1.36 vs 1.50 bravo
 

i had a 1.50 ratio bravo 1 stolen and found a nice 1.36 ratio bravo 1 drive,question is how much will that change the RPM needed to turn the same prop.
Can I correct by using a diff pitch prop?
Its on a late model 21ft ski boat with a 350 mag 300Hp.
Thanks for any help or suggestions!

You can correct it with a prop. You would need to go down 2" in pitch...that will get you very close. Use this:

http://www.go-fast.com/Prop_Slip_Calculator.htm

only 2?

Ok great thank you.
Looks like a 450 rpm drop so 2-3 degree in prop change.
Thanks!

Thats what the calculator says...Reality may be different. Usually you dont go to a higher ratio until you have ran out of prop pitch in a given line of props.

fixx
 

the only down side will be you may loose acceleration,how fast your boat use to go to a certain mph may be a little longer time to get their..Also you may loose the spap from the engine's power..

For a ski boat and that engine combo, I would not use a 1.36. Its most likely about a 600rpm/3" pitch difference.

I went from a 1.50 to 1.36 and went from a 32p bravo to a 28p bravo. Also I have an almost new bravo 1 upper and two xr lowers that are 1.50 with DWP for sale if interested.

how does your boat run compare to the 150 to the 136 ???

Not as well as mine!:evilb:

I don't think Mike will know & neither will I. We both changed TONS of stuff, including the drive heights & gear ratios when we re-powered.

My boat did everything better when it had 1.36 drive ratio. As long as you can get it propped correctly, I would buy it. Only down side is the 1.36 gearsets are becoming rare.

So are the ratios built into the upper or the lower?

Yours are XR's right ?, if so, it's the lower gearset that determines the ratio. ( there's only 1 style of XR upper gear sets)

I had the power when I switched gears and noticed no difference in performance but like what has been said, you have to prop it right. And Jason last year was my first year with the boat. Did everything in less than 6 months. You may want to keep posting that as much as you can because you may not be able to in a few months.

I have been told that 2004 and up are a little different. Something about adjustment I think. Anyone know if this is true?

Yes XRs and I need a spare!
Trashed one pretty good this time.

There's a different pinion bearing arrangement, and proceedure for shimming the upper gearset on the newer
one's, but that's just for the uppers.

Welcome to the club:eek:

What broke ?

Spare upper or lower?

Whole one would be nice 1.36.

As for what broke MY knowledge is still learning but the prop shaft broke in the back gear, the upper gears are pitted pretty badly and the shifting plate(?) w the knob on top snaped off.
Bout 3K is what I REALLY understand!

That's what broke on mine at the shootout ( propshaft
inside of the gear)

The pitted upper gears are a common thing on these:(

Never had any problem with the shifting mechanisms.

If you're on the same schedule as me, you'll be
breaking a vertical shaft next:rolleyes:

$ 1600 for a upper gearset, $750 for a propshaft,
$ 3k sounds about right

I broke a shaft inside the gear too & I did it at LOTO. Must be something in the water.