Hi Guys
I recently fitted a good quality 10% overdriven pulley to my 2003 XKR. The engine is in good health. No codes thrown. Thing is I can't feel any difference whatsoever.
I've had a number of high hp cars and seat of the pants dyno is pretty good from years of drag racing. Any ideas on why I wouldn't be getting any benefit.
Any ideas greatly appreciated .
Cheers Jeff

 

Is that the blower pulley or crank?
l changed my crank pulley recently and difference is very noticeable.

 

It was the blower pulley

 

You should make sure your supercharger coolant pump is actually running. You should also expect some heat soak effect, but at least the first couple of pulls without a cool off period should feel stronger.

 

Thanks. How do I confirm this?

 

 

My understanding is that the pump is by the air box, and comes on when the key is in accessory position (engine off), so you should be able to hear it. I believe it is always on (not thermostat driven).

 

In that case the pump is definitely running. I do notice a small flat spot somewhere between 5000 - 6000 rpm on WOT. Wondering if maybe there's a fuelling issue or maybe MAF or O2 sensor?

 

If you haven't already clean the MAF and check throttle cable adjustment. Those two items make quite a bit of difference.

 

Thanks for that. I did that a couple of months ago.
Both needed doing. Happy to look at them again...

 

I changed mine and noticed an immediate difference. Just wondering if previous owners had changed it already? Id measure and compare. The point about the MAF is a good one too.

 

Check fuel pressure, it is available over OBDII. Should be about 55psi at all times. Change the fuel filter if in doubt.

 

Jeff390,

By the seat of your pants, You will not feel any difference with a smaller pulley on the S/C! There may be a little on a dyno but not enough to go to all the trouble of putting it on...….The one advantage of having it on there now is that you won't have to put it on again when you finally decide to go for the large lower Pulley...…..That's when you will feel the difference.... ! Guaranteed...…

Billy Clyde in Houston

 

there is a diff in the upper pulley. generally 1.5-2.5 psi added boost. however not only more boost but it brings the boost in sooner. you should feel it. unless your butt dyno is just old and no longer accurate or calibrated.
just add the lower pulley now and be done

 

If a 2003 is similar as my 2008 xkr Any change in intake or exhaust is accounted for and included in factory programing.
There is an exact map with supercharger pulley size in the programing that I had to change when upgraded my pulley, Same applies for any exhaust modification, there is map written for exact backpressure. I can tell you guys that with mods and no tune and mods and a tune is a night and day difference , as if extra 100lb of torque was added

 

Does anyone know if the 2003 is the same as the 2008 as per the above.
I have also removed the back boxes on the exhaust as it was just too quiet. This will have altered the back pressure as well. I'm now wondering if I need a custom tune to realise the benefits..?

 

It's not, a 2003 has a totally different engine management system to a 2008.

If you're not feeling any changes from a pulley on a 2003 then you've got other issues holding it back, maybe choked cats, maybe fuel restriction, the standard intake on the X100 is also quite restrictive.

 

I really cannot understand that. I too have a 2003 XKR and I certainly can feel the difference. Not dramatic but its there. If your cars demand for fuel or air is restricted in some way then if the Supercharger asks and the fuel/air system cannot supply then that could be your problem.

Personally I would try the following. If its the original MAF change it. Dead easy to do. Takes 2 or 3 mins tops. Fuel filter if its been on there a while change it. Air filter same. While we are on the subject ...... Open up the air filter box, just flip the clips with a screw driver. Remove the paper air filter. Take a look inside. On the edge that is closest to the engine you will see a spring loaded flap, side mounted. Ensure that is free to move and is not stuck open or closed, normal position is closed. When you put your foot down, know as WOT (Wide Open Throttle) the engine management senses this and opens that flap to let more air in. If it cannot open you get less air therefore less power. Id spray it with WD40 to free it then grease it or oil it to ensure it stays free.

If you need a 'how to' on any of the above just ask and I will send you a link. Personally id try the MAF change first, there are non Jaguar MAF sensors which are much cheaper and are exactly the same.
Here you go. Take a read https://www.jaguarforum.com/showthre...l=1#post780676 and https://www.jaguarforum.com/showthre...l=1#post940168

 

Thanks Frank. I've had the MAF out twice and cleaned it with CRC MAF cleaner. I replaced the air filter element with a K&N one. Also replaced the fuel filter. Will now start looking into fuelling to make sure it's not being starved at any point.

appreciate your feedback .

 

Jeff390,

You will never get the feeling you are looking for with just the smaller upper Pulley......It's just not there! You need to go to Eurotoys.com in Chicago. Get their $995.00 Crank Pulley Kit, which gives you everything you need to increase your boost enough for you to get what you are looking for..."Torque" buy that Kit and also get the large Intercooler radiator and the large Water Pump, while you are at it......Then get a Snow Methional/Water injector system (Stage 2) with the VC-50 Controller....This will keep the system Cool, increase you HP & Torque and make you a happy Guy! Guaranteed! Rather than having 390 after your name, you will have to change it to about 430 or so!

Billy Clyde in Houston