Best Plugs for Thor on LPG

MELBUTCH said:

Speak with Dave King Technical at Prins Southampton.02380 446467. He will be able help you out.

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Thanks for that, I'm at my wits end with it. Will give him a call. It's just annoying as I paid top price to get a Prins system and 6 months later still not sorted!

It's on a Thor engine. I've had 2 3.9's on LPG in Disco and classic guise. Both single point Italian systems both over 10 years old with no problems!

It sounds like your problem is not the plugs.

Platinum is not a great conductor but a very hard and dense metal so plugs are expected to last, silver is the most conductive.

I would not use either since the copper £15 a set wammers pointed out are ideal.
ngk bp6es and will provide more spark energy than platinum.

at 250 miles to 90litres, the economy isn't going to improve. Was it the magnecor leads that started the problems with running and your installer?

When the car went in it had standard leads and NGK BP6ES plugs fitted.
Picked it up all seemed ok for about a week, then started misfiring above 3.5 K.
Changed the leads to Magnecor, took it back for a retune. Drove better but still poor mpg and would miss fire above 4K.
Was told that I should fit platinum plugs as that's oem equipment.
Decided to fit these Silver Brisk plugs, took it back for another re-tune and the garage leaned of the mixture. I now can use the entire Rev range but still getting less than 12 mpg and down on power.
That's a reduction of 40% on gas as same daily driving I can get 20mpg on petrol no problems.

I think I'm going to have to pay to get another garage to look at it as much as it pains me after shelling out nearly 2.5 grand to this other garage I'm not sure they really know what there doing but I'm helped as I've paid for the conversion now!

Modern leads are carbon cored and have built in resistance. Modern plugs also have built in resistance. That is why you don't need suppressors on plug leads anymore. This can cause a yellow spark if the old leads are breaking down or the coils are a bit iffy, which is no good to man nor beast. Plat coated plugs don't give you a better spark they are just more heat tolerant and supposedly wear resistant.

PastyMuncher83 said:

When the car went in it had standard leads and NGK BP6ES plugs fitted.
Picked it up all seemed ok for about a week, then started misfiring above 3.5 K.
Changed the leads to Magnecor, took it back for a retune. Drove better but still poor mpg and would miss fire above 4K.
Was told that I should fit platinum plugs as that's oem equipment.
Decided to fit these Silver Brisk plugs, took it back for another re-tune and the garage leaned of the mixture. I now can use the entire Rev range but still getting less than 12 mpg and down on power.
That's a reduction of 40% on gas as same daily driving I can get 20mpg on petrol no problems.

I think I'm going to have to pay to get another garage to look at it as much as it pains me after shelling out nearly 2.5 grand to this other garage I'm not sure they really know what there doing but I'm helped as I've paid for the conversion now!

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I wouldn't expect to get more than 13 on gas with a single point system on a 4.6, but then again I wouldn't expect to get 20 on petrol.

Having re-read your posts, do you think the garage are using the magnecors as a bit of a get out? If so, buy a new original equipment set and stick with the bp6es they started with and tell them to make it run sweet.

I only run hotwire efi, but the misfire sounds like your spark is too late or Missy so the new leads were worth a shot
You don't have a distributor on Thor so it's up to the sensors and ecu. Try posting in the v8 section. Someone here will know the answer

It's a Prinns VSI multipoint system, arguably the best system available, certainly the most expensive! Maybe they are using the Magnecor leads as an excuse, now it's the spark plies apparently.....
I'm getting about 200 miles from 80litres of gas, on my daily commute 20mpg on petrol has been consistent for the 4 months before I had the conversion done.
I'm going to take it to another LPG installer and get them to have a look, it maybe up for sale soon as looks like my commute maybe increasing and can't justify 12mpg even on gas

MELBUTCH said:

Speak with Dave King Technical at Prins Southampton.02380 446467. He will be able help you out.

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Hi Melbutch, can't get through to anyone on this number. Have u got an alternative one?

Thanks

PastyMuncher83 said:

Hi Melbutch, can't get through to anyone on this number. Have u got an alternative one?

Thanks

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It seems Lima Gas has gone commercial. They gave me a new number for Prins 01484 649100 contact name Mike Scott.
Good luck.

melbutch

MELBUTCH said:

It seems Lima Gas has gone commercial. They gave me a new number for Prins 01484 649100 contact name Mike Scott.
Good luck.

melbutch

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Thanks for that, I will give them a call.

I will be fitting platinum NGK's and then I've got it booked in at a different Prinns approved garage for them to have a look and see what's going on.

