So, a bbc @ 48-4850, spinning a 'AA', in a 21', in the mid 50's would be similar in performance to the tahiti project?
Dan'l
Not at all. It depends on the HP, I was simply using the examples as a comparison because of the question that was asked on the RPM difference.
My small block powered Carrera with an Alpha I gen 2 will SMOKE a BBC jet in a 21'.... You just have to keep in mind that my mouse has eaten a Rat.
Here is some new math.
If he were to run a 25" pitch cupped Mirage with the same 1.62:1 ratio, the expected speed at 4600 RPM would be really close to 60 MPH, if the gear ratio was a 1.50:1, same prop same motor, the expected speed would be closer to 64MPH. It is all dependent on how much horsepower is being generated. If the motor wont pull the prop, the speed will fall off dramatically.
Am I making sense? ultimately I am thinking the prop choices are going to be limited by the lower gear ratio, also the ratio is low enough that the torque increase will be an issue making it more prone to breakage.
Never did I indicate that this boat wont surpass 55 MPH, but I bet I'm pretty close with saying 60.
GT
