outdrive change question

[pondscum69]

I have a inline 6 150 hp mercrusier. I took the outdrive from a 233hp V8 and put it on mine. I knew the gearing would be different. But it just bogs down way too much. Im also running a 21 pitch prop. Can I make up for the higher gearing by dropping my prop down to like a 14 pitch?

 

[Bondo]

Re: outdrive change question

I have a inline 6 150 hp mercrusier. I took the outdrive from a 233hp V8 and put it on mine. I knew the gearing would be different. But it just bogs down way too much. Im also running a 21 pitch prop. Can I make up for the higher gearing by dropping my prop down to like a 14 pitch?

Nope,... Welcome Aboard,... The drive ya need is a 1.65:1, or possibly the 1.84:1...

The drive you put on is 1.32:1, or possibly a 1.5:1....

They don't make a prop small enough to make it work...

 

[jestor68]

Re: outdrive change question

If a V-8 can turn that ratio, a 6 cylinder can turn it; just with much less pitch.

Your idea of dropping down several inches of pitch will work. Compared to the 21"; dropping to a 15" would raise your WOT rpm by about 900-1200 rpm. Since the difference in prop speed between a 1.81 and a 1.47 gear ratio is just 575 rpm, that reduction in pitch should take care of it.

Since they make props all the way down to 11" of pitch for your drive, there is no reason you can't find one that works.

If you visit the Mercury prop selector and put in your data; then change the gear ratio to the next step, you will note that it changes the prop pitch by one step(2") for each step in gear ratio change.

I would suggest a Solas 15 X 15 as a starting point.