Honda G100K2 Applications Manual page 15

FUEL SYSTEM
PROPANE FUELED ENGINES
Propane is a by-product of the petroleum refining process. It is an extremely clean burning and relatively efficient
fuel. Because of this, it can be used in engines operated in well ventilated indoor areas.
But, propane isn't without its disadvantages:
it causes engines to run at higher operating temperatures
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it reduces lubrication to the valve guide area because it is a dry gas, not a liquid
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- it reduces the engines power output: the calorific value of propane is higher than that of gasoline,
Gasoline 42.7 MJ/kg
Propane 46.3 MJ/kg
Butane 45.6 MJ/kg
but the stoichiometric ratio (air / fuel ratio) for propane is higher than for gasoline
(the volumetric efficiency of the engine decreases with propane use because 5% more oxygen is
needed for combustion).
Gasoline 14.7
Propane 15.5
Compared to gasoline, propane produces less carbon as well as reduced carbon monoxide giving cleaner
exhaust gasses.
LPG is Liquefied Petroleum Gas comprised mainly of propane and butane. The main component of LPG is
propane, but the percentage of propane content can vary from day to day production.
Some considerations on propane fueled engines:
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Ventilated indoor use is possible.
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CO and HC emissions are drastically reduced.
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A minimum carbon deposit in the combustion chamber leads to a long term guaranteed power output.
•
Long operation time is possible with large propane tank.
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The engine is approved for propane use by the manufacturer (minimum 95% propane content).
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The specific fuel consumption is low.
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Up to 26% better fuel efficiency compared to a similar gasoline engine.
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The engine power output is about 5% lower.
•
The propane gas octane rating of + 100 gives troublefree engine operation.
•
The propane engines meet the emission regulations
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Only propane fuel to be utilized.
If gasoline (producing considerable more carbon) is utilized in a propane-spec engine, carbon may lodge
between the larger valve seat and valve face reducing compression and causing other problems.
•
Recommended oil for propane engine usage
API service category: SE/SF/CC
SAE viscosity grade: over 0°C single grade SAE30
As valve cooling and lubrication is critical in a propane engine, use of normal engine multi-grade oils may
cause valve sticking, increased oil consumption and reduced oil life.
Under 0°C multi grade SAE 5W30
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