2.4ghz ...
I met a guy at our last warbirds meet who told me he had a DLE55 (5.5 hp) on his and he said it had so much power he was afraid to fly it at full throttle. He said he was afraid it would it tear it apart. Ihave read about and seen vids of Ulitmates with 50cc sized engines and they all seem to be holding together fine. So, he may have been exagerating a bit.
I'll bet your 56cc is a rocket. Which prop are you running?
RJ