Selecting the size of a nitro boat engine may seem difficult however it is a lot more simple than for example, electric setups.
The nitro engine size required is dependent on mostly hull length.
The following chart represents the nitro boat engine size required for a set Hull Length.

Length         Cu. in.                    CC’s

20-27″          0.15-0.18 cu. in.     (2.5-3.0cc)
27-32″          0.21 cu.in.              (3.5cc)
32-36″          0.45 cu. in.             (7.5cc)
36-40″          0.67 cu. in.             (11.0cc)
40+”             0.90+ cu. in.           (13.0+cc)

In some cases it may be necessary to select an engine displacement that falls outside of the range provided. However this chart will provide a very good baseline on which engine to select for any hull size.

Higher quality or more expensive engines will generally provide more power. It is advised to shop with caution when looking at engine horsepower values. Horsepower values are an excellent and the best measurement for determining how much power an engine has. This measurement varies over several manufactures and makes it difficult to choose the more powerful engine. In this case it would be best to ask on our Forums whether the engine or another option would better suit your application.

As you may expect, a nitro boat engine increases in power and weight as you increase in displacement. A more powerful nitro boat engine will spin a larger prop increasing potential speed and prop thrust.