How To Get More Power from an XJR
Additional horsepower from this high-performance future classic requires careful planning — and plenty of cash.
The Jaguar XJR is a future classic waiting to happen. It offers an experience that’s uniquely Jaguar — high performance and opulent luxury. One of our members, rufeo690, recently asked about adding even more performance to his 2006 XJR.
Stock, these cars make about 310 horsepower to the rear wheels — not bad at all. However, being a luxury car, that power has to propel a lot of weight — nearly two tons, in fact. A little more power could be a good thing.
He’s not flying completely blind , though. He’s read that exhaust mods and a twin-screw supercharger upgrade are the hot ticket on these cars. However, he still wants advice from our members.
Two members, jazzyjags and jackra_1, both chime in to say that a ported supercharger upgrade isn’t worth the cash. It’s best to save up for a twin-screw setup if you’re looking to go that route. there’s a considerable cost involved, but if it’s big power you seek, it’s your best bet.
Back to Basics
Of course, most XJRs are now hovering around a decade and a half old. In almost all cases, it’s best to ensure that your car is in tip-top shape before trying to extract more power. The timeless car forum axiom of “maintenance before mods” rings true in this case, as it always does. it’s a universal truth of performance car ownership.
The true path to more power isn’t always clear. In this case, the usual upgrades like intake and exhaust actually don’t offer the best bang for the buck. Like most forced induction cars, heat is a problem. Keeping the engine cool is a major concern, and is actually one of the best ways to improve performance.
The stock cooling system is very convoluted, and not particularly efficient. However, several of our members have been down this road before. They have solutions that both simplify and improve the XJR’s complicated cooling system. The first upgrade is an improved, higher-volume intercooler pump from Bosch.
Jackra_1 went all out with his cooling system. In addition to the upgraded pump, he also mounted an additional radiator a few inches forward of the stock unit, cooled by twin electric fas. He also uses a water/methanol injection system to keep temperatures down.
With maintenance taken care of and the cooling system upgraded, the usual bolt-ons will see their full benefit. Intake, exhaust, and pulley upgrades will add more power, especially when coupled with a tune. It may not be easy or cheap to improve an XJR’s already impressive performance — but it’s possible.
Photos: Jaguar Forums members
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