3000W Chinese Gensets Info.

SonicLogic wrote:
Professor, I am curious as to your satisfaction with the generator that you converted for use with propane. Knowledgeable mechanics to which I have spoken say that converting a small air cooled gasoline engine for use with propane is very problematic.

They say that propane has a slower flame spread rate than gasoline so the timing needs to be advanced to compensate. They also say that propane does not provide any induction cooling in the engine or any valve lubrication (as does gasoline) so the cylinder and valves run hotter.

In short, I’ve been told that propane conversions do indeed work, but to do it right you need to put in a better valves, harder valve seats and advance the timing in addition to changing the carburetion.

I have also been told that bi-fuel generators are more expensive mainly because they have the aforementioned added features built-in.

Does this coincide with your experience?

No. I have not experienced any of the so called negatives you mentioned or others such as lower power.

That said, the problems cited may indeed exist. The question is how serious are those concerns, and if they will indeed have a negative impact upon a small air cooled engine used for intermittent power back-up.

Two of my LPG conversions, the 5500W Generac with a 10HP Briggs engine and the 7,500W Champion with a 13HP Chonda engine, have performed for many hours with no apparent failure. The Briggs once ran a full 10 days with no shutdown after Isabel hit our area.

US Carb has completed and supported kits for thousands of LPG conversions on small engines. Do a Google on failures from US Carb kits and see what you find.

Coming from a community of dedicated "scholars", I am very familiar with research that differentiates between the outcomes of changing parameters in engineering designs and tests. I have also learned that many times these results are trumpeted and overstated - often beyond reason. And yes, they are often ignored in the interest of economics. If one were exclusively in the business of building gasoline engines and providing gasoline as a fuel, I would venture to say they would undoubtedly exploit the problems of using LPG. On the other hand, companies that have an interest in LPG fuel systems would tout the obvious benefits of such a conversion.

Somewhere along the line we must sift through all the alleged facts and separate them from fiction and preference.