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

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

Author
Discussion

lukeharding

1,402 posts

45 months

Tuesday 5th March 2019
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craigjm said:
I have driven a manual XJS and a manual XJC using both of the gearboxes common in use. The tremec T5 and the Getrag 265. They change the character of the car quite considerably. I have to say that the tremec in the XJC made it a totally different car and actually quite annoying after about 20 minutes of fun. It really took away the luxury cruiser style. In the XJS and the getrag, which was a simply performance conversion it was a different story but the clutch was quite heavy and again on a long distance drive I found myself wanting that bit more of an ability to just waft.

So for it XJC restomod I went down the route of a 6.0 TWR engine linked to a GM700r4 4 speed auto box using a Johns cars conversion and then fitting all of the AJ6 engineering modifications like the throttle bodies etc, quick cat air filters and by the time it’s finished it will have a switchable Emerald ECU and a ProFusion switchable stainless sports exhaust.

With this setup you can lock it in gear when you want to really hoof it and access all the power above 3000rpm and when you just want to waft lock it in drive, turn off the exhaust and take it out of sport.

Edited by craigjm on Monday 4th March 14:37


Edited by craigjm on Monday 4th March 16:56
Does sound like fun, and the ability to waft is certainly important. Even so I'd still be likely to have a manual as even over distance you're still in the same gear mostly unless you get caught in traffic and then I'll put up with the heavy clutch, its not something I am unused to really.

craigjm

10,784 posts

156 months

Tuesday 5th March 2019
quotequote all
lukeharding said:
Does sound like fun, and the ability to waft is certainly important. Even so I'd still be likely to have a manual as even over distance you're still in the same gear mostly unless you get caught in traffic and then I'll put up with the heavy clutch, its not something I am unused to really.
I live in central London that’s the main reason it was out for me. Stop start traffic with a heavy clutch is a big no

melhookv12

914 posts

130 months

Tuesday 5th March 2019
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Gus. I have a 6.0 litre genuine XJRS for sale.
I've converted numerous v12's to manual.
Using Jaguar 4 speed with mods. Cos worth 5 speed.
Converted earlier cars to outboard rear brakes also.
I've had 7.0 litre lister engine, with 6 downdraft webbers.

We've raced about 3 xjs' so I know my way around them.

Let me know if interested in buying the car. It will come with my phone number so you can ask me any questions along the way.

urquattroGus

Original Poster:

1,264 posts

146 months

Tuesday 5th March 2019
quotequote all
melhookv12 said:
Gus. I have a 6.0 litre genuine XJRS for sale.
I've converted numerous v12's to manual.
Using Jaguar 4 speed with mods. Cos worth 5 speed.
Converted earlier cars to outboard rear brakes also.
I've had 7.0 litre lister engine, with 6 downdraft webbers.

We've raced about 3 xjs' so I know my way around them.

Let me know if interested in buying the car. It will come with my phone number so you can ask me any questions along the way.
Thanks, I've emailed you via PH.

lukeharding

1,402 posts

45 months

Tuesday 5th March 2019
quotequote all
melhookv12 said:
Gus. I have a 6.0 litre genuine XJRS for sale.
I've converted numerous v12's to manual.
Using Jaguar 4 speed with mods. Cos worth 5 speed.
Converted earlier cars to outboard rear brakes also.
I've had 7.0 litre lister engine, with 6 downdraft webbers.

We've raced about 3 xjs' so I know my way around them.

Let me know if interested in buying the car. It will come with my phone number so you can ask me any questions along the way.
A 6.0 XJRS that has been converted? or still an auto?

lukeharding

1,402 posts

45 months

Tuesday 5th March 2019
quotequote all
craigjm said:
I live in central London that’s the main reason it was out for me. Stop start traffic with a heavy clutch is a big no
Yep can't blame you for that!!

XJR500bhp

1,122 posts

166 months

Sunday 10th March 2019
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Swallows Jag Bristol are just finishing their stand alone v12 ECU. They’ve already sold a couple

craigjm

10,784 posts

156 months

Sunday 10th March 2019
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XJR500bhp said:
Swallows Jag Bristol are just finishing their stand alone v12 ECU. They’ve already sold a couple
Interesting.... have just sent them an email. Maybe be a an alternative to me using an emerald unit. Look forward to hearing what they say


GiveItSomeWellie

2,865 posts

152 months

Monday 11th March 2019
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I'd love to convert my XJR-s to a manual one day.

