XK8 / XKR ( X100 ) 1996 - 2006

Upgrading my XK8

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Old Today, 08:42 AM
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Default Upgrading my XK8


I Have all of this on it's way, it came off a wrecked car with 90k. It has everything from the heads up, except the wiring harness and coolant lines. Does anyone know if the XKR models have different internals? If so, can I use my internals, or would they cause issues? I know they have different compression ratios. Does anyone know based off of the pic if there is anything else that I will need to change from aside from possibly the fuel pump/adding a pump? Any advice or information is greatly appreciated.
 
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Old Today, 10:55 AM
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Pistons are different to name one important part.(lower compression)
 
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Old Today, 11:01 AM
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What year is your car ? The 4.0 XKR cars used a different MAF sensor than the 4.0 XK-8.

 
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Old Today, 11:14 AM
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For starters:

Pistons
S/C doesn't have VVT, (and your ECM expects them to be there)
Intake Air Temp sensor
etc., etc.

There are many differences. It may be a journey best not started.
 
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Old Today, 12:04 PM
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Getting past the high compression pistons and the VVT is not going to be easy no matter what one’s experience level
 
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Old Today, 12:15 PM
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Originally Posted by michaelh
For starters:

Pistons
S/C doesn't have VVT, (and your ECM expects them to be there)
Intake Air Temp sensor
etc., etc.

There are many differences. It may be a journey best not started.
Well.... The journey has already begun.
As far as ECM, I'm going to have it tuned to compensate for the upgrades. Possibly change ECM altogether.
I'm mainly trying to find out what parts I still have to purchase/change. I understand the size of the job, I just want to do it correctly.
The parts that are coming: heads, valve covers, plugs, ignition coils, intake, supercharger, fuel rail, injectors, throttle body, amongst some other parts. I can add more pics if needed.
 
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Old Today, 12:17 PM
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I would keep your heads with the VVT, you will need an XKR crank pulley to drive the blower and I would keep the boost way down like in the 5# range because of the compression issues mentioned above. I would be wise to get a boost-A-pump on the fuel pump (not sure that is an option on the 05) for some additional fuel. The factory computer should be able to compensate for the rest. You will also need to fabricate a pump and heat exchanger system for the intercooler, again not plug-n-play easy but not complex.

That is going to be a bigger project than it seems on the surface but the fun ones always are! Nothing you are doing to your car that cannot be undone if it doesn't work out (assuming you don't throw a rod or melt a piston!!)
 
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Old Today, 12:29 PM
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Honestly, my end goal, I'd like to get close to 500 HP. That's why I'm ok with changing so much.
 
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Old Today, 12:58 PM
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that is a big number on a stock high compression engine. You honestly may need to go to XKR pistons, at that point you are either rebuilding your block or swapping it out. If you swap it out you get the better pistons and oil jets (not sure the XK8 had them). It might we worth a discussion with a head gasket maker to see if you can have an MLS gasket made that is a little thicker to help lower compression. I am in the middle of building an engine and I will tell you first hand, to do it right is NOT cheap or easy. Forged Aston Martin crank ($ first born son), forged rods and oversized forged pistons ($5000), block work ($2000), head work (no idea, not there yet), gaskets, bearings and misc parts ($1500-2000).

Either way, document your progress for the forum, there some brilliant folks in our ranks. These cars are finally at the age and price where people are not afraid to push the limits.

 
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Old Today, 01:11 PM
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Originally Posted by Zach01
Honestly, my end goal, I'd like to get close to 500 HP. That's why I'm ok with changing so much.
suspension and brakes will need to be upgraded too.

 
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Old Today, 01:34 PM
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Originally Posted by Mjs128
that is a big number on a stock high compression engine. You honestly may need to go to XKR pistons, at that point you are either rebuilding your block or swapping it out. If you swap it out you get the better pistons and oil jets (not sure the XK8 had them). It might we worth a discussion with a head gasket maker to see if you can have an MLS gasket made that is a little thicker to help lower compression. I am in the middle of building an engine and I will tell you first hand, to do it right is NOT cheap or easy. Forged Aston Martin crank ($ first born son), forged rods and oversized forged pistons ($5000), block work ($2000), head work (no idea, not there yet), gaskets, bearings and misc parts ($1500-2000).

Either way, document your progress for the forum, there some brilliant folks in our ranks. These cars are finally at the age and price where people are not afraid to push the limits.
Exactly!! I love my car. I just want it to be able to scare the newer cars, not necessarily beat them. I'd like to think with a good tune, different pulley size and XKR internals I can get close to my target HP goal.
 
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Old Today, 01:51 PM
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Originally Posted by zray
suspension and brakes will need to be upgraded too.

It needs all four struts already. 😅😅 Brakes will come last probably.
 
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