Prop Choice?

[Lumpy]

Hello,
The current prop on my flattie is a 3 blade 15 pitch. I don't really ski and would prefer more top end if possible. I am not sure what the overdrive ratio is in my hallcraft. How much more top speed do you think I would gain if I were to go with a 2 blade prop? And will it turn higher RPM? What pitch do you reccommend on a 2 blade?Right now my rpm tops out at about 4700. Top speed as of right now....I really have no idea. I used to have a jet that did 64 on GPS and this thing feels way faster so my guess is mid 70's. I would love to see 90 someday. I have a 427 that runs great with low hours. I just bought this thing from a 72 year old man who was the original owner. The boat is a 69. What do I need to do to see 90? Gears, prop, etc.? Do I need a totally pumped big block? Thanks!................Lumpy

[V-Drive Tom]

LUMPY, Yes you will gain top end speed with a 2-blade,also 2or300 hundred RPM. You should look for an 11-1/2x15. Don't go smaller than 11-1/4 Diameter. If you make a deal on a cheap prop, you should send it in to have it checked for cracks,re-shaped and balanced. cost $120.00. Then you know you have a safe propeller. Cost of a new prop is 650.00 to 750.00. You will need 6700+ RPM with a 1.15 gear ratio and a 2-blade to get close to your 90-MPH goal. http://free.***boat.net/ubb/smile.gif TOM..

[Lumpy]

Thanks for the reply Tom,
How do I know what my gear ratio is? I have a velvet drive tranny model 72c which is 1:1. Would changing gears in the v-drive itself help for more top end also? Thanks again.........Lumpy

[V-Drive Tom]

LUMPY, Need to know what RPM your reaching now and exactly what prop your running now to know if you can pull more gear. If you put in more gear than your power can handle, the boat will become lazy off the line. You want to reach your engines RPM capability as quickly as possible,if you want a boat thats going to be impressive in a lake race. PS. You need to DITCH the velvetdrive if you realy want to get ALL you can out of it. But thats just MY opinion!

[Lumpy]

V-driveTom,
The prop is a 12x15 3 blade and max rpm is 4700 rpm. Thanks......Lumpy