transmissions for cummins 250

[spencer]

Searched the site.
It seems most of the application have 1.5/1 trannies with these motors , is it okay to have 2/1 or what negative effects would that yield.

The motors that I am looking at have twindisc 2/1 mounted to them.

Thanks

[In Memory of Vicroy]

Well, the net result is the prop will turn slower with the 2:1 than the 1.5 (obvious) meaning you will need more diameter on the prop and/or more pitch to accomplish the same as the 1.5. I have 1.5s with the same motors in my B31 FBC and turn 21 x 22 three blades. 21 inch diamter props are about as big as you can go without major work. So you will need to up the pitch, which will get you "out of square".

Whatever you do, in the end these motors need to reach 2650 rpm WOT with a full load aborad, and can be cruised at 2400 if they make the 2650 WOT. Great motors for the B31. You might check with some of the marine gear shops that advertise in Boats & Harbors and see what kind of deal they would make to swap out the 2s for 1.5s.

UV

[wmachovina]

I bought a pair of 250 cummins with 2:1 gears out of a burned trawler. Finally I found some 1.5:1 gears and swapped them out. It's the way to go. You could maybe make the 2:1s work but the prop size would be a challenge. Just find some 1.5s, it can be done.but then what do I know. My boat runs real nice w 250s and 1.5s

[spencer]

Thanks all for the responses
This info will help with the final offer
Mechanic and I are going to listen to them tomorrow

Spencer