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Thread: x300 4.0l HUGE performance gains

  1. #31
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    wow it sounds a lot of work! well done
    please keep us posted on the progress... I am very curious to hear about the supercharged engine soon
    cheers

  2. #32
    Senior Member x300's Avatar
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    Thanks Rigajag,

    A lot of work indeed. The work is so extensive that I had to buy another cheap xj6 to use for a few months.

    I don't have the sovereign at the moment as it's getting the tubular manifold done and then the following week is the new rear subframe, rear brace and poly bushes. Can't wait to take it for another blast when it's ready.

    A supercharged engine would be the crowning glory, but it's a way off as the missus wants a new kitchen first!
    '95 x300 4.0 Manual Sovereign swb - Daily driver
    '95 x300 3.2 XJ6 - Running whilst my daily is having extensive repairs

    '97 x300 3.2 XJ6 Manual - Purchased only for the gearbox
    '96 x300 4.0 Daimler Six lwb - Restoring/weekend car - Completed and sold on
    '94 x300 4.0 Daimler Six swb - Was restoring but toooo far gone - now stripped and crushed
    '07 X350 2.7tdvi sovereign swb - Sold
    '90 XJ40 4.0 XJ6 swb - Sold - Moved to Austria

  3. #33
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    Sure can't argue with the lady kitchen comes first
    I am always amazed how clean the engine bay in any x300, I believe this is the sweetest straight 6 ever made and probably the most reliable.
    Emotionally I love (&I'm frightened of) the XK engine retired in 1987" can't help but looking at the temperature gauge more than the road... But the AJ16 in the X300 ...! can't explain why I feel so confident in this car..
    Amazing work please keep us posted & good luck !
    Cheers

  4. #34
    Senior Member x300's Avatar
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    I got the Sovereign back at the weekend, the tubular manifolds are a work of art:



    I'll try to get a video of all the work that was done soon, but first a cautionary tale - Do remember to check the condition of any underseal on your old Jag, as mine was last waxoilyed about 7 years years ago, so it had gone hard and lifted from the surfaces in places, this had allowed moisture in between the sealer and the metal with some scary results - this was one of the A frame mounts:



    This mount was completely covered in underseal so was covering what was happening underneath, looks like I caught it just in time, and the whole rear end of the car has been overhauled now. Bare in mind that my car has done 185k and is a midlands car, these mounts were in a very poor state.
    '95 x300 4.0 Manual Sovereign swb - Daily driver
    '95 x300 3.2 XJ6 - Running whilst my daily is having extensive repairs

    '97 x300 3.2 XJ6 Manual - Purchased only for the gearbox
    '96 x300 4.0 Daimler Six lwb - Restoring/weekend car - Completed and sold on
    '94 x300 4.0 Daimler Six swb - Was restoring but toooo far gone - now stripped and crushed
    '07 X350 2.7tdvi sovereign swb - Sold
    '90 XJ40 4.0 XJ6 swb - Sold - Moved to Austria

  5. #35
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    Quote Originally Posted by x300 View Post
    The wiring will be a pain as it requires constant 12v feeds which would be a lot simpler if the battery was in the engine bay. Anybody know where to get a constant 12v feed from under the bonnet please let me know, I was thinking about using the feed that goes to the current Fan relays, but they are hidden behind the front bumper so may be difficult to trace.
    Great project! Looking forward to more updates. Re the 12V feed, check the under bonnet fuseboxes, you'll find 12V there.

  6. #36
    Senior Member x300's Avatar
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    Cheers Katar83,
    Yes I did eventually realise that the fuse boxes under the bonnet contained a mixture of switched and constant 12v, so I have a plan of attack for the Davies Craig EWP install now.

    Unfortunately the car is laid up at the moment, on a recent week bombing up and down the A1 it used 5 litres of engine oil over 800 miles, the brand new custom exhaust is black with soot, as is the rear bumper, and no doubt the lambda sensors are totally fouled which would explain the rough running and stalling when up to temp, so it looks like after 188k miles the piston rings and/or valve stem seals have gone.

    Luckily x300 engines are very cheap, it was only after I bought one for £120 that someone offered me one for free. I'm having another 4.0l NA fitted in the next few weeks, and then I can carry on with other bits. I need to do more research into fitting an SC engine so cannot dive straight into that.
    '95 x300 4.0 Manual Sovereign swb - Daily driver
    '95 x300 3.2 XJ6 - Running whilst my daily is having extensive repairs

    '97 x300 3.2 XJ6 Manual - Purchased only for the gearbox
    '96 x300 4.0 Daimler Six lwb - Restoring/weekend car - Completed and sold on
    '94 x300 4.0 Daimler Six swb - Was restoring but toooo far gone - now stripped and crushed
    '07 X350 2.7tdvi sovereign swb - Sold
    '90 XJ40 4.0 XJ6 swb - Sold - Moved to Austria

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