The size of the engine has not a single bearing on what it can be used on. I've seen video of a Ford Escort being driven by a Subaru Robin engine, possibly 10hp?
The usable power output is a better factor to determine viable use... Otherwise, the reactors in Nuclear subs would simply be "too small".
__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"