Four generations of Jaguar V8, from the early 4.0‑litre Nikasil‑susceptible AJ26 to the ultimate 5.0‑litre supercharged AJ133. Exactly which models got which engine, how to tell them apart, and why the distinction matters when buying a replacement.
Jaguar's AJ‑V8 family spans four distinct engine codes – AJ26, AJ27, AJ34 and AJ133 – each with different displacements, revisions, and known issues.
Full model‑by‑model fitment table below, plus how to confirm which engine your Jaguar actually has.
Every Jaguar model that used any of the four AJ‑V8 variants, with engine code, displacement, years, and badges.
| Model | Engine Code | Displacement | Badge(s) | Years | Notes |
|---|---|---|---|---|---|
| XK8 / XKR (X100) | AJ26 (early) / AJ27 (late) | 4.0 L | 4.0, 4.0 SC | 1996–2002 (AJ26), 1999–2003 (AJ27) | AJ26 Nikasil risk; AJ27 improved |
| XJ8 / XJR (X308) | AJ26 (early) / AJ27 (late) | 4.0 L | 4.0, 4.0 SC | 1997–2002 (AJ26), 1999–2003 (AJ27) | Same Nikasil/improvement timeline |
| S‑Type (X200) | AJ26 (early V8) / AJ27 | 4.0 L | 4.0 V8 | 1999–2002 | Early S‑Type used AJ26, later AJ27 |
| XK (X150) 4.2 | AJ34 | 4.2 L | 4.2, 4.2 SC | 2006–2010 | NA and supercharged (XKR) |
| XJ (X350) 4.2 | AJ34 | 4.2 L | 4.2, 4.2 SC | 2003–2010 | Used in XJ8, XJR |
| S‑Type R (X200) | AJ34 (supercharged) | 4.2 L | 4.2 SC | 2002–2008 | Supercharged 4.2 in S‑Type R |
| XF X250 4.2 | AJ34 | 4.2 L | 4.2 V8, 4.2 SC | 2008–2009 | Early XF used 4.2 before moving to 5.0 |
| XK (X150) 5.0 | AJ133 | 5.0 L | 5.0, 5.0 SC | 2010–2015 | NA and supercharged (XKR, XKR‑S) |
| XF X250 5.0 | AJ133 | 5.0 L | 5.0 V8, 5.0 SC | 2010–2015 | XF‑R used supercharged 5.0 |
| XF X260 5.0 | AJ133 | 5.0 L | 5.0 SC | 2016–2024 | XF‑R and SVR variants |
| XJ X351 5.0 | AJ133 | 5.0 L | 5.0, 5.0 SC | 2010–2019 | XJ, XJ‑R, XJ Supersport |
| F‑Type (X152) | AJ133 | 5.0 L | 5.0 SC, SVR | 2013–2024 | Supercharged 5.0 in V8 variants |
| F‑Pace SVR (X761) | AJ133 | 5.0 L | 5.0 SC | 2017–2024 | Supercharged 5.0 in F‑Pace SVR |
Model years are approximate; changeovers between AJ26 and AJ27 occurred mid‑production. Always confirm by engine number, not by model year alone.
From the early 4.0‑litre to the ultimate 5.0‑litre supercharged, each generation addressed the weaknesses of its predecessor.
The AJ133 is not just a bigger AJ34 – it is a different engine design, sharing only the family name. Parts compatibility between generations is minimal [EM-INTERVIEW].
Located on the block, typically on the left‑hand side near the starter motor. The prefix (AJ26, AJ27, AJ34, AJ133) is the definitive identifier. Full location diagram on our Engine Number Location guide.
The fastest method. Our Registration Lookup tool cross‑references your plate against build data instantly.
AJ133 has a distinctive plastic intake manifold and different cam covers compared to the earlier engines. Supercharger placement also differs – AJ133 supercharger is side‑mounted, while AJ34 is top‑mounted.
The four AJ‑V8 generations are not interchangeable. Engine mounts, ECU pin‑outs, cooling system routing, gearbox bellhousing patterns, and even physical length differ. A supplier quoting for "a Jaguar V8" without confirming the exact code is quoting blind.
Costs vary significantly: a reconditioned AJ133 supply‑only runs £5,500–£9,000 [EM-QUOTE], while an AJ34 is typically £3,500–£6,000 [ESTIMATED]. Fitting labour is also model‑dependent – an F‑Type engine swap is more involved than an XJ. Always confirm the code before agreeing to a quote.
The specific wrong answers people arrive at, and why.
Both are 4.0‑litre, but AJ27 has steel cylinder liners (AJ26 has Nikasil). The engine number prefix is the only definitive way – it will start with AJ26‑ or AJ27‑. Visually, they are nearly identical. If your car is pre‑1999, it's almost certainly AJ26; post‑1999, it could be either.
No. The AJ133 is a completely different engine design – new block, new heads, new timing system, new everything. They share only the "AJ" family name. Parts are not interchangeable.
The AJ133 (post‑2013) is generally considered the most robust, with the timing chain tensioner revision fixing the main weakness. AJ27 is also reliable but older. AJ26 and early AJ34 have more known issues [PATTERN DATA].
Technically possible but expensive – you'd need new engine mounts, a different ECU, wiring loom, cooling system, and possibly gearbox. It's almost always cheaper to buy a car that already has the AJ133.
A reconditioned AJ133 supply‑only is around £5,500–£9,000 [EM-QUOTE], plus fitting labour (typically 12–18 hours, ~£780–£1,170 at indie rates). Main dealer costs are significantly higher.
No SpeculationWhere a fitment year isn't confirmed, we say so - never a confident guess.
Cross‑ReferencedFitment data checked against multiple independent parts and specialist sources.
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