Prop Questions
 

Hi guys, I am new to your forum but not OSO. I own a 1988 Baja Force 265 that I repowered with an HP500. I Run about 63 on GPS. I just bought a supercharger for it..(250) and I am trying to get an idea of how it will be propped. I have done some calculations and have come up with what I feel is alot of slippage to run 63mph.. I run a labbed Bravo 1 24*. I figure at 5100-5200 rpm my slip must be well over 20%..is that high?...I am guessing I will need to go to a 28* when I am finished installing the 250...I wonder if I need a different type of Prop? 5 blade?..I do not want a 3 blade because I hate the way the handle..btw..it will be a B&M 250 with twin holley 750's..making about 4.6psi boost..looking at 650hp give or take..I did some work on my HP500 3 years ago and it is actually is a 509 now..the cam train is all stock HP500 but I worked the heads a little bit..also I will be removing the Gil exhaust in favor of CMI uni-top. Thanks for any input..sorry for the book

OK,

Your slip is in the 16% range. Three blade props typically run pretty good on your boat style. However, knowing that you like the handling of the 4 blade propelles, trying a REV 4 propeller isn't a bad idea. These props are only available to 25 pitch. Untill we know this won't hold the R's down as needed, I'd keep them in mind.

B

If I calculate 5200 rpm, 1.5 ratio & 24 P Bravo1 @ 62mph..I get .21 slip...am I doing something wrong here? How can I lower my slip..is that even posible? I guess I will need to wait until my blower is installed to see what prop I need but can anyone take their best guess to get me close...the engine guys tell me to expect 4* with this blower..is this right? that would put me at a 28p..

A 24p Bravo 1 probably measures closer to 23".
Labbed props typically slip more than stock props, hence your high slip numbers.
After your mods, test with a stock 26p and stock 28p B1.
Then have BBlades dial it in for you...

Right on..thanks.makes sense!