5.7 Hemi & LPG
Discussion
Can't comment on the 5.7 but I have a 6.1 hemi in my 2009 challenger and have a prinz system and had no problems as yet, been on a year and 20k miles or so, I had it fitted by Hants auto fuels who checked it out and no reports of any problems, however I will warn you there is someone on hear that will tell you different, when I said mine was LPG he came on and said well your car won't be worth buying as it will screw the engine up bla bla bla he has seen loads of these engines ruined by LPG ect ect make of it what you will but the guy who did mine had done lots of 6.1 hemis in the uk and had never had one cause any problems, I think the guys king the comments may have been from the USA, all I can say is I love mine and would do it again no problem, it makes my car usable as a daily which is what I wanted, I have comments well if you can afford one of them you can afford the fuel it's stupid having a 6-1 if you can't afford to run it, my view is £150 a week in petrol hurts no matter how rich you are and if you can halve your fuel bill and still have the performance when you want it it's a no brainer ! I get to enjoy my car every day :-)
I have a 5.7 hemi grand Cherokee running on LPG.... It's on 90k and the LPG was fitted at 60k by the previous owner....
Mine runs great, except when I floor it... Then it switches to petrol... I've been to see my LPG guy, and he says its a simple case of not enough gas, so he's going to up the feed pipe size from 6mm to 8mm, fit a second vaporiser, and re configure the ECU to suit.... I'm looking at around £350 to get it sorted, but I bought it cheap knowing it had this issue....
Day to day running is fine, it's just booting it that it has the issue...
I also have a 4.7 WJ that's on 135k and was LPG'd at 50k...... That's been perfect, and is still going strong...(wife uses it)
Mine runs great, except when I floor it... Then it switches to petrol... I've been to see my LPG guy, and he says its a simple case of not enough gas, so he's going to up the feed pipe size from 6mm to 8mm, fit a second vaporiser, and re configure the ECU to suit.... I'm looking at around £350 to get it sorted, but I bought it cheap knowing it had this issue....
Day to day running is fine, it's just booting it that it has the issue...
I also have a 4.7 WJ that's on 135k and was LPG'd at 50k...... That's been perfect, and is still going strong...(wife uses it)
It shouldn't do if done properly, also the correct injectors must be used, mine is 425bhp and it still pulls all the way through on LPG, it's just not as aggressive a power delivery as when on petrol :-) prinz is one of the best systems out there and the guy who did mine spends time driving the car to set it up with the laptop so it's running as sweet a sit can.
I had a Dakota with the 4.7 which did around 80k while I owned it all on LPG with no issues, then I had a Roush supercharged F150 also on LPG although that was programmed to switch to petrol un der hard use as although it had the largest injectors & large filters & pipes it couldn't meet the engines demands under WOT. I have friends that have done many miles with LPG powered Hemis, as long as you have a good system you shouldn't have any problem.
swerni said:
Is the tank in the boot or slung under the car?
I'm going to pick up a 6.1 jeep in the new year and an option is to LPG it, glad to read it's not the nightmare some day with the hemi
Just been and filled mine up... Done 173 miles (just running around locally) took 48.85 litres @ 0.699...so £34.15... I'm going to pick up a 6.1 jeep in the new year and an option is to LPG it, glad to read it's not the nightmare some day with the hemi
I can live with that
swerni said:
Is the tank in the boot or slung under the car?
I'm going to pick up a 6.1 jeep in the new year and an option is to LPG it, glad to read it's not the nightmare some day with the hemi
Mine is a tank in the boot behind the seats, I have then made a new panel using the existing boot liner so it comes up covering the tank, so the boot is half the size but still sufficient for what I wanted, if you do end up doing the jeep the guy who did mine has one several SRT 8 Jeeps and he uses Prinz, he also cuts the exhausts on the jeeps and welds in modification to allow the tank under the car, so well worth having a chat with him s he really knows his stuff, I was put onto him from James at North Hants Tyres as he has LPG on his Chevy truck with twin tanks und r the back, the guy is Steve and the company hants auto fuels, if you decide to d it give me a shout and I will give you his number, he is based in Fareham Portsmouth.I'm going to pick up a 6.1 jeep in the new year and an option is to LPG it, glad to read it's not the nightmare some day with the hemi
lemmingjames said:
AdeTuono said:
I'd echo the previous comments. Although not Hemis, I've LPG'ed a 4.6 Ford and now have a Prins system on my 6.2 Raptor, with no issues over many thousands of miles.
