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Author Topic: LPG in car, injected as liquid or gas?  (Read 5324 times)


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LPG in car, injected as liquid or gas?
« on: May 25, 2022, 03:26:16 PM »
My car has a lpg installation in it. It consumes the same amount of lpg as it does on gasoline (1 liter, 5 km). Having read several stories on the vapor carb, pogue etc. I come to the conclusion that the lpg being used in the engine must be also liquid-state. The energy difference between lpg and gasoline is not that high.
It seems that, through the use of engine coolant, the temperature of the lpg is raised through the so called "evaporator", but I have a hard time believing it leaves this evaporator in a gaseous form.

If there is anybody who can shed light on this, please let me know. It seems to me, that for instance in countries were cooking on propane (big portion of lpg), evaporators are used on gasbottles and they seem to 100% convert the liquid into gas. Were we to use something like that in a car, the car could run on vapors only and have a lot higher mileage!?

besides that, if the lpg in car were also used to cool the interior as an "aircon", since propane cooks around -38 degrees celsius, with a kind of heat-exchange/evaporator, it would function as a double energy source and you could omit the compressor.

hope to get more insights on this topic.


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Re: LPG in car, injected as liquid or gas?
« Reply #1 on: May 29, 2022, 04:59:01 PM »
This might help you understand the process:

Hope that helps,
Edward Mitchell
CEO and Owner
True Green Solutions


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Re: LPG in car, injected as liquid or gas?
« Reply #2 on: May 30, 2022, 03:17:33 AM »
Thx for the link! I read it, and did some more digging: BTU gasoline 138.500, LPG 91.500. That is roughly 2/3 of the gasoline.

If the pogue carbs could run so efficient on gasoline vapor (unfortunately no reliable numbers) and the stories of "old" whereby vapor conversions won the organised efficiency "races", it still does not make sense that lpg cannot achieve a better mileage.

The link that was given, tells about the working of LPG and claims some designs use real vapor. If that is true, than maybe the cold temperature of the vapor is "problem".

My thinking is that lpg is not contaminated with all the gasoline additives and therefore some alterations to the system might improve mileage. Realizing the danger of such actions, it should be done in a careful safe manner. Thinking "builder-style"; if a regulator can be modified, a small camping gas container with an evaporator could run a small motorcycle as a test. Anyone know who did this?


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Re: LPG in car, injected as liquid or gas?
« Reply #3 on: May 30, 2022, 03:36:21 PM »
Liquefied petroleum gas LPG:

obtained from natural gas and oil production but is also produced increasingly from renewable sources.
Its unique properties make it a versatile energy source which
can be used in more than 1,000 different applications.
In its liquid form, LPG looks like water.
Yet, because of its unique properties,
one litre of liquid LPG, expands to 270 litres of gaseous energy
allowing a lot of energy to be transported in a compact container. 

LPG stands for “Liquefied Petroleum Gas” and the term is used to describe
two Natural Gas Liquids: propane and butane, or a mix of the two.
Propane and butane are chemically quite similar but the small differences in their properties mean that
they are particularly suited to specific uses.
Often, propane and butane will be mixed to get the best energy yields and properties.

Propane’s lower boiling point is perfect for outdoor storage and it is primarily used for central heating,
commercial applications, cooking and transport.

is mainly shipped in cylinders for portable applications such as mobile heaters or for
leisure activities such as boats, caravans and barbecues.
Butane can also be used as a propellant, refrigerant or to fuel welding torches.

Advantages and disadvantages of LPG

The advantages of LPG are
It is non-toxic, non- corrosive in nature.It burns cleanly and has high octane rating i.g. more than 100 RON (Research Octane Number).
LPG engines have less knocking/ vibration.
It does not produce harmful emission like CO, NOx and higher hydrocarbons.
Particulate emissions are also less. So frequent cleaning of the combustion chamber is not required.
The  disadvantages of LPG are

 It causes suffocation, in case of leakage as it heavier than air.
It is hazardous as it inflammable gas.
It is consumed more as it has low energy density.
It does not provide power to the vehicle in mountains or rough terrains.
It is costlier than CNG.
It has to be supplied in a heavy steel cylinder.