Another outdrive ratio question.

[DaveG55]

My boat; '94 21' BR, 5.0l (200HP), A1/G2, 19p SS prop @ about 4600RPM with a top speed of 48-52MPH depending on load and water condition. I got water in the drive and ruined the gears. Having to replace it. Don't have the cash for a new SEI so the mechanic went shopping for a used drive. What they have found is a late model 1.81 drive from a similalarly sized boat. I assume it's a 4.3l V6 which was an option for my hull. Mine is a 1.62 and the way I'm reading the previous thread is I should be ok with the 1.81 drive as long as I reprop to keep the RPM between 4400-4800. This is the information my mechanic is giving me and claims that a tech at SEI confirmed that to him as well.
To me it seems the same as the OP in the prior post with his original outdrive but a step up on the engine. Also, I have a good friend that just repowered to a 5.7 from the 5.o w/o changing his outdrive. He is quite happy with his results.

I guess my question is, will the 1.81 be ok as long as I reprop?

 

[flipbro]

I would not recommend that ratio ( 1:81) On a v8 power that drive was coupled to 4 banger . You need to find the proper ratio (1:61) Or 1:50 to keep performance. But iam sure some one else may have a a little more experience and jump in Good luck!

 

[achris]

As long as you can find a prop of the right pitch to run on that drive, no problem running ANY ratio you like. If you were running a 19" on the 1.62 and move to a 1.81, then look at a prop around the 21" range... Good luck with it... The slower running prop will be much more efficient...

Flipbro. The 4 cylinder (GM) engines ran 1.98:1, not 1.84... V6s ran 1.62, 1.65, 1.84 and 1.82... These were 'standard' factory supplied ratios... If the application needed a different ratio, no problems, just bolt it on....

Chris....

 

[DaveG55]

Yeah, a 21 pitch is where I thought I would start. The mechanic is including a new prop with the outdrive.