Hi All

New member here. I’ve just taken on this car as an unfinished project. This forum came up well for technical help and advice on my searches

What could possibly go wrong!?

I’ve looked at buying an XJR-S for the last 5 or so years but up until now other cars have taken my interest, so pleased to finally be joining the fold.

I’m based in the UK and the car is a 1992 XJR-S in Flamenco Red. It was owned by Jaguar Cars of Browns lane for the first 4 or so years of it’s life, probably a management car I’d imagine.

The engine is currently out and has been rebuilt by Brian Ball. There is other recent work such as a powder coated front subframe, new front shocks, new rear brakes etc etc.

I spent 1.5 hours looking the car over and could not find any real rust spots, went under the car, took all mats up, checked scuttle etc, there is bound to be something but hopefully it’s not a bad starting point. It’s also had a recent re-spray although not to a concours standard.

I was thinking of buying a car that was all together, but always wanted to put a manual box in and some other subtle mods so when this came up at sensible ish money I popped some brave pills and I will be slowly progressing the project.

So my plans:

1. Getrag 290 Gearbox and conversion parts from Simply Perfromance (I have lead on one but not sourced yet, might be tricky)
2. Ditch the Zytek Engine Management and go for an aftermarket ECU with coil packs. I can’t decide which one is going to be best. I fitted an Omex ECU to my 1966 Alfa Romeo with 2.0 Twin spark, that worked well but the local mapper/supplier no longer maps fuel injected cars as they claim they are sick of people bringing them badly installed stuff. Mine wasn’t a problem on the day i have to say, although the V12 is more complex and now we have a baby boy at home I don’t have as much time!!! Options are Emerald, Omex, Link and Haltech, of and ECU Master.
3. Wasted Spark Coil packs using Ford 6 Cylinder coil packs and will have to make up a trigger wheel of some kind, probably a 36-1. The Zytek equipped car does not have one sadly… (it’s in the Dizzy or on the flywheel i think)
4. Maybe go for broke and fit these sexy Jenvey throttle bodies if they will clear the bonnet. Jaguar V12 Throttle Body Kit 2 or maybe just stick with the standard 6.0 manifold and enlarged throttle bodies.
5. Tubular Exhaust manifold, either from Simply Performamnce or Custom.
6. Full Custom Exhaust back from the manifold; sadly probably with catalysts as this car is right on the UK cutoff…
7. New Veneers etc inside
8. And much more…

Anytips or advice would be much appreciated; what have people done for an aftermarket ecu, and has anyone fitted that expensive Jenvey manifold with Sucess?

That’s enough to for a starters, much more to come in the way of updates and questions!!

 

Sprintgtvgus,

Great car! A facelift XJR-S, well done!

And one that someone has already spent big money on, even better! That Brian Ball engine looks glorious, as with the front subframe!

You might want to look at the MoT history and maybe check the rear suspension for corrosion and wear as previously identified.

I assume it's had a no, plate change as I can't see history before 2016?

Great project, keep us all updated!

Good luck

Paul

 

Thanks

Yes basically It is the original reg was off the road from 2001 to 2020, there is logbooks and servicing and invoices to support that, seems to all check out but with a project I've tried to look the car over as much as I can I believe this is why there is no older online MOT history

 

Great project, welcome to the forum, lovely looking car. With a manual box the thing will be pretty fast too.

FWIW I say forget the tubular exhaust manifolds and Jenvey stuff. None of the exhaust manifold people I have asked have any, any at all, before and after dyno figures, and I deduce from this that their manifolds deliver bling but not go.

The Jenvey TBs will be great at high revs but will deliver poor low end and mid range performance. The OEM inlet manifolds are pretty good, and real performance gains can only be had by using the pre-HE heads and pistons, and even then up to about 4500/5000 rpm there is no advantage. Roger Bywater's book " Engine technology for the modern world" has a huge chapter on this subject which is really worth studying. The Aston Martin V12 - which is/was esentially two Ford V6s welded together - had an intake manifold almost identical to the Jaguar one you have. The difference in output is down to the valves, which is where the Jaguar unit is restricted at high revs, and the H.E. head cannot be modified much to fix that restriction. Hence TWR using the pre HE heads on their ETCC racing engine in the early to mid 1980s.

