Differences between XJS and XJ12 6.0L V12 engines?

question started when looking for crankshaft damper options, as the 6.0 are not common here on XJS, while sedans are less thought after
I 've done a search and didn’t find a list of differences between those engines, apart from the obvious peripheral constraints : engine mounts, air box and exhaust (?)

I’ve seen the ignition change from dual coils + Marelli distributor to Denso dual 6 pack from 1995 to 97
I also found a thread suggesting a change in crank (cast instead of forged on the late 6.0)
any other changes ?


There is also a change to the A bank camshaft and a sensor in the A bank cam cover. I assume it’s for the Nippondenso system.

thanks for this
it makes sense as the new ignition system would need the sensor + trigger on the camshaft

iirc, there was also some change on the crankshaft / crankshaft damper to fit a trigger wheel

You can find all of the changes in the document at the link below.
95 X300

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thanks Jon : that’s the full list
impressive how many changes came in with the new Nippon Denso system
Jaguar even took the opportunity to change the multiple belts to a serpentine

It’s more marketing fluff than technical, but here is Jaguar’s 6.0 introduction video:


I am very surprised at how many significant changes were made to the V12 in the last couple of years of production. Going to the Nippondenso engine management had to have cost a lot of development money, and was only used in the XJ12. It might have been the only way they could make it OBDII compliant, but I’m surprised they went to the trouble for so few cars, especially for the US. I don’t see how they could have recovered the development costs. It’s almost like they thought the V12 might continue being produced for a few more years.

I wish my so-called 1995.25 XJS had the Nippondenso system. While my car has the 16 pin OBDII connector, the protocols are not OBDII compliant. The only scanner that can read the diagnostic codes of all the systems is the PDU; not even the WDS can do it. The WDS has a menu for my car, but it can only read the ABS. By contrast, the WDS can diagnose the XJ12 from what I’m told.

thanks for sharing the video : I hadn’t seen it before
as this is announcing the new 6.0L, it 's from 93 or so

My coupe is an early 6.0 (oct 93) and I raised the point as toying with the idea of getting rid of the Marelli distributor, by moving to individual coils.
The number of changes makes it clearly impossible witout massive work