Jaguar v12

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3sGTE
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Jaguar v12

#1 Post by 3sGTE » Thu Feb 04, 2016 9:59 pm

Hello everyone.

I'm thinking of buying myself a v12 XJS. I thought it would be a bit of a fun project to own & obviously I will look to convert to LPG!
Has anyone ever converted one? Would the best way to convert be using 2 x 6cyl systems?
I'm looking at the 5.3 HE models up to around 1992.
I've read that the 5.3's are batch injected - does anyone know what impact this has in practice - can a regular sequential controller be used without issue? I used the LPGTech system on my previous car (sequential 4 cylinder) & have had good results with it, & found it fairly straight forward to setup, so would probably look to use the same again if suitable.

LairdScooby
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Re: Jaguar v12

#2 Post by LairdScooby » Fri Feb 05, 2016 3:38 am

First of all, i've never converted an XJ-S or even owned one, came close once but that was a lifetime ago!

If it uses full-group injection or batch injection then it's going to be hard to fit a sequential system i would think as to the best of my limited knowledge, the sequential systems are "slaved" from the OE fuel ECU to get the sequence correct. Without a sequence i would think you'd have 12 LPG injectors all firing at the same time.

Bearing in mind the V12 HE engine (from about 1982 onwards) is (i think) 305bhp, it might be an idea to run two separate systems with separate vapourisers and maybe a single point mixer per bank.

I could be wrong and it might in practice be just as easy to fit a sequential system and set it to inject all injectors to give full-group injection from just one or two petrol injector pulses - the installers on here will give you much better guidance on that.

This probably hasn't actually been that helpful for you but if nothing else it will give your post a bump so hopefully someone with a bit more knowledge of the V12 and converting it will find it quicker.
Cheers,
Dave


Somewhere in Suffolk with a Jeep, 2 Rovers and a V6 Volvo

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Gilbertd
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Re: Jaguar v12

#3 Post by Gilbertd » Fri Feb 05, 2016 8:24 am

Full group isn't a problem, there's plenty of Classic Range Rovers with the 14 CUX engine controller running multipoint systems and that runs full group. You'd need to use two 6 cylinder systems as nobody makes a 12 cylinder controller but it can be done. Alternatively, two single point systems will work with a controller per bank. I had a pre-HE XJS a few months ago but that didn't use lambda sensors, does the HE?

A mate had one converted many years ago but I don't remember what system was used. It was done by a company called Star Motors who used mostly Landi kit but they closed down many years ago. But there is a point to this. The guy I use for welding on the cars I import from the US is getting close to retirement and he recommended someone else that could do some work for me. Since then I have been using him and in the office at his workshop I noticed that he has his certificates on the wall and there is one from Landi issued to him. Turns out that he used to work for Star Motors and was the man that converted my mates XJS. So I can ask him what system he used as I know he will remember it......
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

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LPGC
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Re: Jaguar v12

#4 Post by LPGC » Fri Feb 05, 2016 2:06 pm

To take the pulsed LPG injection route, you could even get away with using a single 6 cylinder ECU (*of appropriate type), double up on LPG injectors (use 12, connect 2 to each channel of LPG ECU output) and run a Pitagora or similar to disconnect 6 petrol injectors. Not the best way but workable... * = must be capable or driving half usual LPG injector coil resistance

The best way would be as Gilbert said using 2 x 6 cylinder systems (which I do mostly on V10 engines in RVs etc). Even using 2 x 6 cyl ECU's and 12 injectors you could use 1 x reducer and 1 x map sensor (keep a sensor spare!) if you liked...

A very wide range of systems / components would give good results in both above scenarios.

This link will tell how to do it using 2 x single point systems ('back engineer' the text a bit!)... http://www.lpgforum.co.uk/viewtopic.php?f=28&t=13270

Simon
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Tubbs
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Re: Jaguar v12

#5 Post by Tubbs » Fri Feb 05, 2016 7:20 pm

:lol: As Simon says !
You can run them 'slaved' on a 6 cylinder kit. I've done one like that. And it worked fine. Big old lazy lump so it's not too taxing :lol:
Just get a nice big reducer.

marek
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Re: Jaguar v12

#6 Post by marek » Sat Jun 04, 2016 10:28 pm

I haven't checked the lpg forum for quite some time.

Your car is batch fired, in four groups of three injectors each. You car runs a Lucas 16CU controller, for which you can find plenty of data on the AJ6 website, just search for "Roger Bywater" to find it.

I have a fully sequential LPG and petrol system running on my e-type, also an HE engine, running for several years now without problem.

If you wish you can pm me or ask further questions.

kind regards
Marek

3sGTE
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Re: Jaguar v12

#7 Post by 3sGTE » Tue Jun 21, 2016 3:15 pm

Thanks for the advice chaps. I have bought the car now!

Decided to complicate things. Long term I'm planning on fitting a mega squirt ECU with Ford EDIS ignition.
So I can get the LPG up and running on the OEM ECU as well as allow it to be compatible with a future fully sequential megasquirt system, I'm going to rebuild the injection harness for fully sequential, adding splices to allow me to interface into 2x 6 cyllibder LPG ECU's, and patch this into the OEM Batch injection harness for now as I think it should still work?

marek
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Re: Jaguar v12

#8 Post by marek » Tue Jun 21, 2016 6:23 pm

You may be making more work for yourself than you really need to.

If you want to go fully sequential using Megasquirt, then it'll be by using MS3/3X or MS3pro. In this case, the MS3 will be easily be able to handle both the petrol and lpg itself fully sequentially and there is no need to bother with restoring the old ECU and adding twin 6cylinder lpg ECUs to get going.

I can give you some base software settings to get started and then you can let the ECU autotune itself via Tunerstudio.

kind regards
Marek

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Re: Jaguar v12

#9 Post by LPGC » Tue Jun 21, 2016 7:13 pm

Agreed with Marek's words on making work for yourself.

There isn't much of an advantage to sequential over batch firing, especially with LPG. Petrol can wet manifolds etc while LPG, which is a vapour anyway, cannot.

The only real advantage of sequential over batch firing can be very slightly crisper throttle response due to more accurate fuelling during acceleration but it would be difficult to distinguish between an ideally set up batch fire system and an ideally set up sequential system even on a 4 cylinder engine... and you're converting a V12. Marek will know more about MS3 than me - How easy is MS3 to set up for acceleration/over-swing type enrichment?

No reason why you couldn't fit 2 x 6 cylinder sequential LPG systems on the engine as it is (with the batch fire petrol injection system), modern systems will simply follow the batch fire injection methodology.

Hell of a quiet period on this thread between Feb and June, must just have been coincidence when Marek's post revived it!

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

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