Depending upon funds, the Mobec system is the best plug and play kit you can buy,
https://mobeck.com/produkt/jaguar-v1...e-waste-spark/
but if you have the know-how those aftermarket makes you mention will do the job and far cheaper; but as I expect you know already, getting any aftermarket ECU setup to work really well in all conditions and loads is quite a job. But some guys I have heard about have used Emerald with great success so well worth speaking to them.

Either way, good luck and keep us updated!

 

Thanks

Yes the Jenvey Throttle Bodies are maybe excessive and there is a worry of losing torque, the runners are still a fairly good length by the looks of it, I’m also worried about bonnet clearance. Then there is the big cost of them!

Jenvey Jag V12

I think it’s the prospect of the sound and throttle response that excites me!

I guess the same could be said for a tubular manifold, I’m pretty sold on one of those as I think it’s a relatively simple way of optimising for a modest gain, more gains if combined with other modifications. I saw the Harry’s Garage vid where a 5.3 on Emerald Management and a 6.0 inlet manifold and a tubular exhaust manifold made 340bhp supposedly which seemed good, subtle tweaks to the 6.0 should give a reasonable gain.

I did email roger to ask if he fits intake trumpets to the 6.0 manifold but haven’t heard anything.

With the Mobeck kit I’ve emailed asking whether they can supply something for my car.

I do have a couple of concerns though, I read somewhere that the kit does not use a throttle position sensor? Which seems odd if that’s right?

Also there looks like only one wide and lambda probe, surely it should have one probe per bank??

I fitted and wired in an Omex 600 Ecu to my Alfa, wasted spark coil packs etc with some success, but that was when I had a lot more time on my hands. I did use a pre made loom which I adapted.

 

Yes, the system changed and you can only see back to 2007. If the car was off the road, that's why the first MoT shows as 2016.

Paul

 

A 6 litre engine should make about 330 BHP in standard trim. Sadly, Roger no longer offers the modified inlet trumpets.
I think Mobec's system can use a TPS but his kit does not use one as standard because of the poor quality of the Jaguar ones now available, and the speed with which even a good one goes out of adjustment. He does it on manifold vacuum, I think, but am not sure; but I am sure he will expain if asked.

I have very successfully fitted a Variohm Hall effect TPS, which provides a far more reliable signal (which undoubtedly a modern system including Mobec could use) and requires no electical setting once in place. This is the thread (though if your facelit XJSs uses the same TPS as my model I am not sure; but variohm can for sure supply whatever is needed as they program them individually):
https://www.jaguarforums.com/forum/x...engine-268012/

 

Thank You - looks like it’s a must to go for a Hall effect one really

 

Well, fingers crossed I have managed to bag what appears to be a good condition Getrag 290….

I did consider the Tremec TKK Route but that would be extra cost and I’ve driven a Getrag equipped car and actually thought the shift was quite nice and hopefully if it’s not knackered or abused the 290 will be stout enough….

I’ve also emailed @Mobeck Tekniske to see if their EFi kit could be adapted for my car as it looks like it could save a lot of time and hassle,
leaning towards keeping the 6.0 inlet manifold at the moment.

 

There was another very interesting book out there about the XJS in the Touring car championship series in the 80's. TWR did quite a few dyno runs to see about adapting their racing parts to a standard car to make a TWR version for general sale. For the most part, the racing parts only made more power from 6,000 to 8,000 rpm, and usually lost power compared to a standard car under 5000 rpm.

They found the biggest bang for the investment, was stretching the displacement to 6 litres, as the production intake manifold runners were too big for the 5.3. They kept everything else standard, including valves and cams and the 15% displacement increase gave a 27% increase in power. I think if you go to individual throttle bodies you would lose a great amount of low end torque and **** the power range up the rev band. For a road car you don't want to lose power in the 2000-4000 rpm range and only gain at 6000 and higher.

