www.jec.org.uk

Following on from annother topic i though i would stoke the fires a bit on the subject of the best engine for the XJ-S.
The V12 is a design classic, i studied it when i was being teached bout ngines.
It is still a remarkably good engine, but it is far too heavy by modern standards. The Spitfire replica mentioned on the other thread had one taken out to over 10 litres! The lister Storms had a reliable 7.5 Litre unit. Lurvley.
The AJ16 is a much more modern unit but even that is old hat now. But in an XJ-s it saves 120kg, and that makes a big difference to acceleration but also cornering and breaking.
Now at work (Jaguar Whitley) i spend a lot of time tweeking the current Jaguar V8's. Now, whilst the yank V8's are indeed splendid, the Jag V8 is lighter (more complicated) and more powerfull.
The other day we had an XJS in from the heratage lot, and i couldnt help noticing that a supercharged XK8 engine would fit rather nicely in there.
Now thats a project worth doing.
By the way, I write for a mag called practical performance car, one of the staff writers has an SD1 with a Rolls Royce Metior engine in, that the Merlin without the supercharger, only 850bhp from 27 liters but sounds wonderfull. And it now has an MOT!
This started me thinking, a merlin fits in an XJ12 (thats an interferance fit by the way). Time to search Ebay????

IMHO having run
5.3 V12HE - Super engine, but expensive to maintain and "a little" thirsty....
3.6 AJ6 - the Xjs gets a more practical and bombproof engine.....and
4.0 AJ16 - Good blend of power and weight
The AJ16 is the engine of choice............. IN THE XJS AS A DAILY DRIVER
Re SD1 with RR Meteor.......this was a tank engine (fitted to Cromwell, Centurion and Conqueror) so installation in this car is quite appropriate.
Only joking, Years Ago I had a hankering for a V8 Twin Plenum model but never got one.
BTW Meteor rated at 600bhp standard, (I think).
Regards
DH Dove

I stand corrected. But 600 is still quite 'sufficient' i would have thought.
My V12 XJ-S regularly returns 25mpg on the run home to devon, which was reasonable pleasing. But i borrowed an XK8 from work one weekend and managed to get 34mpg average! now that impressed me.
The V8 has a splendid burble, but the V12 was one of the smoothes engines i have ever driven, although undoubtedly an old design now, it was however 'well' designed and still does what it was supposed to do.
There is a lot to be said for the AJ6/16 though. I think it better suits the handeling of the car and makes a significantly more usable package. Also its a hell of a lot easyer to work round!
I think that engine with a supercharger (as in the XJ saloon) would be a very nice car indeed.
For some reason i dont like the idea of putting a 'foreign' V8 in, although the Yank engines are undoubtedly good. I cant justify that dislike and wont attempt to, its just my preferance.

MORE THAN SUFFICIENT!
DH Dove

Not the best engine but certainly the most potent I had in a road car was a 455 c.i. Chevy, bored, stroked with nitrided crank, 300 bhp Cheater Nitrous injection, GMC 4000 supercharger and a pair of Holley 600cfm double pumpers with an Ibrok tunnel ram manifold with the whole lot exiting through 4-2-1 2" manifolds into a cherry bomb.

877 horsepower at the wheels but about 3 mpg round town and 9 on a run.

Always a trade off with power.

Wolf
Was it in a Mini?
DH Dove

A ton and a half of rust and filler masquerading as a 1972 Pontiac firebird. Then there was the axle swap and narrowing to hold the damm thing on the road. oh halcyon days indeed!