How would one go about using a modified production aircraft like an unmodified one?

Question

I'm not an A&P, but if I created a non-certificated engine & installed it into a production (Piper) aircraft (would be my own plane), what would I do next for the FAA to let me fly it both IFR & VFR, any time of day, and non-commercially? What type of airworthiness certificate would I need? I imagine I'd need a supplemental type certificate? How much do approvals, a/w, and type certicates cost?

Answer 1

That's a good question,

All I would say is that you need to get it re-certified as an Experimental aircraft.  If you're allowed to hold the repairman title for it, then you should be able to modify at will.

Best to call the FSDO on that, and like anything you'll probably get 10 different answers