Safety and Benefits of Propane Powered Small Engines over Gasoline

Reader Contribution by Derek Sherwood

So why would anyone want to convert a perfectly good gasoline engine to propane? There are a few good reasons, which we’ll go into here. First, though, I want to put out the standard safety and disclaimer information that anyone who wants to start this conversion should know.

Propane is a flammable gas under pressure. Observe all manufacturer recommended safety precautions as seen on the propane bottle while completing the installation of this kit. Check for leaks before operating the mower using a soapy water solution. If you are operating the mower and smell propane, immediately shut off the engine and leave the area. Propane is heavier than air and will pool in low areas, which can cause flash fires or explosions. Work on this conversion outside and do not store the mower inside with a propane bottle attached.

Converting a lawnmower or other small engine fuel system may be illegal in your area, especially in parts of California. As the effectiveness of the conversion process relies solely on the skills of the installer, no guarantees are expressed or implied as to whether or not your results will be the same as the results shown in these plans. Furthermore, as material quality varies greatly between manufacturers, there are no guarantees that the conversion process will be the same or similar because of the materials sourced and the methods of installation. All gasoline to propane conversions are undertaken at the user’s own risk.

Benefits of Propane as a Small Engine Fuel:

Propane as a small engine fuel provides a variety of advantages over gasoline. The environmental advantages alone make a propane conversion worthwhile; however it is important to note the other benefits of a propane-powered lawnmower.

1. Storability — Propane does not go bad and can be stored indefinitely. Modern gasoline, on the other hand, has a shelf life of only a month or two without stability additives, and even then cannot often be stored longer than six months before degrading.

2. Cleanliness — Propane is not spilled like gasoline when refueling. It is estimated that Americans spill 17 million gallons of gasoline each year refueling small engines. This represents an environmental hazard as well as a safety hazard, since hot engine parts can cause spilled gasoline to catch fire.

3. Reduced Emissions — Propane burns much more efficiently (around 90-95% efficient) than gasoline and produces less carbon monoxide and other greenhouse gases. Propane does not evaporate like gasoline, so the evaporative emissions are reduced as well.

4. Extended Engine Life — Propane has less BTUs of energy per unit than gasoline. While this means that it takes more propane than gasoline to power an engine, the advantages are that less energy is wasted in combustion of propane. Engines run on propane run cooler, which means less stress on internal engine parts and extended engine life.

5. Extended Service Intervals — Propane does not gum up over time like gasoline, because it is a gaseous and not a liquid fuel, so carburetor problems are not an issue. Propane combustion does not produce excess carbon and gunk like gasoline, and so propane engines typically have a longer interval between oil changes.

6. Portability — Propane in the disposable cylinders is easier to transport than gasoline.

In my next post, we will talk about what you need to do to begin the conversion, and how it all works.

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