 

Usually the vacuum signal is used for determining the engine load and the TPS is used for determining acceleration enrichment. For acceleration, TPS is a predictive indicator, as when the throttle opens the ECU knows that there will be a need for accel enrichment, whereas vacuum is a lagging indicator, the manifold vacuum only drops after the load increases (and thus the need for accel enrichment) has occurred. With vacuum only the ECU would always be playing catch-up.

 

yes that is my worry. Although it looks like a TPS can be used.

 

I see what you mean, it’s not a modern 4 valve quad cam engine so would probably not benefit as much as other engines, at the top end and maybe losing in the mid range.

The main factor is the £4000 cost, not inconsiderable. The cross plane style runners of the manifold do have some length and then if there is space you have the option of trying different intake trumpets to give a longer runner length/more torque.

The manifold has mostly been fitted to fancy Restomod style E Types, and a few of which seem to have a 6.0, so I bet someone has a synopsis comparison/power curves that could be compared. E Type UK seem to do a lot of them?

I think tow 70mm (or whatever size larger than the standard ones) throttle bodies and enlarge the flange of the 6.0 manifold should be more than sufficient. The XJR-S air boxes and cold feed pipes on the facelift do seem like quite a nice setup.

Found a couple of photos of an XJS racer and then an E Type installation. Another compromise is that there is not proper air filtration, just a filtered gauze that from memory is quoted as 80 micron or not very fine.

 

All 100% true, and verified by Allan Scott's book on the car. I am not sure about your power increase number though; I think that the BHP increase was about 40 BHP on factory standard engines comparing 6 and 5.3 litre cars (ie about 14%). Though TWR did build one special 6 litre HE engine that made 400 BHP, I seem to remember Allan Scott writing.
I think that internally the factory version of the XJRS engine is identical to the "normal" factory 6 litre cars' engines. So I cannot see why Mobec's kit will not work; though if your car has something made by TWR under the bonnet, that is a different matter.
For reference Allan Scott's book on how they developed the engine is a really good guide to what is possible - using the non-HE original V12 flathead of course.

 

Thanks will have to give that book a look.

I also found this article about the E Type Unleashed, 400bhp and 396lbft from a 6.1 with the throttle bodies and a tubular header doesn’t sound too shoddy or unachievable.

E Type

it’s only £400k!?

 

BHP numbers above (say) 330 are really only achieveable for a tractable roadcar engine with the pre HE heads. This is the big difference in developing high BHP numbers between earlier and the later V12s. Mind you, from the writeup that E Type has loads of torque low down, but it is a flathead engine, remember. I do not think that the Jenvey intakes, lovely as they look, will work on an HE head as well as they do in that E type.
TWR, although their racing ETCC cars had HE badges on them and the pre HE engines were no longer manufactured or sold at the time, actually used the pre HE heads, which they were allowed to do because under the ETCC rules earlier variants were eligible. But as Jagboi mentions above, high revs are needed to make these numbers, even in a pre HE engine.
Huge BHP numbers have been made quite easily by people adapting and welding AJ6 heads (four valves, twin OHC) so that they fit onto a V12 block (the 6 cylinder engines were made on the same machines as the V12s). It is essentially the resticted valve area that makes the difference.

 

Ah, sorry I had forgotten that the E Type is a flat head…

The jaguar sport engine has a diffrent compression ratio and rating of 333bhp from the factory, I’m hoping with bolt ons and a custom ECU another 30-40bhp can be realised at least, most of all an engine that feels healthier anyway.

 

Hi

I get so many emails these days, did you send one to me? Did you get an answer? People are often called another name on email, messenger, whatsapp, forums and instagram and even they name is written Michael but call themselves mike on the phone. Its a mess :-)

I just finished a new 6 liter map a week ago. It came out amazing. I will make a video and show on my fb site

 

Apparently the standard throttle bodies can support fairly large HP numbers, that would be way down the list of things to spend money on.

 

Thanks, yes you just emailed me back.

Sorry wasn’t sure if the email had gone through or my email system had blocked it