MELBUTCH said:

It seems Lima Gas has gone commercial. They gave me a new number for Prins 01484 649100 contact name Mike Scott.
Good luck.

melbutch

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Thanks so much for that it seems that it hasn't been installed correctly and hopefully I will get some resolution thanks to prinns' involvement.

I run a Thor with LPG, and just use the Standard NGK BPR6ES plugs, and Magnecore KV-85 leads. I have a Zavoli system fitted (most of the multi-point systems are much of a muchness in how they run though the setup/calibration can vary) and would get about 240 miles tops from 75L usable gas in it when I first got it.

I started having trouble with the injector wiring (system is about 7yrs old in the vehicle - fitted 4 yrs before I bought it) where there were breaks appearing in the pigtail from the injector to the plug to connect to the loom. I repaired one, and then a second one failed so thought I'd just replace the injectors. I couldn't afford a full set of new Zavoli ones (£45 each and then 8 of them!) so put some cheaper ones in (Valtek 30's) and while it runs ok, it's not great at all, especially under load. I tweaked the fuel map to give them a fighting chance, but even cruising at 70mph on the motorway, I could feel it being sluggish. The problem is the injectors just aren't good enough to run the system efficiently. I've now spent a bit on getting some new Hana injectors, which I'm yet to fit - but I'm hoping these will be faster to react and get it back to running nicely again.

Other things to look at are to make sure the gas rail pressure is high enough under load and that the vapouriser isn't under-sized for the engine size. Also if there is a gas rail filter (there should be) then it could be clogging up and restricting gas flow under engine load.

I think (from memory) my system runs at about 1.2bar - (I bought the cable and software for mine so I can monitor it). If the vapouriser is working properly, then it should be able to maintain that pressure even under load. It sounds to me like they've either used an under-sized vapouriser or injectors that are either cheap or have a slow response time - so can't deliver the kind of performance that is needed.

Hopefully the involvment from Prins will help get it sorted out soon for you!

Marty

Thanks Marty,

That's all good information. My prinns system is only 5 months old and has had problems from day one! Each time the installer has blamed the spark plugs!!

Prinns were initially helpful and diagnosed the fault over the phone after me talking them thru the install. It seems the garage I unfortunately took it to for the installation, which was "prinns approved"! didn't take the inlet manny off and just drilled into it in situ and tapped brass nipples into it that are piped to the injectors.

All 8 injectors are one the same side, meaning for the near side bank the gas has to travel almost 10" before igniting!!
Hence my lack of throttle response and poor mpg.
Interesting what you say about plugs, as after speaking with prinns they have confirmed the best results they have had are with the very same copper core ngk BPR6ES. I fitted a brand new set before I took it in for the install.
Then the garage blames them for being the problem! Either way I have lost complete faith in the "approved installer" that did the job and took 2200 off me.
I'm currently getting a second opinion on Friday, but as far as it goes for the minute I'm getting 10-11 mpg on gas compared to 20 on petrol. So although LPG is half the price I am no better off except I've lost a lot of power and am seriously out of pocket!
Prinns were initially helpful, but since speaking with this installer, who told him they'd done loads of intalls like this, without removing the manny and fitting the injectors as close as possible to the valves, they have backed down and asked me to get a second opinion at my own cost.

Either way, as you may be able to tell with this rant, I'm at my wits end and if something isn't sorted soon I will make my experience with a prinns kit and their approved installer widely known!

Where abouts are your injectors located? Did they remove the manifold to install them?
Another worry for me is where did the swarf go whilst they drilled thru the manny in situ?? Obviously into my cylinders!

I'm hoping for a resolution soon but it's not looking good!

I miss my 25yr old classic with its 10+yr old Leonardo AEB single point system, performed way better and returned way better mileage than this brand new cutting edge prinns Vsi system!

To be honest, I am not sure if they took the manifold off and drilled it out of the vehicle, or whether they did it in-situ.

I have heard of them being done in-situ before, and having vacuum there to suck the swarf out as it's drilled to stop any going inside, but I'd always take it off myself just to be sure!!

My injector inlets are in the lower intake manifold near the petrol injectors, and then there is pipe off the inlets going to the injectors, which were installed at the back of the engine (above the coil packs).
My vapouriser is near the EAS box (mounted on that shock turret) and then the gas feed goes out of vap, thru filter, then T's to each injector rail. the pipework from injector to the manifold is probably about 15-20cm long at the MOST to the front injectors.

