XJS V12 Manual Conversion & ITB's & Maybe TWR Rep

[urquattrogus]

My first post here so please be gentle!

I've been plotting and scheming about buying an XJS for £10-15K and then modifying it tastefully.

I'd love a Lister XJS but that seems to be a little out of budget, £60K for a good one now it seems. I'd need to sell two other cars I like to get close to that.

These guys do a manual conversion:

https://simplyperformance.com/v12-5-speed-conversi...

I was then thinking of fitting individual throttle bodies and a fruity exhaust, no doubt at considerable cost. Perhaps run it using something like and Omex 710 ECU.

I have some experience with this as I fitted an Omex 600, Throttle bodies and twin coil packs to my 1966 Alfa Giulia, it's been great over the last three years.

The TWR rep bit I'm not sure about, I do idolise the 1984 TWR XJS, but I don't want to look too naff.

Has anyone driven a manual V12 XJS conversion?

I want to create something that looks and sounds mean but in a well thought out form.

Biggest question is, which car would be the best to modify? Engine wise there seems to be the Pre He 5.3 (too old and scarce?) HE 5.3, 6.0 TWR or the later Jaguar 6.0 unit?

Then there are different models over the years, eg the Le Mans special edition etc. Do some of them have a LSD?

Thoughts?

[davidr]

Hi and welcome to the Forum.
To go through your various questions

The Simply Performance manual conversion is well established and they've done many so you can have confidence. You could assemble the parts yourself and use their adaptor plate if you are more hands on.

If you are looking at throttle bodies, exhaust and ecu upgrade I would point you towards AJ6 Engineering and their PlusTorque kit. Thus will do all this for you and you can be assured that each component has been properly engineered and developed to work effectively together.

In terms of engines, the pre HE is generally considered the most tuneable. The post-1991 JaguarSport 6.0 litre had 338bhp stock which was the most powerful standard engine but they are quite rare.
The pre HE had about 275bhp and the HE 285 to 300 bhp depending on spec.

The V12 engine is magnificent and does most of its best work in the higher revs ranges. The standard 3 speed auto box doesn't really allow that part of its character to emerge but a 5 speed manual conversion absolutely liberates it and is a real transformation. A manual V12 is a quick and very driveable car.
Hope that helps.
Keep us posted on progress. This sounds like an interesting project.

[urquattrogus]

Thanks for the reply

Thinking about things more, It needs to be 1992 or prior as I don't want to have to run cats; performance and sound wise.

I quite like the Pre HE cars, but I think realistically a good HE might be the best bet and with the most cars to choose from.

I also found this (look at the price but wow!)

https://store.jenvey.co.uk/jaguar-v12-e ... ckjr04-kit

Whether that would fit under the low bonnet of the XJS I'm not sure, but imagine the sound a throttle response!

Simply Performance have a demo car so once I have sold my other car I'm going to go and have a look at that to give me an idea.

I've never had a JAG before, the two others that have tempted me a lot are the X308 XJR and the MK1 Saloon, both still on the list.

But for the meantime I'm after a Jag and I'm after a manual V12 which is quite scarce when you look at what else is available from other brands.

[davidr]

There were only ever 352 factory manual V12's. This is due to Jaguar discontinuing the option in 1979 due to lack of interest.
Anything you may find after that would have been converted. There are very few around.

[iRS]

Hi there,
A couple of things on this. I had a manual HE once. I bought it converted - I think it was a 5 speed Getrag - and then had Hyper Engineering go over it and fully sort it. I remember picking it up from them after they had finished at Bruthingthope aerodrome where a car mag was testing two other Hyper cars out. One a converted manual, the other a modded auto. Fast......That was a long time ago. The manual conversion completely transforms the car to such an extent it could be a different car.
That brings me to my second point. You could try looking for a 'Hyper' car. Some books on XJ-S's do mention them and they have been referred to as a poor man's Lister. However, awesome cars and even more rare. A fully sorted Hyper is well up there with Listers. Paul Hands is the guy behind Hyper. I've heard he's retired to Devon, but I believe he surrounded by XJ-S parts and some cars. You'll find him on Facebook where he occasionally sells parts. It might be worth a chat.

