirming which coating type a specific engine uses if buying an early example. Supercharged versions place additional demand on the cooling and lubrication systems and should have a clearly documented maintenance history. General age-related wear - vacuum hoses, electrical connectors, and suspension components common to Jaguars of this era - should also be part of any thorough pre-purchase inspection.