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I am setting up a 18 ft flat V Drive and wanted some input on prop selection running a healthy 454 around 600 HP want top end RPM around 6500 RPM and good out of the hole response 2 blade 3 blade size and pitch ??? I know this is not much info but this was a used boat and I don't have a lot of specs
Hey it,s nice to see another v drive owner.
So the first thing about your prop setup is what kind of hull do you have? What gears do you have in the V drive? This is a start.
2 blade props are good for out of the hole due to the slipping in the water to gain rpm so the engine can be in it's power range when the prop hooks up. Also known as "Burning the prop".
3 blade props are much smoother and are hooked up just about all the time. Depending on your prop RPM you can run a brass 3 blad alot cheeper than a steel prop.
If you have 18% over drive gears which are common, at 6500 engine rpm you will have 7670 prop rpm so with a 11X14 your top speed would be + - 101 mph.
Thank you for your reply to my post. I am in the process of getting the info together re gear ratio I managed to aquire a used 2 blade prop which is suppose to be a 11X14 however the markings are not good so I am having the local boat performance shop to check it out. I also aquired a new rudder and packing seal along with some other misc parts including Basset OT exaust. In exploring my new aquisition I discovered that the previous owner put a Wieand square port tunnel ram on oval port heads I plan on running it with 2 660 center squirters. Is there any issues or will this be a liveable situation??
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Originally Posted by Speed trap
The ratio on a Casale split case is staped on the bottom edge of the case nex to the boat hull. This number would be the gears when built. They might have been changed but not likely. As far as a Rectangle port manifold on oval heads, Who ever did that should have there cresent wrench taken away. Don't expect any performance out of that set up. The turbulance is going to be so bad the engine wont like that at all. You just gave up any top end. Change the heads. You will have the best of both worlds. 990s aren't hard to find or aluminum on ebay new are cheap too.
Good luck