Phantom 25 1985 - 450R
 

Hi!

I hope everything is ok with you all.

I am going to buy a 450R next year. Currently I have a 400R on my Phantom 25. The boat runs 88-89 mph spinning a Max5 25 standard tube prop at 7,040 rpms. The propshaft is 2 inches above the bottom. In all approx 8 inches setback incl notch. The boat ran 81 mph on a good day with a 350 Sci spinning a REV4 25 prop at 6,500 rpms. Propshaft 2 inches below the bottom.

I am not sure how much gain I will get with the 450R, but if I am correct the 400R is pulling 390 HP and 450R 450 HP. So maybe 94-96 mph at WOT.

I plan to buy a Max5 27 pitch prop. What do you think? I presume its wise to test out the Max5 25 first but I expect it to hit the rev limiter hard then. Do you have other suggestions? A CNC 5 blade cleaver could also be the thrick, although its a very expensive prop. In Norway we need to buy to test ....

Have a good day.

Cheeers, Toffen

Referencing the high cost of marine parts and products in the EU, you can use the Max5 25P as your break in/ base line prop with the 450R.
From your base #'s you can dial in closer to the proper pitch combo... may not be the perfect answer but it keeps from spending your $$$ twice on a prop with no base line #'s to begin the dialing in the bigger power

Hi!

Thanks :) Good point. I will check out with the Max5 25 and see the rpm and speed. Most likely we will hit the rev limiter hard, but then we have a baseline how many rpms less we need. The peak power rpm is 6200-6400.

Cheeers, Toffen

It will be hard to tell how much you need to reduce rpm if its banging the rev limiter.
400R has a 1.75 gear ratio and 450R has a 1.60 gear ratio. Theoretically that will about 3" prop pitch difference and would equal about a 600rpm reduction with just the ratio change and assuming the same hp. With a 60hp increase, that equals about a 400-500 rpm gain. The 450R lists a WOT rpm of 5800-6400 so I think you are on track going with a 27" in the same make of prop.

Toffen talk to Randy Coursen "Wildman" on Scream and Fly. He is is setting up a 2nd Liberator with a 450r. The first ran into the 120s'. They have done extensive prop testing on the 300R, 400R and should have some insight and suggestions for the 450R. Randy is a great guy and is always willing to give good advice on setups. He helped me with my Talon setup.

Cheers Bob

Will do ! Thanks Bob ! :)