A friend has been talking about converting his V12 to run on gas (LPG). Does anyone know if there any issues with running XJS on gas?

 

there is a guy on the UK stag forum that l think can answer your questions

sp_sparrow@hotmail.com

 

There was a kit available on ebay in Melbourne a while ago so it is doable. The issue is the size of tank you can get in an XJS is about 70l and will not give very good range.

My wife's Falcon is gas only and most of our driving is country the Ford gets 12l/100km on the open road and about 20l/100km around town.

 

The size of the gas tank which will fit in the boot of an XJS, combined with the amount of gas it will suck will restrict its range for sure, so I'm not sure that a gas only option would be great. Maybe a dual fuel unit would be best to make use of the standard petrol tank.
I was mainly wondering if there was inherent issues with Jag V12s and gas such as valves/seats or any sort of material issue in the intake, or anything else which would be a problem. It seems the amount of fuel a Jag V12 chews is one of its biggest complaints, so I would have thought more people would have run them on gas.

BTW Warrjon, I enjoyed the thread on your 6.7 litre build, it is giving me ideas.

 

I haven't been on any UK stag forums, but if it is about 14 point trophy red deer stags, I might be interested. I will email this person about any issues with converting Jag V12s to gas incase he is aware of any pitfalls.

 

I have seen a few V12s converted to LPG but I personally wouldn't. Most workshops wouldn't touch the V12 due to the lack of space and complexity...

 

So, other Jag V12s have been converted to gas, so maybe there is no inherent design/material flaw which negates its use, but yes, the available space is not idea. Not sure how much the V12 complexity will handicap running a V12 on gas..

 

These people are a UK specialist that have done lads of V12 conversions and have had numerous articles in the JEC mag. Dual fuel is a must, but the real problem I would imagine in many lrge countries like Oz would be places that sell the LPG.
K Mugglestone & Co
Greg

 

That is great to hear that there are plenty of others who have run XJSs on gas. No issues on my area finding places who sell gas, but no doubt if I go to some very remote areas, it might be hard to find.

 

If you want to use a fuel injectIon system (the better version) then that will involviert removing the entire intake assembly and drilling holes into that. If they drill installed, expect loads of aluminimm crumbs in the engine...

A venturi system would be the easiest way BUT is not effective and will not provide power and economy to make it work.

Being a 5.3l, you'll need two gas converters (to turn the liquid gas to gas gas) to run it right. Means loads of plumbing as it is fitted to the heating hoses... So they would be extended from the rear to the front to the rear again.

I just had my XJ8 converted in March to run on LPG. I went liquid injection with no filters and am rather happy... But doing the V12 is a no go for me. Just the wrong car to run on gas. If it was a XJ12, I'd say okay...

 

Yes there are V12's in Australia that are converted to LPG. Using vapor injection would be the way to go. Better MPG and power.

You will never re-couping the cost of the conversion in a vehicle that does not do high KM's.

My wife's car is a gas only Falcon and we travel from SW Vic to Sydney every month, this makes it worth having gas. I did consider it for my 6.7L but I would not get back the cost of the conversion in the cars life.

 

particularly relevant given the rip off level price we are forced to pay for our LPG Warren.

 

How high is the liter price down there? I pay €0.49/liter of lpg... My tank holds 40 plus intank pump. So a tankfill is a mere €20 and I get around 280 km out of it in daily driving conditions. Plus for every cold start about 0.1l of petrol...

My entire installation will have paid for itself in June... 14 months after fitting it... The liquid injection Vialle LPI I have cost for a V8 €3200... With installation, TÜV approval, bla. Instead of using 13l/100 km of petrol I am at 15l/100 km on gas... Can't complain at that. BUT it limits my topspeed. No more than 4000 rpm constantly making the XJ8 no faster than 200 km/h. But I normally drive around 2300 rpm (about 130 km/h).

Worst thing: Valve setting has to be done every 25k km so check Ing all 32 valves regularly is a must do.

 

In my area gas is around 60-65 cents a litre, so not to bad price wise. So it seems that if he wants to retain full power, which I am pretty sure he does, he will need 2 gas converters. He will have to see how much this will cost as it is looking like it will be more involved than the typical 6 or 8 cylinder.
I forgot about the extra valve adjustments needed with the standard valves. He might look into getting the seats and valves upgraded while it is apart but I would say he might just settle on doing regular valve adjustments if he did switch to gas.

 

Sydney LPG price is 10c/L more than Melbourne. I live in a small country town with 1 BP and we pay around 60c/L

Anytime you use the LPG converter power will be down. An LPG converter is just a LPG carburetor - totally mechanical.

My wife's BF mk3 Falcon is factory LPG only no petrol at all so Ford has optimised it for LPG. It has almost the same torque as the petrol but is down 30-40kw on the petrol, don't notice it until you hit the pedal to overtake.

The FG went to vapor injection and this makes a HUGH difference in power.

 

Absolutely. But then a vapor form gas injection will never be as efficient as liquid injection and it won't produce the power...

It will be a costly conversion and would take a long time to pay for itself... Especially with all the following costs... If you consider regular filter changes, valve setting, all the required labour and parts, etc I think it would be cheaper to stay on petrol...

 

I'll be converting my V12 in due course.

I was going to use 2x 6cyl vapour injection systems but when the time comes I think i'll just go the whole way & replace the ECU entirely with sequential control via Megasquirt or Haltech, & 2x 6cylinder Ford EDIS systems for ignition.

It's not a very complicated engine & with ~300hp spread across 12 cylinders it's fairly easy to convert with standard components. My last car I converted was a 280hp 4 cylinder turbo & that necessitated the best injectors available, high vapour pressure & 2 huge reducers to keep the pressures stable under load, none of which would be an issue on an XJS.

Liquid injection would be cool, but from what I gather the aftermarket liquid injection systems such as the Vialle LSI are very unreliable. They have an in-tank pump & proper fuel rail-type setup which i've read just doesn't last long. A shame as LPG vapourising in the inlet manifold rather than a coolant-fed Vapouriser has interesting performance benefits!
Did yours come with any sort of warranty Diam? It's been a while since I looked into it & they may have got better in the last few years

The nice thing about converting your car yourself is you can do it in small stages while keeping the car usable. I think I took about 4 months in total planning where to run things & fitting the tank/filler/fuel line/reducers/injectors/ECU & wiring in stages.. The Software used on many sequential systems is fairly intuitive & support is available, & nothing beats the feeling of that first successful fillup with a laptop on the passenger seat to check fuelling!

 

As said, I already run zmthe Vialle LPi... Works really well. Just a leaky injector issue...

 

Here are some good articles

AutoSpeed - LPG Vapour Injection

AutoSpeed - Falcon XR6 Turbo on LPG!

 

If anyone is interested in doing this. I have all the parts to do this conversion including the tanks and throttle bodies.