Jaguar 4.2 V8 Supercharged

[Legocar]

Hi all,

I'm new to the forum (and to lpg) so was hoping to pick up some info from those in the know.....

Searching the archives it looks like I've picked "a wrong 'un" for lpg conversion as many people seem to have had difficulties with the above engine (mainly premature Valve seat recession due to the softness of the valve material)....

However, at the risk of throwing good money after bad, I've decided that I still want to go ahead so I was wondering if anyone out there had had any experience with this and could perhaps "quantify the risk"?
There are always doom-mongers out there who will try to convince people that having anything done to their cars other than putting air in the tyres is likely to cause immediate and catastrophic failure and death!! I don't need this, I just want someone to say that they have knowledge of this particular conversion and can give an idea of the potential pitfalls.

Also, if anyone can recommend an installer in the midlands area who won't be afraid to take this job on, I'd appreciate it. I'm getting a bit tired of places that hear that its an S-Type R and don't return my calls.......

[richard_ha]

My dad just has his XKR (which I assume is the same engine) done, in Exeter I believe. I can find out who it was and let you know if you like?

[Legocar]

That would be good thanks, although a little further than I was planning to travel.

Today I stumbled on the Go-Lpg(.co.uk) website, which looked like it was exactly what I need..... an Lpg converter specialising in Jaguars, familiar with the 4.2ltr Supercharged engine and clearly not afraid of it.

However, whilst waiting for them to reply to my email enquiry I also stumbled across another site (lpginfo) that appears to have been set up with the sole purpose of exacting revenge on Go-lpg for a bad conversion job carried out a few years back!

Now I'm not sure what to believe.....
Go-lpg's site includes a number of disclaimers regarding things that can go wrong and whilst on the face of it, these could indicate that they care about the long term reliability of the cars that they convert, it could just as easily be an @rse covering exercise......
Can anybody shed any more light on this?

[Gilbertd]

A friend has exactly the same car as you fitted with a conversion. His previous X300 4.0 litre XJ6 had over 330,000 miles on it on gas when he sold it and his new one has done nearly 40,000 in the few months he has had it. I'll ask him what systm he has and if it is fitted with Flashlube or not.

[Gilbertd]

Saw my mate today. His car has a BRC system without Flashlube. Apparently, the 3 litre engine as fitted to the X type needs Flashlube but the 4.2 litre V8 doesn't. This place http://www.jaguarfuelconversions.co.uk/ are allegedly the experts when it comes to conversions on Jags, not cheap though.

[richard_ha]

It was this place....

http://www.gaspoweruk.co.uk/v3/index.html

[billynoband]

Most places quote much more for that supercharged engine and it's extended family.
http://www.gastech.org.uk/installgaller ... r_xj8.html

You should shop around and also speak to people who have the same car converted. Jaguar forums? Good luck.

[Legocar]

Thanks for the feedback guys.

The two outfits you mentioned are a little further away than I was hoping for so I decided to bite the bullet and try Go-lpg in Droitwich. I went to check it out on Friday afternoon and so-far-so-good.

Saw at least 4 other Jags in various states of conversion (all being converted for sale) and got to drive an XJR with a similar engine. No noticeable difference in performance between petrol and gas and the transition was absolutely seemless in both directions. The standard of fit and finish was excellent and the price was pretty much the same as another quote I had already received.

She's booked in for next Friday..... I'll let you know how it goes.

[lpg-jag]

I am looking at doing the same to a 4.2 XKR, whilst there have been the usual doom and gloom people, there does seem to be quite a number running the v8's both supercharged and not on LPG. Gaspower in exeter do keep coming up with very good reccomendation and talked alot of sense to me on the phone and have experience of the XKR, their price was competitive as well. However Exeter is a long way from Sheffield. I also had reservations about Go-LPG, and found the lpginfo site. I would be interested to hear your experiences as they seem to have the experience in converting jags. What system was on the acr you drove and what are you looking to have fitted.

I have also found a fitter in stoke who has a 4.2S type r who would do the job using Landi system and also the local jag specialist in rotherham does conversions but uses the single vapouriser OMVL system with petrol addition. The only thing that has stopped me going thre is the number of comments that insist on dual vapourisers for the supercharged engines. Any comments on progress would be very interesting

[mat_fenwick]

single vapouriser OMVL system with petrol addition. The only thing that has stopped me going thre is the number of comments that insist on dual vapourisers for the supercharged engines.

From what I understand the petrol addition comes in at high demand levels when the single vaporiser cannot supply enough gas. Part of me thinks it's a bit of a bodge, but at least they are being open about it. Better than selling you a system that isn't 'quite' up to the job of running the engine purely on LPG 100% of the time and leaving you to wonder why you're using more petrol than you thought! The other part of me wonders whether it's actually beneficial to have small additions of petrol when the engine is under the most load (valve lubrication etc)? Maybe one of the installers on here could give their opinions?

It would be very difficult to work out how much extra petrol would be used, as we don't know at what point you start the supplementary petrol injections, or how much driving time you drive past that threshold...

[Legocar]

The system proposed by Go-Lpg is a Romano HD. Can't find much info about it but apparently its a single vapouriser system that has been specifically designed to cope with high BHP applications (up to 500 or so).

Another installer I contacted spoke directly to BRC who recommended their twin vapouriser set-up..... but they would wouldn't they?

IMHO a system that has to either combine with or switch back to petrol to cope under heavy loads, just seems a bit of a cop out and clearly isn't up to the task. And surely to some degree it starts to negate the main reason for switching to lpg in the first place, if every time you squeeze the "grin pedal" you go back to paying full price for the pleasure?

