136 to150 gear change
 

I have a bravo 0ne with 136 gears in it with very low hours I used it on a twin engine cat Now I am going to use it on a single engine cat so I need to change the gears to 150 The lower gear case is noseconed with low water pickup which I welded on . Is the gear change done in the upper only (which I think) or should I try to locate a complete upper with HP 150 gears or should I buy HP gears and use my upper case The drive is a very low hour unit and is a 465 hp unit Am I correct in thinking the gear change will be done in the upper.

Ratio changes with the helical teeth uppers ( std bravo ,X)
are one in the upper.

XR's, ( straight teeth) there's only one ratio of uppers made, so the ratio change is done in the lower.

Why not just run the 1.36 first and see how it does???? If its going to be at least a 75-80mph boat, then the 1.36 should be fine. You just have to prop it different.
I have 1.36's on my 32 AT with 24" Bravo props and they are fine. If I had 1.50's I'd probably need 28's.

if u have a choice where the drive can b located? then use 136 and a higher x dimension with a 6 blade.

thanks for input. I forgot to mention that the boat is a 30, cobra cat with 500 bull dog engine MYsecond time around with this boat only when I had it the first time it was twin now a single. the other owner had problems with performance with 136 replaced with 150 and did alot better I bought it back without power and put in a 500 bulldog with bravo 136 so im expecting same performance problems he did because he had the sister engine and drive from when i sold it to him when he changed to 150 boat did low to mid 80s I thougth about going down in pitch also just not sure if it will get me where he was with the boat

bull dog huh....what a freaking cool engine! so rare!

single engine cats r inherently hard on power trains because of the extreme dynamic range of loads....like i said if you can move that drive up i would to take full advantage of todays prop technology.

but really there r so many factors and even a pic of the transom would be a ton more helpful to even try and come close to a recommendation.

u have the numbers from the last guy?...speed, rpm, gears, props, x dim?

cheers mate

I do know that he ended up selling the bravo 136 and buying the drive thats on the boat in this picture with150 gears he than built a blower motor for the boat I bought the boat back less engine/drive

u have one looking from the back?

is this the exact drive setup you are using?

no when i sold him the boat he got one engine /drive setup with the boat I kept the other He did the transom work to change it to single(VERY NICE JOB TOO) He had rpm problems with the136 drive so he sold it to get the 150 drive that is on the boat in the picture. I bought the boat back and put the other engine/drive back into the boat but didnt get it back together until recently so I am going to winterize now so I didnt get to try it with 136 but know he had tried props to get rpms up so he went to 150 drive