A multirotor vehicle capable of operating in air and underwater developed at Rutgers has opened the door for combined aerial and underwater operations. The current vehicle is unable to carry out payload based missions due to low thrust outputs. This study examines the effects of scaling motors and propellers to larger sizes in air and underwater. Motor tests were conducted on two of the largest commercially available motors measuring rotational speed, current input, and torque load. These two motors were then compared with each other and smaller scale motors with regards to the torque load, power output, and efficiency. Afterward, three varying size motor-propeller combinations were examined in air and underwater. For each of these tests, the rotational speed, current input, torque output and thrust output were measured. Torque and thrust were observed to hold a linear relation with each other regardless if the system was in air or underwater. Performance for motor-propeller combinations were observed to increase along with size in air, but was more varied underwater.