www.jec.org.uk

As I am using my moneypit more and more, I am increasingly aware that the power is not exactly breathtaking. I suppose the weight of the 4 litre
engine is a factor and can see why many prefer the XKR (although not the new one ). What is the easiest route to obtaining a bit (well quite a lot) more power. Can a turbo be fitted to the XK8 without throwing away the aircon? Don't see many references to superchargers or chipping and I certainly don't want to start trimming the block etc. I just want it to get up and run instead of yawning when I hit the 'go' pedal.

Errr buy an XKR

TBH anything like fitting a turbo or charger is going to be soo expensive you may as well swap the 8 for an R.
Most easy mods will up the power by a few BHP, exhaust, air filter , re-map etc will net some increase but not up to R levels


You could always try nitrous

As Bassman says the most cost effective and easiest way of increasing the power of a naturally aspirated 8 is to replace it with an R. That said, I've always been irritated by the car's very high gearing rather than any lack of power. Most of the time, the high gearing deprives the car of the benefits of its quite reasonable torque by making the engine operate a long way below both peak torque and power points in the rev range. Jaguar's settings are good for top speed (were it not for the limiter!), emissions cycle tests and economy but they compromise real world performance. If these points are less important to you, why not try changing the diff to lower the overall gearing? Using a secondhand unit you should be able to gain an instant and very significant improvement for about £1000. Jaguar has done the same thing with the latest range of XKs compared with the pre 2006 models. In ordinary (sub 100mph) motoring the lower gearing makes them feel much perkier compared with their predecessors and has far more practical effect than the marginally lighter weight trumpeted in the press hand-outs for current models. Mike.

Good suggestion, Mike

I've bought the wrong animal!!! But the diff. sounds an unusual but effective route for that money. I don't think it needs much, just "satisfying" as happens when I floor the Saab Aero (only occasionally of course). Helpful suggestion, many thanks.

Have posted this elsewhere, but found water in the ECU 'box' was influencing the auto box. Eventually became obvious when I limped back to the Jag. main dealer with hardly enough power to take the car uphill.
I was told this problem has been responsible for some autoboxes being replaced (in error!) by Jag. specialists. After drilling a small hole in the plastic box to ensure draining mine now feels far more positive and predictable, certainly the difference between and .

That's good news, and a nice little tit-bit of information to keep stored in the old grey cells just in case!

If you still hanker after a bit more poke you could replace the OE exhaust which has a restriction where it bends over a chassis part. It will also sound a lot nicer!

Where is the ECU box located?

The ECU is at the back left hand side of the engine compartment under a cover with a finger hole in it.
http://i184.photobucket.com/albums/x238 ... bonnet.jpg

thank's Mike,
the beast came with a straight through exhaust, (the noise is more Lion than Jaguar), but I think the engine now needs tuning to suit this. Much better after ECU mod, but still strangely stifled at mid rev range.