4.2 Supercharged LPG Conversion?

4.2 Supercharged LPG Conversion?

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Discussion

Mad Steve

Original Poster:

32 posts

207 months

Monday 19th December 2011
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Hi,

I currently run an '04 ML500 on LPG and so far it's been great. Only downside to the experience so far is that the ML does have s very bumpy ride and would love to change into something that rides on air. I would seriously consider a 4.2 Supercharged Range Rover Sport as it would have all the toys I love, a good turn of speed and an ability to haul a 16' tri-axle trailer which is a requirement!

However, I have heard quite a few horror stories regarding converting this engine to LPG, soft vale seats, heads going etc? Has anyone any experience with this engine on LPG or can anyone confirm or deny these stories? As always, I do value the expertise that does exist on the PH user forums! Looking forward to hearing your comments!

bozmandb9

673 posts

187 months

Tuesday 20th December 2011
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I'm on my second LPG converted FFRR S/C. The first is still going strong and is owned by a fellow forum member. I'm aware of a few which have been converted, and I haven't heard from anybody with direct experience of problems. It's certainly possible to mess up a conversion, on my first one it was a standard kit which didn't work well, it couldn't handle the power, so ran lean, or choked under heavy load.

However that kit was removed, and I got a BRC kit installed, which is more than capable of handling the power, and also has a BRC electronic lubrication kit installed, and it was perfect, had exactly the same kit installed on my second S/C. Now I don't really notice a difference when running on LPG, except it costs my £50 to fill up instead of £130.

I think the horror stories about the 4.2 S/C engine are way overdone, and mostly third party/ rumour. Perhaps there were more problems when the engine was very young and convertors didn't know how to get it right. Most problems I've read about related to silly things like not installing a fuel return line, or hacking into the fibre optic engine systems, or moving the air suspension compressor and not re-locating it sensibly.

Go for it, converted S/C = motoring heaven! See my carpool article on mine!

Phil.

5,131 posts

257 months

Wednesday 21st December 2011
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bozmandb9 said:
I think the horror stories about the 4.2 S/C engine are way overdone, and mostly third party/ rumour.
Unfortunately this is factually incorrect.

Boz, you appear to have had a reasonably good experience with the 4.2 S/C LPG conversion but even so it hasn't been without it troubles, so anyone considering a 4.2 S/C conversion needs to enter in to it with their eyes wide open! And ensure they use only a converter who can demonstrate they have successfully converted a 4.2 S/C to LPG and it is still running after a substantial period of time/mileage.

grand cherokee

2,432 posts

206 months

Wednesday 21st December 2011
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Phil. said:
Unfortunately this is factually incorrect.

Boz, you appear to have had a reasonably good experience with the 4.2 S/C LPG conversion but even so it hasn't been without it troubles, so anyone considering a 4.2 S/C conversion needs to enter in to it with their eyes wide open! And ensure they use only a converter who can demonstrate they have successfully converted a 4.2 S/C to LPG and it is still running after a substantial period of time/mileage.
very true

Boz views sc's and lpg through rose tinted specs!

bozmandb9

673 posts

187 months

Wednesday 21st December 2011
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grand cherokee said:
very true

Boz views sc's and lpg through rose tinted specs!
Of course, that's why I got a second one done! GC you're such a bore, why come here just to whine about Range Rovers?

Naturally most people considering a £15-20k car on LPG will go into it with their eyes open, which is why I spent many hours researching it before getting mine done! I spoke to many people with horror stories, but nearly all were based on 'internet wisdom', rather than actual experience. The owners I spoke to who had had conversions done, were very happy with them.

Anyway OP, I'm sure you'll do your homework, but I'm equally sure you'll appreciate feedback who's bought, and converted not one, but two, since if it hadn't been a good experience I would have been unlikely to repeat it, regardless of what eyewear I favour!


bozmandb9

673 posts

187 months

Wednesday 21st December 2011
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Phil. said:
Unfortunately this is factually incorrect.

Boz, you appear to have had a reasonably good experience with the 4.2 S/C LPG conversion but even so it hasn't been without it troubles, so anyone considering a 4.2 S/C conversion needs to enter in to it with their eyes wide open! And ensure they use only a converter who can demonstrate they have successfully converted a 4.2 S/C to LPG and it is still running after a substantial period of time/mileage.
No, it's opinion, hence the "I think", it's opinion based on many hours of research during which I found that most feedback relating to problems with conversions were based on rumour rather than experience, and many problems seemed to be related to incorrect conversions, I haven't found one actual real person who has experienced the problems relating to valve seat recession, though I'm sure there will be some.

