i was wondering if anybody knows of a fuel efficient .40-.61 nitro engine in the 2 stroke range or equivelent sized 4 stroke that gets good fuel economy. i know my enya .45 flew for 26 minutes and still had more than half a tank of nitro left. i just want to enjoy long flights but i cant seem to find a us distrubutor of enya engines.

You can order Enya's direct from the factory.

http://enya-engine.com/index_E.htm

I don't see a lot of Enya engines but so far I have never seen an engine get the milage the OS .55 AX is getting.

Unless you go with gas ...

Bedford

Put in a 700cc tank and you'll go 90 minutes.     

The OS S-52 and TT F-54 four-strokes are sippers. 

FWIW, I've noticed running an FAI mix in an engine that will tolerate it (i.e. not very low compression engines) tends to run a bit longer than the higher nitro mixes because you usually lean the needle a few clicks on the FAI mix. Most larger engines will tolerate FAI fuel OK. I've got a little ST G.34 that is a screamer with a no-nitro 75(meth)/25(oil) FAI mix.