These are straight pure centrifugal turbojets for the RC crowd, so they're very inefficient. If these engines could be coupled to a bigger fanjet in front, thrust would probably tenfold. Or a gearing for turboprops.
These engines probably burn around 6-8gph per engine, which is about 16gph per hour. This is not that far from what a Rolls Royce C250 (that's in the Extra 500, Silver Eagle P210 and Bonanza turboprop conversion) burns at economy cruise, wringing out 450hp...