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-   -   Mph lost goin to b max drive from xr drive (https://www.offshoreonly.com/forums/general-boating-discussion/324740-mph-lost-goin-b-max-drive-xr-drive.html)

slippy0217 04-03-2015 10:53 AM

Mph lost goin to b max drive from xr drive
 
Right now I have xr drives with 2 inch imco shorties and my 42 fountain is running mid to low 90s. I'm swapping over to b max uppers with imco 2 inch shorties. How much mph if any will I loose swapping to bmax

indysupra 04-03-2015 10:57 AM

I would think none. It's the same gear set.

slippy0217 04-03-2015 11:23 AM

Xr 1.5 bmax 1.36 but goin to smaller props due to gear ratio change

bor 04-03-2015 12:51 PM


Originally Posted by indysupra (Post 4287509)
I would think none. It's the same gear set.

upper gear is much bigger 5" if I m correct so the b max will eat more hp then the xr and the ratio change could also hurth a little bit .but its much better not to worry to blow a drive !

jmoore1225 04-03-2015 03:06 PM

2-4mph from what I hear....

glassdave 04-03-2015 03:15 PM


Originally Posted by slippy0217 (Post 4287513)
Xr 1.5 bmax 1.36 but goin to smaller props due to gear ratio change

it may just be a lateral move. Going to the smaller prop on a taller ratio is going to benefit from having a more efficient prop in the water. What you lose in parasitic loss you may gain back in less prop slip. (I have nothing to back any of this up . . . . just trying to be an optimistic fellow boater lol)

abones 04-03-2015 03:45 PM


Originally Posted by glassdave (Post 4287587)
it may just be a lateral move. Going to the smaller prop on a taller ratio is going to benefit from having a more efficient prop in the water. What you lose in parasitic loss you may gain back in less prop slip. (I have nothing to back any of this up . . . . just trying to be an optimistic fellow boater lol)

I agree with that theory, Slippy what pitch prop were you running with the 1.50 ratio?

jmoore1225 04-03-2015 03:54 PM

slippy what year Fountain?

Griff 04-03-2015 06:40 PM

Going from a 1.5 to a 1.36 normally requires about 3" less pitch. I would go down 4" switching to the BMax.

offshorexcursion 04-03-2015 06:43 PM

Really doesn't matter the strength increase is worth the money!


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