Hot Topic: Get 600hp Out of a 2008 Jaguar XKR
Sure, it might be an arbitrary number. But what Jaguar fan doesn’t like the idea of a 600-horsepower XKR?
The Jaguar XKR is a true modern classic. The stunning emerald green example in these shots was featured on the blog a few years back, and while the photos are truly spectacular, there really isn’t a bad line anywhere on the sheet metal. Plus, if you follow auctions? You’ll note that prices for these beasts — particularly the XKR-S versions — are starting to climb. That said, the stock 420 horsepower isn’t enough for some, and bamaboy473 is one of them:
Some of you guys have done amazing things to your cars and sing about outstanding HP gains. I’m 3 weeks into this XKR and out of a string of 911s, and would really like some kind of history of how to add an extra 50/100/200 HP to our cars without breaking either the bank or the cars. For discussion, can we focus on street HP instead of tracking?
Now, even in the horsepower-crazy world we live in today, 600 ponies is nothing to sneeze at. It was also, as the thread reveals shortly after, a fairly arbitrary goal. So after some members chime in, bamaboy473 starts thinking 500 ponies is a better target number. And as someone who appreciates nice round numbers and power, I like the sound of it.
That said, there were some folks with opinions on building a 600-horsepower XKR, though they require a pretty big pivot. Meaning, the first big upgrade he’ll have to make is the car itself, which was the suggestion from Stuart S:
If 600HP is your goal, save your money and sell your 4.2L 2008 XKR with 90K miles and buy a low mileage 5.0L 2010-up XKR.
You’ll need a limited-slip differential to put all that power to the pavement, and an E-diff is standard equipment on the 5.0L XKR. The 4.2L XKR did not come from the factory with a LSD, so you’ll need an aftermarket LSD from Quaife or from an old Lincoln.
The 4.2L and 5.0L engines are very different. The 5.0L has much newer and improved technology, including a much better supercharger and direct injection. You’ll never see 600HP out of the 4.2L, but that’s easily doable with the 5.0L with upper and lower pulleys and the right tune – and no internal engine mods. And don’t ask about headers – they don’t exist – or a cold air box. The factory intakes are as good as it gets, and spending more money will only get marginally better results. No real bang for the buck.
Personally, that seems like solid advice. I’ve driven that 5.0-liter mill in a few different cars, and it felt as robust as they come. So it wouldn’t surprise me if the relatively minor tweaks Stuart S suggested will do the trick. Here’s hoping bamaboy473 keeps the thread updated, and we get to see where he goes with this build!
Photos: Resident_fng; Boosted Photography