1984 Thundercraft Magnum 230
Engine: Merc 260 (5.7L) serial 6846787 RPM 4200-4800
Stern Drive Alpha One serial 6847830
I just bought a new Black Max new design prop with a Plastic Hub Kit to fit my Stern. I do not have to P/N since it is not on my bill but;
4.25'' dia x 21 pitch (new blade shape)
= Top speed 38 MPH at max 4300 RPM (speedometer)
I replaced the prop for a other New Black Max
4.5'' dia x 19 pitch
= Top Speed 32 MPH at max 4100 RPM (speedometer same day))
I am trying to reach max RPM and I can't. The store that sold me the props told me I will get 500 RPM more with the 19 pitch prop. And I didn't. He will replace the prop again, but I'm starting to dought about his competences.
Why I'm I loosing speed and RPM with the 19 pitch prop?
Engine: Merc 260 (5.7L) serial 6846787 RPM 4200-4800
Stern Drive Alpha One serial 6847830
I just bought a new Black Max new design prop with a Plastic Hub Kit to fit my Stern. I do not have to P/N since it is not on my bill but;
4.25'' dia x 21 pitch (new blade shape)
= Top speed 38 MPH at max 4300 RPM (speedometer)
I replaced the prop for a other New Black Max
4.5'' dia x 19 pitch
= Top Speed 32 MPH at max 4100 RPM (speedometer same day))
I am trying to reach max RPM and I can't. The store that sold me the props told me I will get 500 RPM more with the 19 pitch prop. And I didn't. He will replace the prop again, but I'm starting to dought about his competences.
Why I'm I loosing speed and RPM with the 19 pitch prop?