4.0 XJS....supercharged?

[theironduke]

I'm still beaming with my new toy but was recently musing about how one could go about giving the old girl more poke.... (yes, i know that buying a 6.0 V12 is the obvious answer..)

Anyway i was wondering if anybody has putted a supercharged lump from a XJR into an XJS? or fitted a blower even.

Is the basic lump in the 6 pot XJR's an AJ16 engine as per the celebration XJS's?

[a8hex]

Yes, the basic lump in the last of the XJSs is the same AJ16 engine as the X300 saloon.

For the previous AJ6 engines then there were some turbo modifications. If you hunt back a few years in this forum then Jagman (Chas from RGCs) made some comments about a Chasseur (I think) XJ40 mod, which he'd been involved with in a previous life.

I think with the AJ16 since Jaguar had produced the supercharged version people just worked on that as a basis.

[XKRacer]

I can remember an artical JWM some years back, I remember it saying you just cant bolt one on there are other things to consider, probably lower compression pistons.


You could always do what I did and drop an XKR engine in with a manual 6 speed viper box

[theironduke]

How much work would be involved fitting this in my 1995 (AJ16) Celebration car...

http://cgi.ebay.co.uk/XJR-JAGUAR-4-0-LITRE-ENGINE-...

[deadslow]

theironduke said:

How much work would be involved fitting this in my 1995 (AJ16) Celebration car...

http://cgi.ebay.co.uk/XJR-JAGUAR-4-0-LITRE-ENGINE-...

You should have bought the V12 6.0L.

[theironduke]

deadslow said:

theironduke said:

How much work would be involved fitting this in my 1995 (AJ16) Celebration car...

http://cgi.ebay.co.uk/XJR-JAGUAR-4-0-LITRE-ENGINE-...

You should have bought the V12 6.0L.

which produces less power than the above

[deadslow]

theironduke said:

deadslow said:

theironduke said:

How much work would be involved fitting this in my 1995 (AJ16) Celebration car...

http://cgi.ebay.co.uk/XJR-JAGUAR-4-0-LITRE-ENGINE-...

You should have bought the V12 6.0L.

which produces less power than the above

Good luck with the installation ;)

[a8hex]

theironduke said:

deadslow said:

theironduke said:

How much work would be involved fitting this in my 1995 (AJ16) Celebration car...

http://cgi.ebay.co.uk/XJR-JAGUAR-4-0-LITRE-ENGINE-...

You should have bought the V12 6.0L.

which produces less power than the above

I think people have claimed over 700BHP out of the V12, I'm not sure you'd get that from the SC 4L. The Lister XJSs were putting out about 550 and wasn't there a turbo charged one if you needed more poke?

[rswift]

I've often had this thought.....and I am sure it has been done, seem to remember an old jaguar World mag or similar. But I don't think it is a straightforward drop....and that '96 Celebration is about the most valuable version of an XJS, so I probably wouldn't want to butcher it.

The gearbox on the XJR was different I think, also the engine ECU would need to be sorted....plus...would the bonnet close ?

[rswift]

Found the article I was thinking of;

http://www.xj40.com/viewtopic.php?f=33&t=2065&...

[XKRacer]

Not once.....not twice....but 4 times

One problem with tuning V12s.......it costs £££££££££££££s Ask Bradley Smith

[theironduke]

To be fair i was only pondering, as had been said i don't think i'd want to mess about with my nice Celebration.

Maybe a silly tuned V12 one day

[Straight6DOHC]

There is a guy on xjr6.com fitting a xjr6 engine to his xjs at this time. It's been done before but as far as I know it isn't easy because of the security system and the ecm. One of the other forum users is developing hardware to overcome these issues.

[a8hex]

XKRacer said:

Not once.....not twice....but 4 times

One problem with tuning V12s.......it costs £££££££££££££s Ask Bradley Smith

That's just total engine pron!
but isn't chrome plating the drive to the superchargers a bit OTT?

The last supercharged XJS it saw had a single super charger sitting in the V.

Aren't the centres of the pistons cylinders the same on the V12 and the AJ6/16 engines? maybe you could combine the 2 concepts and fit a couple of AJ16 heads onto a V12 to get 48 valves and then ...

[theironduke]

XKRacer said:

Not once.....not twice....but 4 times

One problem with tuning V12s.......it costs £££££££££££££s Ask Bradley Smith

Is that a TWIN supercharged V12 i see beneath the bling???

How many horses does that beat make?

[robgee1964]

theironduke said:

Is the basic lump in the 6 pot XJR's an AJ16 engine as per the celebration XJS's?

Yes its the same basic engine, as the OP says it almost certainly has lower comp pistons in the supercharged version. You'd have quite a bit of work, you need access to a complete donor car as the way to go is swap the entire engine, along with engine management system.

If your lucky, it will be the same basic management system, you'd just need to change the ECU. Otherwise its a complete engine harness and ancillaries swap. Not sure about the exhaust but there's no reason why you shouldn't be able to do it, between the 2 lots of bits.

I fitted a 4.0 engine out of an XJ40 into a 3.6 XJS about 10 years ago, which involved the work described above. I remember being told at the time one sticking point can be getting the auto trans ECU to work correctly again, if the engine management system has changed. However my car was manual trans so no worries on that front.

To be honest there *could* be more mileage in simply doing a manual gearbox conversion, as all the 4.0 auto's I've driven felt rather strangled, compared to the manual versions. There's plenty of 2nd hand Getrag 'boxes around and they last forever. In manual form a 4.0 is pretty close to a V12, albeit not as smooth.

Edited by robgee1964 on Wednesday 25th August 14:29

[johnxjsc1985]

I was considering this with my 96 celebration but it was only going to give another 20 or so hp and it already goes quite well in sport mode.
The cost of doing it properly would probably be more than buying a half decent V12 and like you I dont really want to muck up my nice celebration. Doe smake you wonder why Jag didnt do this themselves though.

[robgee1964]

johnxjsc1985 said:

Doe smake you wonder why Jag didnt do this themselves though.

Maybe because they considered the XJS to be too close to its end to warrant the engineering effort. Saying that the supercharged engine was available in the XJ40 from 1990-ish. Perhaps they felt it might have killed V12 sales too. As you say it would have been a great car.

[Straight6DOHC]

robgee1964 said:

johnxjsc1985 said:

Doe smake you wonder why Jag didnt do this themselves though.

Maybe because they considered the XJS to be too close to its end to warrant the engineering effort. Saying that the supercharged engine was available in the XJ40 from 1990-ish. Perhaps they felt it might have killed V12 sales too. As you say it would have been a great car.

Although there were XJR xj40s, they were not supercharged. The first supercharged ones were x300.

[robgee1964]

Straight6DOHC said:

Although there were XJR xj40s, they were not supercharged. The first supercharged ones were x300.

Apologies my mistake. But it almost certainly made it a bit late in the day for the XJS.