Swapping Props

[Toxicballsax]

I have a 93 115 Johnson ,it came with a 13x19 . Now off the last boat that had a 70hp it ran a real nice looking 13 1/4 x 15. What difference would it make running the old prop with a lower pitch ,but slightly larger diameter ?

 

[tpenfield]

Re: Swapping Props

Diameter difference being so small will not really matter, it is more about the pitch in this case. So, why would you want to go from a 19" pitch down to a 15" pitch??? If the 19" runs fine, then the 15" will surely over rev the engine. . .

 

[steelespike]

Re: Swapping Props

Agreed, the 15 will add 600 to 800 rpm will give you unbelievably fast hole shot but no top speed and you would have to be very careful not to over rev.
If you read the stickys at the top of the prop forum and get us the information requested we may be able to tell how your setup is working and if there is any tweaks you could do.

 

[jestor68]

Re: Swapping Props

What's it doing with the 19 pitch?

What kind of boat? If you go from a 70 to a 115 on the same boat, you will need to run more pitch.