5 blade props for the Bravo 1 drive
 

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?

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

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.

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

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.

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

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.

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

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.....

How much power are you running, Smitty

Good point...I'm less than half the power your putting out. appx 420hp @ best

I was curious, with my limited experience with the Maximus on my boat I am convinced (and have been told by the prop experts) the tq roll I expererinced with my set-up is related to having a extreme amount of tq on a single engine boat combined with the Maximus prop I tried was un-cut and NOT labbed. My boat also tq rolls with un-labbed 4 blade bravo props too. Smitty

Smitty, I have received the new Gen prop shafts from Aaron. Being installed soon in my IMCO -2 lowers. In fact, both shafts (vertical and prop) are MAX WORX products.

Appreciate the information from all on this thread. Helps to understand the working perimeters of the 5 blade prop.

What prop are you using now? I tried a 5 blade Cutting Edge over Labor Day & liked it overall. I returned it for some fine tuning & should have it back it next week. Can’t wait!

Keep the five blades and get rid of the B-1's. I have 5-blade 34's on SCX's and i can mash it

I run a 30 pitch merc labbed 4 blade most of the time, a 32 labbed 4 blade for speed runs. I have 2 of the 30 lab's and sent one to Cutting edge for his special treatment, I ran it last weekend but have no real results to report as I am still shredding blower belts and only making 5-9 psi of boost and am barely breaking into the 90's where my boat with full boost usually can hit mid 90's pretty easy. Got more belts ordered and going to modify my new tensioner and see what happens before winter comes, Smitty
I would love to run a 5 blade but it's not in my future with 1000 plus ft lbs of shaft breaking torque!

Talking to Greg Hittner/Cutting edge props and a few other guys he has done work for I am hearing guys are getting great results with his 5 blades too. If I ever switch to a drive that will hold over 1000 ft lbs of tq at less than 10% slip I would definately try one. I am modifying my new blower tensioner in next few days and will be trying the 4 blade that Cutting edge worked for me recently and will report soon on that too, Smitty

I was able to get 10% once with a Quad IV in about 1’+ chop after I raised the X. The Maximus & Cutting Edge were both @ 19%. I just received the Cutting Edge back today so hopefully that number will drop. I’ll know by the end of the weekend.