Rutan.
"Is it possible it's perceived high failure rate is simply because there are a lot of them around. A lot of Holdens crash but there a lot of Holdens.
Internal combustion engines have been around for well over 100 years. It shouldn't be too difficult too pinpoint Jabs problem area if indeed there is one".
I see where you are coming from Rutan, but in my experience, the failure rate
Is definitely not perceived.
And yes, light aircraft Engines (lycoming,continental) have been around a long time, time enough to put all of the lessons learned in to their Engines, long ago.
Why reinvent the wheel. I'm not saying you should not attempt to build your own engine to suit your own needs, but surely you would build on lessons past.
I remember when Rotax engines became more common, I didn't think too much of them at the time, but they have proven themselves to be an extremely reliable, well Engineered little engine.