XJ6 & XJ12 Series I, II & III 1968-1992

How to Power Tune XK Engines - reprinted

Old 08-12-2016, 08:38 AM
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Default How to Power Tune XK Engines - reprinted

This title may be of interest to members running the XK straight six engined models. It has long been out of print and has recently been reprinted.

How to Power Tune XK Engines - reprinted-xk-engine.jpg

Author: Des Hammill
Title: How to Power Tune Jaguar XK 3.4, 3.8 & 4.2 Litre Engines
ISBN: 9781845849603

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Old 08-12-2016, 05:08 PM
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This is exactly what i have been looking for as the engine in mine is very low klm & i cannot justify pulling it out to lump it.
How do i get hold of it???????????
Old 08-12-2016, 06:48 PM
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I've read that book and it is very informative. From a historical perspective it's a wonderful look back on how tried and true hot rod techniques can also be applied to the XK engine.

As a practical matter, application of those techniques is not easy today. All the performance parts like valve springs, pistons, connecting rods, cam shafts, headers are no longer commonly available and would have to be custom made. Headers, one of the most critical components of a performance build are all but impossible to fit to a US car because the steering shaft occupies some major real-estate under 1/2 of the head.

Even back then results would have been marginal by today standards but back then marginal was good enough. Additionally, many of those techniques like a cam shaft swap cant be applied to a fuel injected XK unless one is willing to downgrade to a carburator or ditch the AFM and run a modern stand alone fuel injection system.

Practically speaking, for performance a lump is the only real option today. just about any low budget performance SBC build will be in excess of 350hp. And if you want more it's all possible. There is no amount of money or parts you can through at an XK that will get it down to the weight of an aluminium headed SBC. A sbc lump also has a much lower center of gravity. Weight is the key to any performance vehicle, it helps everything, breaking, handling and acceleration. Any one who has lumped can attest to that experience.

Last edited by icsamerica; 08-13-2016 at 05:47 PM.
Old 08-13-2016, 09:57 AM
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Originally Posted by Rickxj6 View Post
How do i get hold of it???????????
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Old 08-13-2016, 05:43 PM
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FWIW I can always pick a lumped XJ6 without lifting the bonnet/hood. The lighter lump changes the car's stance and it loses some of that low "prowling" profile afforded by the heavier XK engine. When mine is parked alongside a lumped car the difference is quite noticeable. Is it a big deal? Guess not, but I like the original low stance, and performance from the stock 4.2 is fine for my needs.

I could never understand why some owners strive to lower their XJ6, until now it had never occurred to me that on a lumped example it may be worthwhile to restore the front end.

Last edited by jagent; 08-13-2016 at 05:47 PM.
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