Tech advises I should upgrade to the newer style serpentine belt for my 2004 XKR. I'm going to have the SC pulleys (maybe just one) changed out at the same time for some additional boost. I want more power but don't want to negatively impact reliability too much.

Any suggestions? Any suggestions on where to buy the pulleys? I hunted around the forum but didn't find anything specific.

Thanks in advance.

(Had to write this twice as this widget still blows up using Internet Explorer)

 

I own an 04 XKR. Jaguar designed it as a Luxury Grand Touring and did a superb job in balancing performance, comfort, amenities, reliability and safety. It's sexy, comforable responsive, and reliable. No it's not a Hellcat off the line nor is it nimble as a 911 and never will be no mater how much tinkering we do.

Jaguar Engineering spent gobs of time and money with a very well versed engineering team. When you change the pulley, what are you plans for adding sufficient cooling capability. What are the effects of using the stock exhaust with added boost? How will the Supercharger added RPMS effect bearing life? I wonder if Jaguar added modifications into the ECU program to allow for tinkering? My point is the Upper Pully mod may add a few percent of Boost but is really worth it ?

I'm leaving mine stock, it may be the last factory original survivor.

 

Ditto on "Stock" and the Grand Tourer comments RP. I don't race any more, but I do quite a few long road trips per year. What I needed was a GT: not a sports car. Your choice of the 911 for comparison is spot on - I would have chosen one of those if real performance was my priority. Our 390 ponies is nothing to sneeze at. When passing on side roads, slipping the J-Gate into "5" and letting the tranny kick down at WFTO launches the car to 100mph by the time I've completed the pass. Nice to have good brakes! - lol. And then I can enjoy the wonderful sound system, comfortable seats, beautiful interior and great ride again. Without a doubt she's a great GT! :-D

Agreed: Why P-off the reliability Gods when stock alone is so good?

 

Jaguar Tuning - Jaguar Performance Parts & Jaguar Engine Tuning


contact these guys, they were on wheeler dealers yesterday with mike and ed
by the way.

Me personally, would send the blower out to be ported with a pulley instal from the same shop and instal a lower temp thermostat, and YOU run a 60% distilled water to a 40%glycol mixture and bottle of water wetter in your cooling system. Guaranteed 38 MIN HP 2300-3900 rpms

The eaton we have is a horrible design that's considered an antique in performance shops and is only good for mid-range, at wot it produces such high IAT's, you lose power. I was at a local speed shop that has done some mods to xkr of our years.


I wish we could just throw on some rear gears, under drive pulleys and a better blower, but that's in your dreams(except for the blower), the engineers made sure to make this extremely hard on any tuning company as well as parts and retro-fitting.

 

I upgraded the lower pulley and installed a bigger intercooler radiator and higher performance intercooler radiator water pump. I also had the s/c inlet/outlet ports bored out, installed a limited slip differential and went to a 3.27 rear axel ratio. I am very happy with the results. I got everything except the LSD and rear end from EuroToys. They make fine products and will stand behind them if you have problems. Jaguar engineers were conservative and as long as you maintain you car, you won't have any problems.


Mark

 

I have a 3.77 LSD rear gear as well as a Kenne Bell Twin Screw, that is the way to go. All it takes is money.

 

I agree with the #3 and #4 leave alone/stock posts.
Some of the mods ruin the temperment of this refined cat and upset the smoothness.
Jaguar got it about right with the tweaks/improvements made to the 4.2 XKR.
Most modders are 4.0 owners.
The 4.2 is already improved beyond the simple 4.0 mods

Stands back and waits................

 

+1

 

'Right' is a very subjective measure in terms of car development. It was 'right' for the specific model year, and then next year 'right' shifted, and again the following year, and the year after, and so on. As to adding a few ponies with a pulley upgrade, do you honestly think that 30hp is going to upset the GT qualities of the car? Puleeez.

 

Having done these mods I can say that they in no way detract form the GT nature of my XKR. It is true that I have an 4.0L engine but the Eaton S/C on these cars was very conservative, with plenty of room for a little upgrade. One of the best mods I've done is the rear axel ratio change, which is not possible on the 4.2L XK8/Rs because of their ZF transmissions. Regardless, I don't understand why you feel such mods detract from these cars. What exactly are your concerns?


Mark

 

Small pulley changes will not make a big change in total power (but you will notice as it picks up earlier), and also not push you into the limits of the design (for normal street use), and last but not least, extra power doesn’t change GT into a sports car.

Having over 600 hp hasn’t made my car any less GT like (important quality for me as I drive a lot, am at 250.000 Miles), but it has given me an extra dimension of fun pending on how deep I press the pedal ;-)

 

a ported blower and pulley with some gears, is going to put a big smile on this guy's face ; ) 380 old, compared to 415Hp New

 

I wouldn't port the eaton its a waste of money. There is no documented proof it delivers anything other than more noise. If the latter is what you are looking for then go for it I would say.

Here are the only test results I know off that show a difference between a ported and stock unit under the same conditions:
Ported Eaton Dyno Tests

 

I run a smaller pulley and am very pleased with the results. No issues for me.

 

Interesting - I've been pondering this mod. PowerHouse claim +40bhp/Ftlb for their 2.5lb pulley mod at £400 inc fitting. A 10% power and torque hike for £400 sounds like a bargain, and I like the idea of a slightly quicker pickup as I find the XKR slightly "lazy" after driving RenaultSports.

 

How much $$$? LOL

 

Don't forget, in the UK, to factor in the increase of your annual insurance costs!! Any mods to an XKR will hit your wallet hard.



Well, unless your Renault was highly modded, your XKR must be in need of some checks.

 

I went with a larger lower pulley on my car because it is reversible. With the smaller upper pulley you have to grind the snout to be a smaller diameter. I don't really think there is any performance difference as the effect is the same, or at lease similar. Perhaps someone more knowledgeable in superchargers and engine mechanics can explain any difference between a larger lower pulley and a smaller upper pulley.


Mark

 

Who reports that to their insurance? Just a pulley and exhaust work...

 

ill be doing my lower pulley soon, I hope there will be a noticeable difference in feel and response. im tempted by 200 cell cats too