XJ XJ8 / XJR ( X308 ) 1997 - 2003

adding a supercharger to xj8

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Old Oct 27, 2008 | 10:35 AM
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red_ghost's Avatar
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Default adding a supercharger to xj8

So far I enjoy my jaguar, but my biggest regret is that I didn't buy the xjr. Would it be possible to install asupercharger on the xj8? What all would be needed, just a supercharger, the piping, intercooler, new belts and a new ECM? I would rather install a new one as I have already upgraded various things on my xj8 including dying the piping and some of the interior panels, new grilles, custom wheels (got rid of the old ones as one was leaking), custom exhaust, and subwoofers. I figure I would just get a twin screw supercharger right away instead of the Eaton.

How much more difficult will it be to install a supercharger on one of these as compared to something like a supra (a friend has one and he said it was very easy to install). I haven't had much experience with tuning as I've mostly been building lowriders and leaving my daily drivers stock. But I figure if I can make a cadillac stand on 3 wheels and a riviera hop 40+ inches, it shouldn't be that hard to install

Thank you in advance for the info.
 
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Old Oct 27, 2008 | 10:48 AM
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Default RE: adding a supercharger to xj8

Red, I think the one thing you will need to do so you don't blow up your project is to lower your compression ratio. Normally aspirated motors have a much higher compession than a supercharged or turbo motor.
 
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Old Oct 27, 2008 | 12:37 PM
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Default RE: adding a supercharger to xj8

Thats why I suggested the new ECM, or is it handled elsewhere? I'm sure I could just get it towed to the dealer for adjustment. Isn't the correct compression ratio 8:1?
 
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Old Oct 27, 2008 | 12:56 PM
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Default RE: adding a supercharger to xj8

your compression ratio has nothing to do with the ECM. when the piston comes upon the compression stroke it compresses the air/fuel mixture. on a reg. motor usually 9.5 to 11.5 you would have to modify the motor by
1 get a shorter connecting rod or
2 get smaller domed pistons
this will get you to 8.1 or 8.5

 
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Old Oct 27, 2008 | 03:27 PM
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Default RE: adding a supercharger to xj8

Sounds like this is going to be a bigger job than though. figure I have to remove the motor to do that^
 
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Old Oct 27, 2008 | 04:24 PM
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Default RE: adding a supercharger to xj8

You would be far better of selling your car and purchasing an XJR. Cost would be the same out of the shoot, but in repair costs you will save a mint.

Once you've changed it from the factory plan, mechanics will have to figure out what you did vs. what the problem is vs. how to fix it. You will pay for the extra time. Go with the factory original.
 
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Old Oct 28, 2008 | 12:08 PM
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Default RE: adding a supercharger to xj8

ORIGINAL: ken@britishparts.com

You would be far better of selling your car and purchasing an XJR. Cost would be the same out of the shoot, but in repair costs you will save a mint.

Once you've changed it from the factory plan, mechanics will have to figure out what you did vs. what the problem is vs. how to fix it. You will pay for the extra time. Go with the factory original.
Not like the old days when a carb rejet, highrise manifold & good headers would do the trick
 
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Old Oct 28, 2008 | 12:41 PM
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Default RE: adding a supercharger to xj8

Remember the days when you dropped a wrench while you were working on the engine and it would fall all the way to the ground?
 
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Old Oct 28, 2008 | 01:02 PM
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Default RE: adding a supercharger to xj8

Or anything for that matter, I lost a spark plug andnever found it because of all the plastic.Things were great you could actually see the motor. Today it takes an hour just to get all the plastic out of the way.
 
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Old Oct 28, 2008 | 08:09 PM
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Default RE: adding a supercharger to xj8

You could install thicker headgaskets (do they make metal ones for the AJV8?) to lower compression, but you'd need a good amount thicker than factory spec.

I think my headlight adjuster and spring for my leaper are still hanging out in the plastic underpanels......haha.
 
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Old Oct 30, 2008 | 07:13 PM
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Default RE: adding a supercharger to xj8

The tranny is different also, not sure if it would matter as far asgetting it to bolt in and drivebut from what I hear the XJ8 tranny is weak enough the way it is.
 
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Old Nov 2, 2008 | 08:38 AM
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Default RE: adding a supercharger to xj8

You don't want to know how much you will have to do to convert the motor, and it will probably set off check engine lights forever. The engine computer and tranny computer are tied to togther with a network and they must all be programmed to work together. In addition, as was said, the engine needs to be changed to get the right compression (cheaper than rebuilding it and engineering it to lower compression). It has been the opinion of most forums I am on that it is much cheaper and more satisfactory to buy an XJR.
 
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