ROTAX454

Quote from Articfriends: Stay away from the merc Maximus though as it will make a single torque roll like a sonufa*****, maybe a hydromotive , Smitty

Can you please elaborate on this subject?

articfriends

iTrader: (1)

When I had my stellings box on my single engine Baja and it was making 950 hp and about the same torque I tried a un-cut 28 pitch Merc Maximus vs a 30 or 32 pitch labbed merc 4 blade I usually ran and when I accelerated my boat would tq roll so hard it would almost touch the rub rail on the side to the water. When I -decelerated it would nose dive, transon lift and bow steer trying to swap ends. after several passes I sheared off a billet max worx prop shaft. It wasn't a productive test to say the least. I have been told Maximus props don't work real well on singles unless they are cut-down, labbed and prop center line is really high, I am a believer, Smitty

Dave M

I'm running a Maximus on my single engine boat. I saw significant mid range gains over a Bravo 4 blade. Top end is a few MPH lower than the Bravo, but so are RPMs. My slip numbers are very low with the Maximus. If I could ring a few more RPMs out of it, my top end should be there too.

I didn't experience the problems that articfriends mentioned. If anything, it reduce the torque roll for me.

articfriends

iTrader: (1)

Whats your prop C/L, I keep hearing that they only work with high c/l numbers and it helps if they are cut/labbed. What has been done to the one you run and what pitch/rpm/hp/gear ratio are you at, I love hearing about
others set-ups, thanks, Smitty

Dave M

I'm running a stock 26P Maximus, 4900 RPM, 525HP, 1.5 ratio. I'm getting around 73 MPH, which works out to 9% slip. I'd like to get the RPMs up to 5200. A bravo prop would still be slightly faster. But, the all around performance of the Maximus is worth a few MPH to me.

bbladesprops

We have done hundreds of Maximus upgrades and Labs over the last few years. I was involved with the development of the Maximus propeller in the early 2000's while still at Mercury Racing. The propeller actually was released quite different than the original designs. We were originally looking at a 5 blade Bravo 1 but found the current design to be better for a larger number of applications. The Hydromotive P5X is a direct copy of a 5 blade Bravo 1 with a different cupping design. It is 15"s of diameter and limited as to its applications.

Our most common Lab recipe involves changing the diameter to 15.25" along with thickness, pitch progression and cup work. Also the exhaust tube is shortened (that's a whole other story I have written about many times in this forum). The propeller has infinite possibilities. We have done 14.5" diameter P class race versions and 15.5/8" high X dimension 42 Fountain conversions and everything in between. Typical Lab results are 200-400 rpm and 1-4 mph. sometimes more. One thing for sure, the mid-range cruise speeds jump way up over a 4 blade. Just to be clear, the prop isn't for everybody. Low slip numbers with 4 blade props to begin with, typically mean slower top speeds. The mid-range most always will grow though.

Let me know if you have any in depth questions.

Brett

Itsallgood995

I tried a stock & modified Maximus 24P on my boat w/ the X @ 4.5” below. I didn’t experience the nose dive or body roll in either stock or modified form. It produced the same speeds as a Bravo 1 (true 24P) @ 600 less RPMs. Some have said a Maximus 24 runs more like a Bravo 28P. I don’t have the power to make up the RPM loss so its for sale in the classifieds if anyone’s interested.

JaayTeee

I have one ( propshaft) that that looks just like that too

UrbanDisturbance

My propshafts are twisted a little. I think they are about to break and look like yours. I have Maximus props with twin 600hp on bravo 1 with the one inch prop shaft. I hope to get rid of these brovo drives forever.....soon.....

articfriends

iTrader: (1)

How much power are you running, Smitty