grant-RCU

I am still a bit new to gas engines myself in that I am on my second gas engine project, so I can really appreciate your question. Keep this in mind when considering my opinion, but I will add some things I have learned, which you may find helpful.

I agree with Kris^ in first wanting to consider what airplane you are going to be mounting in. You will also want to consider the options of going with electronic ignition vs. an engine with a magneto generated spark. Electronic ignition provides a hotter spark and in many cases makes engine starting easier. Conversely, an engine with a fly-wheel usually runs a bit smoother than one with electronic ignition. You will also find that weight varies a good bit from engine to engine. Make sure you consider total weight when doing a comparison. Include things like the muffler, electronic ignition (if applicable), battery packs required, etc. Don't pay much attention to HP ratings. These are usually very misleading. I have often heard it said, there is no substitute for cubic inches.

BackAfter30 mentioned performance, customer service and reliability. These are very important when making your selection decision. The gas engine market has really seen it's popularity grow in the past few years. There are now several quality name brands out there. You can just about pick any of them, based on the criteria mentioned and not go wrong. DA is known for their customer service, which being new to gas will be important to you when you have questions.

I also agree with Geistware in that a single prop bolt does make mounting easier. You need a drill press and a prop jig to drill a multi-holed prop. Even with these you have to work the holes a bit to avoid any binding, and it just takes more time. IMHO the only real benefit I see to a multi holed prop is that it looks cool :-) Maybe there is a safety issue with multi bolts, which makes sense, but my single bolt prop never came loose. I have had both and found the single bolt is much easier.

In summary, the criteria I would use would include the following. Size of the engine (cubic inches)required for the airplane being considered. Go to the high end of the scale vs the lower end. Carb location and cowling room for mounting. Total weight, Ease of starting, reliability, customer service, history from other users - RCU has a wealth of info on just about any engine. Cost, and in the end what you feel you want.

Don't be afraid of electronic ignition. I was at first and went with a mag. generated spark. I have electronic ignition on my second engine and it is easier to start. Good luck and I hope this helps you.