Since you clearly know the facts Phil, in order to state I'm factually incorrect, how many engines have been converted, and of these how many have suffered valve seat recession?

Phil.

5,131 posts

257 months

Wednesday 21st December 2011
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bozmandb9 said:
I think the horror stories about the 4.2 S/C engine are way overdone, and mostly third party/ rumour.
Boz, you said the above which IS factually incorrect and misleading advice for someone considering converting a 4.2 S/C to LPG.

I was one of those people who had valve seat problems and if you check back we have had this discussion before on PH and the FFRR forums at the point you undertook your first LPG conversion, so either you have forgotten this fact or have selective memory.





Edited by Phil. on Wednesday 21st December 22:18

bozmandb9

673 posts

187 months

Wednesday 21st December 2011
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Phil. said:
Boz, you said the above which IS factually incorrect and misleading advice for someone considering converting a 4.2 S/C to LPG.

I was one of those people who had valve seat problems and if you check back we have had this discussion before on PH and the FFRR forums at the point you undertook your first LPG conversion, so either you have forgotten this fact or have selective memory.
Edited by Phil. on Wednesday 21st December 22:18
IF I preface a remark with the words "I think" then I am giving my opinion, not stating a fact. If anybody knows the facts relating to the number of conversions and the number which result in problems then please feel free to share them with us?

I'm stating my experience and my opinion, how is that misleading?

Edited by bozmandb9 on Wednesday 21st December 22:31

Mad Steve

Original Poster:

32 posts

207 months

Wednesday 21st December 2011
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Hi guys, the discussion has been great! When I bought my ML500 she hadn't been converted yet. I installed a Prinz system which was meant to be one of the best out there. It's been great, reliable and no noticeable difference in power. It was my local Prinz dealer who has advised me not to do it, turns out, Prinz don't do a system for the 4.2 S/C engine, so he maybe baised.

Looks like there has been good and bad experiences. If valve seat recession happens is it expensive to fix and or rectify? Can you prevent it? Will a flash-lube system remedy this? Also, bear in mind I do cover in around 30k miles p.a. and when I bought the ML a lot of folk said they were complete rubbish which the opposite has proved!

PS:- Let's not get personal and please keep the comments directed at mebiggrin

Many Thanks for all your help.

Phil.

5,131 posts

257 months

Wednesday 21st December 2011
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bozmandb9 said:
Phil, learn to read, if you preface a remark with the words "I think" then you are giving your opinion, not stating a fact. If you know the facts relating to the number of conversions and the number which result in problems then please feel free to share them with us?

I'm stating my experience and my opinion, how is that misleading?
Because it's factually wrong.

Phil.

5,131 posts

257 months

Wednesday 21st December 2011
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Useful link for the OP here

Boz, might help your memory wink

bozmandb9

673 posts

187 months

Wednesday 21st December 2011
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Mad Steve said:
Hi guys, the discussion has been great! When I bought my ML500 she hadn't been converted yet. I installed a Prinz system which was meant to be one of the best out there. It's been great, reliable and no noticeable difference in power. It was my local Prinz dealer who has advised me not to do it, turns out, Prinz don't do a system for the 4.2 S/C engine, so he maybe baised.

Looks like there has been good and bad experiences. If valve seat recession happens is it expensive to fix and or rectify? Can you prevent it? Will a flash-lube system remedy this? Also, bear in mind I do cover in around 30k miles p.a. and when I bought the ML a lot of folk said they were complete rubbish which the opposite has proved!

PS:- Let's not get personal and please keep the comments directed at mebiggrin

Many Thanks for all your help.
Hi Steve,

If VSR happens, I believe you'll need hardened heads, which JE do for £2,500 approx. My view was, worst case scenario if I needed the new heads, I'd have saved that in a year anyway, I may be wrong though! Electronic flash lube will certainly reduce the risk of VSR. I don't know if VSR can be proven to be related to LPG anyway, it would be interesting to find out how often it happens to cars without LPG.

I spoke to somebody who's got a converted 4.2 S/C with 170k on the clock, so far as I know it's still going strong after 3 years. If considering an S/C conversion, I'd say look at the power ratings of the kit and injectors to be fitted. The first kit fitted to my first S/C was patently not up to the job, and I can quite believe there could be many problems caused by fitting a standard kit which can't handle the 400 bhp, or supply enough gas. My BRC system has twin Genuis Max reducers, which can handle up to 480BHP, plus high capacity injectors, plus the BRC electronic lubrication kit.