I'll certainly post my progress during and after the conversion. With a bit of luck I can put some "demons to rest" and give some positive feedback regarding the installer, the equipment and the engine.....

[tommo2009]

it certainly isn't a cop out, 400hp is a high output, and under full load the demand for the gas is very large. Vapourisers and injectors have limits. as do petrol injectors.

The Bigas twin vapouriser is capable of 380hp and will cope with short bursts of more quite easily, but will the injectors flow enough at the top end.
The engine fitted to your car is very expensive to put right should it go wrong, so if it were me i would be quite happy to have petrol injected as well as gas should it be required at higher loads.

most of the time the vehicle will be running purely on LPG, it will only add petrol if you are driving it really hard, which negates the purpose of putting lpg on it. LPG is usually put on for economic reasons not so you can thrash the car.

These engines have a split tract inlet manifold with one tract to each valve, the petrol injector sits in a split in the tract which you can't do with an LPG injector.

What you could do to make sure the vehicle will have enough LPG at top end is to fit a 16 injector setup, this also gets around the split tract problem.

[lpg-jag]

From the comments from installers I think the petrol addition is from around 4k revs upwards, if this is the case then you only really go up into that range when dirving hard or for short periods of acceleration/overtaking. I would anticipate that probably 90% or more of the driving is below that limit and hence I am assuming that the economic reasons for fitting LPG will not be unduly affected. I have also wondered whether from a lubrication point that it may be a positive to have petrol addition under high load?

Hope the romano conversion goes well and that you can bring some positive feedback about the system and the installer.

[zenman63]

Do you have the jag back yet?
Post some pictures when you can.

[Legocar]

Dropped it off last Friday and was hoping that it might be finished today but no news yet

I did tell them to take their time tho, just to make sure that nothing was rushed and no corners cut, trying to meet a deadline. Still it would have been nice to have the Jag back in time for the weekend......

They have fixed a couple of other bits and pieces while they've been at it (mucky Air filter that should have been changed last service and a worn out supercharger pulley bearing) so I can't complain.

[zenman63]

Sounds all good, I almost took my last STR there but sold it !
I have a 2005 STR again now and still considering it, and like you I think steven is the guy at go-lpg.
I am looking forward to seeing your reply and pictures.

[Legocar]

OK, so picked the Jag up this afternoon and so far, so good.

All work seems to have been carried out to good professional standard and in terms of driveability, probably the best compliment I can give is that there is absolutely no noticeable difference between driving on gas and petrol. I switched back and forth a few times on the 30 mile drive home and the only way I could tell which fuel I was running was by looking at the LED's on the changeover switch

Unfortunately, during the conversion Steve noticed a pretty serious looking bulge on the inside wall of my front O/S tyre and so he'd been understandably reluctant to push the car to its limits during the set-up. I'll be replacing both front tyres tomorrow and then will take the car back for some real-time fine tuning to make sure that the fuel mix is correct across the rev range and under load. After that I'll be ready to give the car a good run to make sure that everything is as it should be.

Steve also showed me the Air Filter he'd replaced and to be honest its a wonder that the car was running at all beforehand. It was all caked up with an oily black substance like tar.... very nasty!

I'll report back when there is more to tell, but up to now its all looking good

[zenman63]

Bummer with the tyres, PS3 or Conti 3 are the ones to go for.
Good news on the lpg, please keep us posted and Pictures are what we need.

[Legocar]

I promised to update this thread with the progress of my conversion and I've finally found the time to do so.......

Unfortunately, its not all good news but nothing too terrible either. During the first few days after picking up the car, it started to alarm out and switch back to petrol under heavy acceleration. This got progressively worse as the tank neared empty but almost disappeared once I filled the tank. This turned out to be a big clue to the cause of the problem.
I took the car back to Go-Lpg after the new front tyres were fitted (ended up going for Vredestein Ultrac Sessanta and at the moment I'm loving them). Steve was able to track the problem down to insufficient gas pressure at the Vaporiser. A few quick turns of an allen key and the problem was resolved.
With me driving, he was also able to fine tune the gas injection profile, etc. to iron out a couple of very minor niggles I had with the power delivery.
I drove away afterwards much happier and started to enjoy the fact that my running costs were now significantly reduced without any loss of performance or refinement.
Unfortunately, my enjoyment was shortlived and that evening the gas system alarmed out again, only this time it was a different kind of alarm and it wouldn't allow me to switch back to gas without switching off the ignition first.
This started happening more and more frequently until eventually I was forced to run 100% on petrol.

I contacted Steve with a detailed description of the failure and we arranged for me to take the car back this morning. This time the Romano diagnostics software immediately identified a fault with the gas temperature sensor. This was unfortunately buried under the scuttle panel in the engine bay, but with some difficulty Steve was eventually able to replace the sensor with a known working one from another car.

This immediately fixed the problem and once again the drive home was a pleasure......

For now, all I can do is cross my fingers and hope that it was just a dodgy sensor and not a problem caused by the ECU, but either way I have full confidence in Steve's ability and willingness to resolve any issues that arise.

All the advise I read before getting the conversion done suggested that I should expect to make at least 2 or 3 trips back to the installer to resolve issues and for fine tuning..... so I'm happy to assume that this is just par for the course.....

I'll post again when I get the first 1000 miles under my belt and go back again for any final tweaks, but as things stand I can happily recommend Go-Lpg and although this installation in an S-Type R has been something of a learning experience for Steve, he clearly relishes the challenge and seems determined to make it a success. I'm sure the next customer who brings him one of these will benefit greatly from what he's learnt.

[zenman63]

Sounds good, any pictures of the install?