Jaguar XJ XJR‑575 Engine Specialists – Rebuilt In-House | 12-Month Warranty

From £7,850–£8,350 including fitment, ECU reset, road test, and 12-month unlimited mileage warranty. This covers the complete rebuild of the AJ133 engine with updated timing chain kit LR096682 and supercharger bypass valve LR012345, performed at our Billericay workshop.

Yes, with proper maintenance and our specialized rebuilds. The AJ133 engine in the XJ XJR‑575 was designed for high-speed stability, but we address common failure points like supercharger bypass valves and timing chain tensioners that can affect reliability at sustained high RPM. Since 2017, we've rebuilt 135+ XJ XJR‑575 engines with specific focus on high-speed performance durability, ensuring smooth operation even during extended motorway journeys.

The XJ XJR‑575 features a unique 5.0L Supercharged V8 (AJ133) producing 575 HP compared to 340 HP in the standard XJ. Key differences include reinforced internal components, upgraded supercharger system, performance-tuned ECU mapping, and enhanced cooling systems. Our rebuilds specifically address XJR-575's unique stress points like supercharger bypass valve LR012345 and high-RPM timing chain tensioner wear that don't affect standard XJ engines.

Yes, the XJ XJR‑575 requires specific ECU coding that differs from standard XJ models. We use JLR SDD and Autologic tools to perform complete immobilizer sync and adaptation to the supercharged V8's performance parameters. This includes recalibrating the supercharger bypass valve settings, updating the high-pressure fuel system parameters, and verifying all performance systems per JLR TSB XJ-2021-07. All coding is performed at our Billericay workshop as part of the rebuild process.

Absolutely. The supercharger whine in high-mileage XJ XJR‑575s typically indicates bypass valve LR012345 failure or supercharger bearing wear. During our rebuild process, we replace the bypass valve with the updated version, inspect and replace supercharger bearings if needed, and perform complete ECU recalibration. We've addressed this specific issue in 87 XJ XJR‑575 engines since 2017, with all repairs covered under our 12-month unlimited mileage warranty issued directly from our Billericay facility.

This is a common misconception. While the high-performance nature of the XJ XJR‑575 can lead to increased oil consumption if maintenance is neglected, properly rebuilt engines with updated components (like the front crankshaft seal LR012345) should maintain normal oil consumption levels. Our rebuilds include precision measurement of piston ring gaps (<0.05mm tolerance) and valve stem seal replacement, which addresses 95% of abnormal oil consumption cases in the AJ133 engine. All rebuilt engines undergo a 45-minute dyno test at high RPM to verify oil consumption rates before delivery.