Flash lube do an electronic kit, however it's known to go wrong quite often, a non electronic lubrication system will so far as I know be useless on a Supercharged car.

Main downside on LPG is range, I get 200 miles out of a tank, so around 13 mpg. Would probably be much better if I exercised more restraint on the loud pedal, but I exercise none!

bozmandb9

673 posts

187 months

Wednesday 21st December 2011
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Phil. said:
Useful link for the OP here

Boz, might help your memory wink
Hi Phil,

Thanks for refreshing my memory. Interesting that your problems were mainly related to the EML. This is a known problem in the 4.2 S/C, whether converted or not, if you doubt this try a little googling. My current S/C had it before I got it converted too! It is usually related to O2 sensors, I have the ability to read a reset fault codes at any time, it's certainly no more of an issue with the car converted.

I think this is a good example of LPG being blamed, where it's not necessarily the cause. Another one is gearbox problems, but again, this is usually down to low battery after the car has been worked on for several days, properly charge or replace the battery and the problem goes away, but many people blame the LPG conversion for a long time first!

So again, we still have no direct experience of VSR as a result of conversion! Good news!

P.S. Noted from your link of previous thread that you acknowledge that the RRS conversion is not usually problematic, that's the application MadSteve is looking at, not S/C Fullfat!


Edited by bozmandb9 on Wednesday 21st December 23:05

Phil.

5,131 posts

257 months

Wednesday 21st December 2011
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bozmandb9 said:
So again, we still have no direct experience of VSR as a result of conversion! Good news!
Take another look at the historical thread.

I had my valves replaced because they melted due to the LPG conversion. I didn't diagnose this, JE did. Fact.

As you know JE now require hardend valves are part of any 4.2 S/C LPG conversion - see here. Another fact.

Try Googling again wink





bozmandb9

673 posts

187 months

Wednesday 21st December 2011
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Strange, I re-read that thread twice, and you don't mention anything about melted heads, just EML issues. I can understand it wasn't a great experience for you, but CAALLMM DOWWWWNNNN!!! It's all over now, quite a long time in the past too!

I can also understand that it sounds like somebody cocked it up, then installed some hardened heads. Having cocked up your installation, they now try to sell their hardened heads to everybody, maybe they had to make up a batch! But I remember you telling me my engine would melt, and it hasn't!

Sounds like they fitted an inadequate kit if it was switching over to petrol under heavy load. The BRC kit doesn't switch back to petrol at all. The first kit fitted did, which was why I had it removed and replaced with a kit capable of powering the S/C.

So again, I say, get the right kit fitted by competent convertors, and it's not a problem.

Edit. Did find a passing comment relating to melted heads in your first post, but you didn't make it clear that it happened to you, in your post where you list your problems you say:

"It's not just about the heads, it's the set up that will cause most problems unless you are very lucky. "

Final edit. Done a little research. Switching to LPG under heavy load would indicate a system which cannot fuel properly with LPG (i.e. insufficient capacity reducers and injectors), lean running is known to cause the exhaust valves to burn out. Seems to confirm what I thought, and stated above.

PPS. Thanks, did google again!

Edited by bozmandb9 on Wednesday 21st December 23:21


Edited by bozmandb9 on Wednesday 21st December 23:22


Edited by bozmandb9 on Wednesday 21st December 23:32


Edited by bozmandb9 on Wednesday 21st December 23:33


Edited by bozmandb9 on Thursday 22 December 13:18

Phil.

5,131 posts

257 months

Thursday 22nd December 2011
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Finally we agree that an LPG conversion has the potential to cause valve problems particularly in the 4.2 S/C where there is a greater risk of it running lean due to the energy levels involved.

To the OP. If you are comfortable with the Engine Management Light (EML) coming on and needing resetting by the installer. If you are comfortable with financial risk of may be having to replace the valves at some point. If you can manage 200 miles betweeen fill ups. If you know how you are going to sell it etc. Then go for it. The point is, it's not a turnkey solution to solve all your economy issues. There are finacial risks involved and there will be at best teething problems with any new LPG installation on a 4.2 S/C.

My experience was over 18 months and 36,000 costing £6k. So I brokeven on the fuel savings but wouldn't do it again due to the problems incurred.

