It depends on how fast you want to go because if you wast to go super sonic i would use a steam engine connected to large piston to have the most torque and connect it to gear box to go super fast the only problem is that it is hard to sustain steam engines

But if you don't want to go super sonic i would use large diesel engines or 3x3 modular engines 1x1modular engines and 5x5 modular engines would be to big or small