85scorpion

I am in the process of re-doing my Chris Craft Scorpion 210. I've replaced pretty much everything on the boat and the last 2 things left are the motor and lower end. I have a new motor that will be going in once I'm done with the engine compartment but I am just now starting to look at lower ends. I see different ratios to the alpha 1. What are the differences, do certain ratios give me a higher top end better hole shot etc? And how would I calculate the lower end that I have now?

Randy Nielsen

iTrader: (4)

I believe v8s have a 1.47:1 ratio v6 or straight 6 1.65:1 or so & 4 cyl 1.8 something:1. Gear changes are done in the upper half. Randy

85scorpion

Perfect, thank you!

powerplay260

I believe alot of the V8's run 1:50 as well

boats74

V8 Alphas were 1.50s, then they changed to 1.47s. My 210 Scorpion has a 1.50, soon to be replaced with a 1.47

tbanzer

They had a 1.32 behind a 454 for two years I believe.

A.O. Razor

Yup. I believe the SS also ran the 1.32s. It was mostly due to the fact that the boats running 65+ needed prop selections since the motors topped out at 4600. The SBCs usually ran the 1.62 and the V6s ran 1.62 or 1.81 depending on hp. 4I motors ran and run the 2.0 or 2.4. You could also special order them as either high altitude geared or high speed geared. That's basically just running a 1.81 instead of a 1.62 or a 1.47 instead of a 1.62 ect.

Choose the ratio that gives you the best prop selection. That is way more important than the ratio itself. If your boat/motor/drive package ran 45 @ 5100 with a 1.47, many props would be too high. Unless you plan to go above 70-75, gear it so you can use 23-25 inch props. Everything from LaserIIs up to Maxies and Hydros ect. is more or less available in that size.