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Blutarsky 12-16-2010 04:44 AM

LPG modding & Valves Tearing?
Hi there guys, I'm running my HEMI 5.7 on LPG and little worried about the valve tearing risk.

Here in Italy there’s a kind of never-ending debate about using LPG as a propellant in HEMI 5.7 engines.

As you may know, LPG is being described as a non-liquid propellant, that apparently has only a unique drawback: valve lubrication.

That is, some engines may suffer from using LPG as a unique propellant, narrowing down valves and seats lifetime; some cases are reported here in Europe about some engines using LPG, tearing down valves after only 30.000 Km. Other engines are being reported to be fully functional after 400.000Km running uniquely on LPG.

Critical factors about using LPG as a propellant, seem to be:
- Global engine mileage
- Engine RPM, where high RPMs engines seem to suffer more
- Engine power, where weaker engines will suffer more
- Valves and seats alloy; tougher or weaker alloys may be crucial, due to exposure to higher temperatures

Having said so, we where wishing to hear from you about this particular propellant usage.

Great if someone could witness it's experience after a long-mid term usage on LPG...

StoneCold 12-16-2010 06:53 AM

Re: LPG modding & Valves Tearing?
First I've heard of this. There are a number of high mileage Jeeps (usually XJ's and WJ's) over here that have been converted. I also know of a couple of Subaru Imprezas that have been done and none have had any issues.

I ran a converted XJ 4.0 about 6 years ago with no problems whatsoever. That said it could well be different story with the Hemi, but that said if the boxster engine in the Subaru copes fine (and it's quite a high RPM engine) I would imagine the Hemi would too.

The only drawback I've experienced is that it isn't as cheap to run a vehicle on LPG as it's made out. You can use upto 25% more LPG than petrol, even though it's around half the price at the pump, it takes at least two to three years to recoup your investment

Blutarsky 12-20-2010 04:20 PM

Re: LPG modding & Valves Tearing?
There are many people converting this engine out there, however it is unknown what valve tear/recession risk is running on it...

NeilF 12-20-2010 05:08 PM

Re: LPG modding & Valves Tearing?

I've not had any real direct experience of lpg on the Hemi, but it maybe worth looking into things like Flash Lube if you are worried about potential negative wear effects of running lpg.



rvtifer 12-20-2010 05:58 PM

Re: LPG modding & Valves Tearing?
There is indeed a risk of shortening the life of the valves using LPG. This is one of the reasons why the injection system always start the car on gasoline and no longer offer the option of a full time LPG like the older systems do. On some systems you also have the possibility to run on 95 % LPG and 5 % gasoline if that is a concern.

I am 34,000 on a 2006 WK HEMI (here) and have not experience a problem but I do go on gasoline once in a while.

What system are you running ?

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