[RichardSEL]

Yes, Paul has retired from Hyper XJS that was near to Thame.
His partner Greg Phillips still is there though, well worth using
Same 'phone number 01844 278481
email gdpindependent@gmail.com

Paul did my first XJ8 Sport for me. It was good when it went in
Frighteningly good when I collected it
Wouldn't say what he did though...

[urquattrogus]

Thanks Guys.

All useful stuff!

I'm a little all over the place at the moment as the range is so broad, but the options seem to be:

Bag a nice He 5.3, actually prefer the interior of earlier ones, for example, I've spotted a nice 1982 one for sale.

XJR-S 5.3 - I actually quite like the bodykit.

XJR-S 6.0 Pre Facelift Attracted by the 6.0 engine but scarce and the price etc. Difficult to repair Zytek engine management, probably would replace anyway.

XJR-S 6.0 1992/3 Facelift - A couple that look good value but I don't like the rear lights as much and they look like the heaviest version.

Also what is the actual cut off for running a car with no cat's legally?

I thought it was 1992? Would a facelift 6.0 be legal with no cats?

Confusing things is whether you "pass an emissions test" with cats or not.

I've phoned Simply Performance and KWE Jaguar for a chat so far (what do they offer, advice one which car, know of any good ones) ; sounds like Hyper are another good bunch to call.

Of course if I find a car that is already manual converted that would be s strong buying argument if the rest of it checks out.

I have found this but it looks like a Japanese Import, a little odd:

https://www.brightwells.com/classic-mot ... 6th-march/

Oh dear, it's become an obsession already!

[PaulGover]

...
Also what is the actual cut off for running a car with no cat's legally?
...

I think the most recent MOT changes mean that if your car had a cat, it needs a cat.

[iRS]

I feel much depends whether you simply want a car to drive fast in or whether you want some special with investment potential. If the latter, then a pre-HE original factory manual or a specialised conversation such as Lister/Hyper or one of the other 'specials'. If the former, then the ex-Japan car could be a good bet. I've heard ex-Japan cars come back in tremendous condition, much the same as when new. - as long as its still in that condition now.....

Here's some photos I dug out to inspire you. These are from the day I mentioned above and feature 3 Hyper cars in different states of modification. Mine was the least modified.

Richard - great to hear someone else here knows Hyper. I've known Paul and Greg since 'Kidlington' days, when they used to be just along from TWR.........

[BigCatXJS]

Mine is a v12 manual conversion. Getrag 5 speed with a number of AJ6 Eng / Harvey Bailey mods amongst many others. She was converted in 2014 by Alders Classics whom have performed a number of these conversions now. 5 years on and the only issue I had was with the bespoke gear box mount that needed to renewed. It was bespoke due to having the two TT-pipes running either side of the Getrag box. No regrets - great touring car but still a bit of a handful on a circuit.

[urquattrogus]

This might be back on.

I've been to look at an '89 5.3 XJS with Marelli Ignition.

The car was already converted to manual using the Getrag 265 and appropriate rear diff.

Got a chance to drive it and it felt pretty good. AJ6 Exhaust and uprated dampers, springs and ARB. TWR bodykit etc.

It seemed to be in good condition underneath when on the ramp, lots of new parts, however most work done about 10 years ago and hardly used since.

Found a small amount of water in the passenger footwell but not rust holes, seems like a lot of XJS do leak?!

Anyway, for circa 14K (prob a bit less) it's tempting.

The thing is, I haven't driven an auto yet, particularly the facelift 6.0 XJRS that I fancied....

The manual car is nice but it's a standard HE with lots of mods (most of which i would do myself)

However, I can't help but wonder If I should pay more for a 6.0 XJRS or XJR-S and then convert to manual.

Might piss the purists off, and then would prob have to replace the Zytek engine manament on an XJR-S.

For both cars I fancy fitting emerald/omex and throttle bodies.

Is the 5.3 HE very Tunable? The Jaguarsport 6.0 has different internals etc.

Decisions decisions.

Part of me says buy the older 5.3 and finish it off, enjoy driving it hard, most of the expensive stuff such as box has been done.

The other part says buy a 6.0 as more special but I know that means more money to get a good one and less originality.

hmmm.....