Like most that try to make this a viable replacement you aren't being practical. The most used thing that I'm aware of that used a Stirling was back around the 1920 or so, a table fan, and it didn't, couldn't move much air. Stirlings now and back from the time they were invented still suffer from the same problem the sealing of the pistons. When you get a good seal you have too much stiction/friction on them, so they don't move easily.
The Stirling also needs to be bigger than any other engine for it's output size. In todays world that is a deal breaker. Find a way to get the same power as an internal combustion engine in the same size package or smaller and then the Stirling will start to make progress.
"Stirling engines by definition cannot achieve total efficiencies typical for internal combustion engine, the main constraint being thermal efficiency" "However, it has a low power-to-weight ratio,[49] rendering it more suitable for use in static installations where space and weight are not at a premium." both quotes from - https://en.wikipedia.org/wiki/Stirling_engine