Here's an alternative for you to consider. Buy a TDV8 and have it re-mapped by a reputable organisation like JE and you'll average 25mpg with near S/C performance and plenty of miles between fill ups at any garage you happen to pass. Oh and no EML problems wink

bozmandb9

673 posts

187 months

Thursday 22nd December 2011
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Phil. said:
Finally we agree that an LPG conversion has the potential to cause valve problems particularly in the 4.2 S/C where there is a greater risk of it running lean due to the energy levels involved.

To the OP. If you are comfortable with the Engine Management Light (EML) coming on and needing resetting by the installer. If you are comfortable with financial risk of may be having to replace the valves at some point. If you can manage 200 miles betweeen fill ups. If you know how you are going to sell it etc. Then go for it. The point is, it's not a turnkey solution to solve all your economy issues. There are finacial risks involved and there will be at best teething problems with any new LPG installation on a 4.2 S/C.

My experience was over 18 months and 36,000 costing £6k. So I brokeven on the fuel savings but wouldn't do it again due to the problems incurred.

Here's an alternative for you to consider. Buy a TDV8 and have it re-mapped by a reputable organisation like JE and you'll average 25mpg with near S/C performance and plenty of miles between fill ups at any garage you happen to pass. Oh and no EML problems wink
Phil, I totally agree, I'm sure anybody would, that any engine modification done incorrectly can lead to problems, particularly the engine remap which you are recommending. Again, the fact that somebody cocked up your LPG installation, does not make all installations bad, even on this engine. Please tell me what the teething problems were with my latest installation, since I didn't notice any? Possibly due to the fact that the installers have done it before, are using a good kit and are very competent.

As for your guarantee of no EML issues with the TDV8, I take it you've got a miracle solution for the known EGR issues, MAF issues, rough idle etc? Also you won't get 25 with with near S/C performance, that would be an either or. If I want plenty of miles between fill ups I can get up to 600, how many on a TDV8? OK, I'll be using petrol as well as LPG, so it'll be pricey, maybe £180 to fill both tanks against what, £135 to brim a diesel? But then the TDV8 is £5k more expensive to buy, probably more for equivalent spec. The 200 miles I'm getting from a tank are on very fast motorway and cross country use, with no nursing whatsoever. I'm sure I could see 250 plus if I nursed it, but that's not why I got an S/C, or got it converted.

I'm not knocking the TDV8, just saying it's not perfect, just as the S/C is not as problematic as you make out, you just had a bad experience, and I'm amazed you're still recommending the installer concerned after it! From what I've heard most problems on their LPG installations are of their own making.

Obviously if the OP could consider a 4.4 TDV8, it would be a very different kettle of fish!

P.S. A modification which causes any engine to run lean (or rich), can cause severe permanent engine damage, and and engine remap is an example of just such messing with fuelling systems. I'm not suggesting Remaps should not be done, just that they are similar to the LPG conversion, in that it's essential that they are done so as to ensure proper fuelling . Many people rant about how dangerous remaps are - doesn't make it true, so long as they're done right!

Edited by bozmandb9 on Thursday 22 December 10:52

Phil.

5,131 posts

257 months

Thursday 22nd December 2011
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Boz, I won't quote you because I strongly suggest you edit out some the potentially damaging and unsubstantiated statements you have made above against a highly reputable organisation before you find yourself in receipt of a lawyers letter. It’s also against the ‘name and shame’ rules of this forum.

Please take your own advice and 'calm down' a bit. Other people are allowed to voice a reasonable opinion which doesn't always have to agree with yours wink

bozmandb9

673 posts

187 months

Thursday 22nd December 2011
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Phil. said:
Boz, I won't quote you because I strongly suggest you edit out some the potentially damaging and unsubstantiated statements you have made above against a highly reputable organisation before you find yourself in receipt of a lawyers letter. It’s also against the ‘name and shame’ rules of this forum.

Please take your own advice and 'calm down' a bit. people are allowed to voice a reasonable opinion which doesn't always have to agree with yours wink
Name and shame 'somebody'????

I'm perfectly calm thanks Phil, just calmly and rationally pointing out the flaws in your argument, one minute you're bewailing your terrible experience with an engine modification which went badly wrong, apparently from your description due to poor implementation, then you're encouraging somebody to take an engine modification from the same provider.

Just to be clear, if I don't mention a name, how can it be naming and shaming? As for a lawyer letter you're really letting your imagination run away with you! The one bit of your reply which was spot on, I've highlighted!

Phil.

5,131 posts

257 months

Thursday 22nd December 2011
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I despair, you win. Happy Christmas Boz.