Prop change rpm gain?

[Oldpos]

24 ft tritoon with 5.7l I/O engine 1.47 alpha gen II drive currently. 14 inch 19p stainless prop. New sized engine to the boat with no successful runs over 2600 rpm. I have another post in the mercruiser forum to trouble shoot engine issue possibly. When it had the previous engine 3.0l with 1.98 drive I ran a 16” 13p rpm 4600 at 23mph max. That’s before I put a third toon under it also.

My question is sort of broad , if I go from a 14” 19p stainless prop to a 16” 13p aluminum prop, how many rpms would it increase? I know both the diameter and pitch affect it so I have no idea what to expect.

Also what is this slip with the prop everyone keeps posting calculations of?

 

[alldodge]

Slip calculator
Enter info you have and then the one you want to find leave it blank and elect that button. Can also do things like what would happen if this one thing was changed
https://bblades.com/propeller-slip-calculator/

 

[Texasmark]

Go-fast.com is what I use and some folks use a Merc. calculator as I read on here. The calculator is to analyze how well your prop is connecting to the water. It's blind in that it only responds to changes in the listed areas. Changing anything else disqualifies your answer which includes prop types, load, hull changes and on and on.

 

[Scott Danforth]

not sure you can fit a 16" prop on an A1G2 as it was tight with a 15". however rule of thumb is 200 RPM for every inch of pitch.

still think you have a fuel issue.

 

[harcos]

not sure you can fit a 16" prop on an A1G2 as it was tight with a 15". however rule of thumb is 200 RPM for every inch of pitch.

still think you have a fue

24 ft tritoon with 5.7l I/O engine 1.47 alpha gen II drive currently. 14 inch 19p stainless prop. New sized engine to the boat with no successful runs over 2600 rpm. I have another post in the mercruiser forum to trouble shoot engine issue possibly. When it had the previous engine 3.0l with 1.98 drive I ran a 16” 13p rpm 4600 at 23mph max. That’s before I put a third toon under it also.

My question is sort of broad , if I go from a 14” 19p stainless prop to a 16” 13p aluminum prop, how many rpms would it increase? I know both the diameter and pitch affect it so I have no idea what to expect.

Also what is this slip with the prop everyone keeps posting calculations of?

That 5.7 should easily max out RPM's with that 19 pitch, silly question but is it a marine engine? Proper cam and proper ignition system. If it is an automotive engine that could explain the lack of RPMs

 

[QBhoy]

That’s a hell of a ratio for that set up perhaps. You can get a big bladed 16x16 black max prop that will fit no probs. I know plenty of big cruisers that run these on an alpha.
That’s if you can turn a 16” into the rpm range. You’re definitely way off with a 19” for sure. Some open smaller speedboats would struggle to turn a 19 well with that ratio.

 

[Scott06]

not sure you can fit a 16" prop on an A1G2 as it was tight with a 15". however rule of thumb is 200 RPM for every inch of pitch.

still think you have a fuel issue.

I remember look at an enertia eco was 16” that was listed as fitting my alpha gen 2