Had a look on google and found quite abit ie 1/4 scale Merlin dynamotive.netfirms.com/merlin.They are also working on 1/5 scale Allison & Gryphon.Also some other sites.Not cheap,but not too bad,you would pay more for the average model steam loco,Sorry didn’t look for drawings.Quite interested,served a apprenticeship on Continental aircraft engines back in the 60s,and one of the chaps I worked with is the engineer at the NZ Fighter Museum,and he works on the real thing along with Allisons for the P 40s,they have a Hurricane Mustang and I think they have 2 Spitfires,plus other aircraft from time to time.Ian S C