Look forward to seeing progress on this thread.

geeman237

822 posts

141 months

Thursday 21st March 2019
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urquattroGus said:
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?
Have you checked out KWE Jaguars? Might be worth calling Chris there to discuss your needs. Nice chap and they live and breath XJS's. I had a 1994 XJS 4.0 coupe with a manual gearbox (v v rare in the US, maybe 100-200 sold). It was a nice car, but still more cruiser GT than sportier car. Never driven an auto version though.

craigjm

10,784 posts

156 months

Sunday 31st March 2019
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XJR500bhp said:
Swallows Jag Bristol are just finishing their stand alone v12 ECU. They’ve already sold a couple
Well I contacted them three weeks ago with a serious enquiry and no response, that doesn’t bode well. Think I’ll stick with my emerald idea and let Tom Lenthall do it

urquattroGus

Original Poster:

1,264 posts

146 months

Monday 1st April 2019
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I think it’s best to stick to something like emerald or Omex.

Omex supply KWE whom do a ECU set for about 5k.

No doubt this means ordering from an Omex dealer would be fairly straightforward.

I fitted Omex to my Alfa by ordering the kit and loom from a local supplier and fitting it myself. Then got the supplier to map it. Supplier was At Speed Racing at Rayleigh, they were good.

If you go for a more obscure ECU then there might be less support and know how out there. Of course there is always Motec and others but they might be overkill.

clouder

85 posts

140 months

Sunday 28th April 2019
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If it helps, I have driven Jon and Ben Thomson’s of Simply Performance 5 speed manual conversion (a Getrag 290) in an XJS and it transformed the car, great fun to drive (especially with the noise of the Performance exhaust encouraging you as well!).

urquattroGus

Original Poster:

1,264 posts

146 months

Saturday 15th June 2019
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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 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.....




craigjm

10,784 posts

156 months

Saturday 15th June 2019
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I have a jaguarsport 6.0 in my XJC with all the AJ6 engineering mods and a 4 speed auto conversion.

If your car is leaking water into the footwell then it means either the front scuttle or the bulkhead, or both is rotted through. Can you sneak fuel in the car?

urquattroGus

Original Poster:

1,264 posts

146 months

Saturday 15th June 2019
quotequote all
Can I smell fuel, no I don't think so.

Looks like I need to go back again to check the whole scuttle/bulkhead is not rotted!

300bhp/ton

38,779 posts

146 months

Saturday 15th June 2019
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Mine never leaked that I knew of.

I’ve not driven the 6.0 XJS-R, what sort of power did they make? Also apart from the displacement different, were the intervals all that different?

My XJ-S was an early (1982) 5.3 HE. It went quite well for what it was. My Dad had a factory 6.0 litre XJ12 (XJ40 shape) on a ‘93 plate. It had the GM 4L80e 4 speed electronically controlled gearbox. As opposed to the 3 speed TH350 in my XJ-S. Factory claim was something like 295hp vs 318hp iirc.

However the 6.0 was much more spritely. The gearbox certainly played a part in this. But it certainly made more power too. Just as smooth IMO. But a lot quicker.

craigjm

10,784 posts

156 months

Saturday 15th June 2019
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The Ford distributorless coil on plug 6.0 is 318. The standard 5.3 is 290, jaguarsport 6.0 From XJRS is 334 and the TWR 6.0 engine is 380

OTT532

5 posts

3 months

Sunday 17th May
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Great thread.
I had the exact same idea whilst on a 3 month business trip to Atlanta late last year. The business side of the trip was a complete failure.... but
the very day I got back to the UK, 17 December 2019, I drove to see a jaguar XJS V12 that I had been watching on Autotrader for a few weeks. I negotiated a price and paid the seller. The next day I returned to collect it and was so happy to be back in an XJS (my third). I have since been driving the car and covered 6,000 miles in her as my daily driver was stolen !!!
The XJS has been great, however, everyone I tell my plans to modify the old girl says no its too nice an example keep her original. A previous owner had lavished a huge restoration with KWE. I began to listen and believe that wafting around would be fine........ NO, the reason I bought this car was to put a 5 speed box, some other light improvements and an exhaust to highlight the 12 cylinders under her bonnet. So that is exactly what I am doing. My 25 year old Defender (stolen daily driver) was recovered and is now receiving a complete rebuild and very soon I will be driving her and it will be the Jags turn.
I am so excited and cant wait to take a very long holiday driving across Europe in her. Hopefully, Covid 19 will be under control and next August and September will be a mammoth European road trip.

craigjm

10,784 posts

156 months

Sunday 17th May
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Speak to Ben at Simply Performance for all you need for a 5 speed manual conversion