Also one other thing that has caught a couple of people I know out is that there are a couple of the inlet tracts that cross over in the lower manifold, so the injectors need to be reversed. I have all the parts now to completely re-do my front end of the LPG gas side from the vapouriser - new filter, pipework to injector rails, and pipework from injectors to manifold, as I could see the old pipework starting to crack in a couple of places - so figured I'd spend the bit extra and completely redo it, so it'll hopefully be happy for the next 7 years!

One of the things that (when I was reading about LPG installs, soon after I bought my RR as I'd never had an LPG one before and wanted to know all about it) I read was that ideally you want the LPG injector inlets as close to the petrol ones as possible - and for all the LPG hoses from manifold to injectors to be as close as possible to be the same length, which it sounds like your install doesn't have, and will definitely cause problems on the bank which has the longer pipework.

Some places also don't tap into the lower manifold, but rather the upper manifold (the bunch of sausages on a Thor) which is relatively easy and quick to take off unlike the lower one - but situates the gas inlets further away from the petrol ones.

I've just had a look to see if I have any pictures of my install, but I can't seem to find any. I'll take a few when I get home on from work on Tuesday if you like (and I'll take some of the actual LPG inlets etc when I'm doing my work on them and replacing the hose work, as I'll be taking the upper manifold off to get to everything)

Post up a picture or few of your install if you don't mind?

Marty

Hi Marty,

Will post some pictures on the weekend, not enough light in the evenings anymore!

Yeah, winter/early darkness has been creeping up alright!!

I'm aiming to whip the upper manifold off mine tomorrow and get the LPG hose work all replaced, so if I get around to it (read if it's not p***ing with rain) then I'll take some pictures of the process/pipe work, cable routing, innjector locations and the likes.. If it's not tomorrow, then it might be the day after!

Marty

I'm getting ready to fit my prins LPG kit shortly got a full kit removed from a 4.6 Thor same as mine pre drilled manifold and wireing loom just need some Tees from the heater matrix hoses to vaporiser then I'm ready to go, oh and a new LPG fuel pipe from tank to engine bay previous pipe was copper and was cut is this what's best ??? Or is there something else ???

I use LPGshop.co.uk (no affiliation - just repeat customer) for all my LPG parts these days as they have a good range of bits which are in stock.

I think copper pipe is pretty standard for the run from tank - vapouriser, and some of it comes with a protective coating on it, so it's suitable to run under the vehicle. I think it has to be clipped every 20 or 30 cm from memory (might be different - check on this before installing it!)

Water pipes - I've had a few people say that it's best to run the inlet to the vapouriser direct from the heater feed - and then the output from vap to the heater core - that way you get a better flow through the vapouriser. Then the return from the heater matrix runs as standard. Mine is T'd in and seems to be fine - but I am considering changing my setup as I think I get a bit of air trapped in one of the water lines to the reducer - whereas if it was in line with the heater matrix, it would get pumped through, as at the moment there is the bypass for water to go straight to the heater matrix. I think a lot of it is down to personal preference though - it will work either way.

I'd look at getting Faro pipe for the run from the tank to the vap.
As it's a kind of plastic/ rubber it's more flexible and makes routing it a doddle.

T's for the heater pipes should be fine in most cases. Make sure you get the right size, Range Rovers have larger than normal heater pipes. I think it's 19mm but check.

Gas nozzles should be as close as possible (no more than an inch) from the petrol injectors. That's LPG installing 101. I've never heard of anyone putting all the nozzles on one side, doing that effectively makes your expensive multipoint system and single point system. It's easy enough to do, but you have to take the manifold off to do it. make sure you have a new valley gasket before you take the inlet manifold off, or you might risk coolant leaks on reassembly.

Leaving the manifold on is just stupid (but of course quicker). I have heard of people leaving plastic manifolds on for drilling, but aluminium ones should be taken off because of the swarf.

I like LPGshop too, there a place called Tinley Tech that are very good and helpful.

Yep I think looking at other installs I prefer to put the vaporiser inline as apposed in parralell as you say it will be pumped so much less chance of air locks.

Its a 2nd hand kit so iv got the inlet manifold sitting here tapped n connected to the injectors should just be a straight swop and the full wording loom with all connections made but I want to check how/good bad these connections were made I prefer all solderd n heat shrink my self

Well the approved place that did mine did exactly that and drilled into the manny! I paid top price for the install aswell?!

Also all 8 injectors are on the o/s bank so the gas going to the near side 4 cylinders has further to travel than the offside! I will get some pictures up of how not to do it over the weekend.

Prinns are still working towards a solution for me, but at present it looks like I'm going to have to fit the bill of getting the injectors fitted properly. I'm not at all happy about taking it back to the original installer as God knows what else they could do whilst it's with them.