What sort of mpg do you now get?vaughan watkins said:
however I will warn you there is someone on hear that will tell you different, when I said mine was LPG he came on and said well your car won't be worth buying as it will screw the engine up bla bla bla he has seen loads of these engines ruined by LPG ect ect make of it what you will but the guy who did mine had done lots of 6.1 hemis in the uk and had never had one cause any problems, I think the guys king the comments may have been from the USA, all I can say is I love mine and would do it again no problem,
I suspect you may be bad-mouthing me here, Vaughn - you are either forgetful or plain stupid, because that is not what I said regarding LPG conversion of a Mopar 372 engine.I'll remind you - I said, "There may be trouble ahead" and when you responded I explained why. This engine (NOT the 5.7 - or 4.9 versions) is very dependent on uniform upper cylinder lubrication that is not typically present in LPG. UCL starvation can cause the valve seats to overheat and in extreme cases disintegrate. The pistons can also be damaged too.
What I did not say was that I'd seen loads of 372's ruined by LPG. All I said was that I thought the conversion risky and therefore unadvisable on this particular motor, which has substantially different internal components to the 5.7. I also stated that to those who are familiar with this phenomenon would probably steer clear of an LPG converted 6.1 hemi.
UCL is nothing like as critical on the 5.7 engine - fewer forged parts, lower compression, smaller ignition explosions, lower burn energy.
Out of interest, just how many 372 hemi conversions has 'the guy who did yours' - who's company name you can't even spell correctly, done - you state "lots" - are there actually "lots" of 6.1 engined cars on the road in the UK then?
Matt Harper said:
I suspect you may be bad-mouthing me here, Vaughn - you are either forgetful or plain stupid, because that is not what I said regarding LPG conversion of a Mopar 372 engine.
I'll remind you - I said, "There may be trouble ahead" and when you responded I explained why. This engine (NOT the 5.7 - or 4.9 versions) is very dependent on uniform upper cylinder lubrication that is not typically present in LPG. UCL starvation can cause the valve seats to overheat and in extreme cases disintegrate. The pistons can also be damaged too.
What I did not say was that I'd seen loads of 372's ruined by LPG. All I said was that I thought the conversion risky and therefore unadvisable on this particular motor, which has substantially different internal components to the 5.7. I also stated that to those who are familiar with this phenomenon would probably steer clear of an LPG converted 6.1 hemi.
UCL is nothing like as critical on the 5.7 engine - fewer forged parts, lower compression, smaller ignition explosions, lower burn energy.
Out of interest, just how many 372 hemi conversions has 'the guy who did yours' - who's company name you can't even spell correctly, done - you state "lots" - are there actually "lots" of 6.1 engined cars on the road in the UK then?
There you are Matt, thought you would be along to chip in soon, sorry if you feel I bad mouthed you as that was clearly not my intension but when you stated that my car would be UN-SELLABLE I probably did think you were being some what a tosser on a public forum, making my car un-sellable here in the UK which is a very small market for such a car, so you basically de valued my car in one comment, thus I was not best pleased as you can imagine, as for not being able to spell ? I presume you are referring to Prinz or Prins ? sorry I don't proof read my responses as its done on my phone and funny enough S & Z are next to each other so me and my clumbsy thumbs mussed have typed the wrong letter oops, mind you as you said I am stupid, ps thanks for your update, oh and here is what you actually wrote when I politely asked why was the 6.1 a bad engine for LPG I'll remind you - I said, "There may be trouble ahead" and when you responded I explained why. This engine (NOT the 5.7 - or 4.9 versions) is very dependent on uniform upper cylinder lubrication that is not typically present in LPG. UCL starvation can cause the valve seats to overheat and in extreme cases disintegrate. The pistons can also be damaged too.
What I did not say was that I'd seen loads of 372's ruined by LPG. All I said was that I thought the conversion risky and therefore unadvisable on this particular motor, which has substantially different internal components to the 5.7. I also stated that to those who are familiar with this phenomenon would probably steer clear of an LPG converted 6.1 hemi.
UCL is nothing like as critical on the 5.7 engine - fewer forged parts, lower compression, smaller ignition explosions, lower burn energy.
Out of interest, just how many 372 hemi conversions has 'the guy who did yours' - who's company name you can't even spell correctly, done - you state "lots" - are there actually "lots" of 6.1 engined cars on the road in the UK then?
"The 372ci motor needs very, very consistent upper cylinder lubrication in order to avoid valve seat damage (valves themselves are less susceptible due to sodium cooling). Piston crowns and valve seats are what you are likely to damage. I would imagine your LPG converted SRT-8 is rendered virtually un-sellable to anyone who has any mechanical know-how with this engine (which has very little in common with it's 5.7l sibling). "
Nicely put Matt thank you, oh an the guy that did my car HAS DONE LOTS OF 6.1's !
Not sure if the US LPG is different to that in the UK but he has not had any problems with the cars he has done. Good day sir.
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