I need to know how to compare the power of the two. I tried doing it by looking up specs but I couldn’t figure it out. I’m trying to figure how much power a plane would need to get moving to that which a ship needs. I know it sounds crazy but it’d be awesome if someone could help.
I actually think that I am trying to compare the thrust.
Piston engines are rated by torque and horsepower, as are turboshaft (turboprop and helicopter, as well as stationary) engines.
When comparing performance however, turbine engines will have the ability to maintain more horsepower at altitude (in less dense air) than their naturally aspirated piston counterparts. This is because they compress air before it enters the combustion chamber.
Turbocharged piston engines will be able to maintain similar at-altitude performance as the turbine, because a turbo-supercharged (ts) or turbo-normalized (tn) engine is actually a hybrid design of the two types. A turbine uses exhaust gasses to compress the air in the intake tract. Ts engines can compress intake air to a pressure greater than normal atmospheric (>29.92 mm/Hg) Tn engines just raise the manifold pressure to normal levels (</= 29.92)
Generally speaking, the turbine has the advantage of greater reliability because of its lack of reciprocating parts, the piston or turbo-piston engine has the advantage of greater fuel economy (higher break horsepower/ specific fuel consumption) mainly because the combustion chamber is sealed during the power stroke.
There are also turbo-compound piston engines, which can be even more efficient…..lots of terms, most folks don’t know they existed anymore. See the Lockheed super-G Constellation for an example of a turbo-compound piston engine driven aircraft.
Finally, to help you with your project, at sea level, where a ship would operate, the horsepower rating of a turbine and a piston engine could be directly compared. Note: some engines are rated in kilowatts, which can be converted to horsepower with a simple formula see www.mr2ownersclub.com/converter.htm .
Just another hint to help solve your problem, compare the density of air and water, and calculate how much each vehicle must displace in order to move.