Prop suggestions....
 

Repropping due to new power and shorties...need some suggestions from those in the know...

1995 35 single step, blueprinted hull
IMCO extension boxes
-2 shorties
Appr. 550 hp each

With my old 502s and std length drives, I was turning about 4850 rpm on 26 Hydromotive quad 4 Xs....good for 73 mph.

Any info is good info...thanks.

Try what you have and just spin them faster but I have a feeling you are going to need 28 quad four X (round ear).
How many rpms does your engine builder say you can turn?
Allen

Maybe even a 27 or 28 Hydro P5-X

I've got to check on the rpms...I was thinking a 28 round-ear would be the answer as well...that's a stern-lifting prop, correct?

What would the diff between 4 and 5 blade be? Better bite on the low end for the 5?

Round ear propeller is typically a bow lifting prop. With the testing I have done with shorties we have never been able to get a pointed ear propeller to get on plane.
Typically
4 blade will be harder to get on plane (still pretty easy), will slip more and cruise and typically be faster on the top end. 5 blade will be easier to plane, faster cruise speed, slower on top end, and harder on drives.

What kind of speed are you realistically expecting and what gear ratio?
Allen

1:5 ratio (std Bravo). I'm looking at low to mid 80s, I would guess.

I have heard that Fountains like a stern-lifting prop? Keeps it runnnig level, which is a typical Beak-boat trait....

Ext boxes & shorties are too going to be hard on those std bravo. Keep in mine to keep an eye out for big gear sets or xr uppers. You will need them in time.

Mike, i have a feeling Dave will recommend propping somewhere in the neighborhood of 5400-5600 with the new motors. With the added HP, i would guess you will be able to spin your current props to around that rpm. According to the slip calculator, you had 8% slip. Thats good. if we assume 150HP additional HP, will get you an extra 600-800Rpm, and changing nothing, theoretically, you should be going around 83-84mph, turning your 26p props to around 5500rpm. The 2" shorties might increase slip, but also should increase speed from the reduced drag.

You have LOTS of props to try homie. Brian has a pair of 26 Hydromotive quad IV-X(bow lifters). You have your current props. I have a pair of Labbed 26P maximus 5 blades, lil D has 28p bravo 4 blades, and Andy has 26P bravo 4 blades.

Sooooo...get that sucker done, lets round up some props, and start prop testing! I'd really like to see you try Brian's props. I believe his will work really well. :coolcowboy:

Thinking about bringing the boat home this weekend or next...I want to really clean up the bilge and I have to pump out the old gas.

Mike, first see what the #'s are on the dyno. You don't want to spin the engines any higher than you need to. See where the peak torque is and then the peak hp, then you'll have a better idea on what prop you're gonna need. Right now, you're only taking a guess.

Let me know. I'll come help, and bring the car on fumes. :drink:

10x,
Say your motor peaks torque at 4600 and peaks in horsepower at 5600. Where do you try to prop your rpms to?
Thanks,
Allen

I've always tried to prop close to peak HP. But you need to be sure your valvetrain is up to the task. Propping too close to peak torque is hard on the drives, and can make for ill handling. I have a friend who ran 700hp 540's thru TRS drives for many years with no failures. He spun the motors around 5900. I think that was the key to keeping them drives together. Some guys cringe at the idea of anything over 5k rpm. A properly setup hydraulic roller can turn 5600-5700 all day. Solid rollers even higher.

Agreed!

Mike can't wait to see the new set up and go for a ride:evilb::drink:

Allen, Joe is right here. Generally speaking, your peak hp will be 1000-1200 rpm over your peak torque. If your peak hp is around 56-5700 rpm, you would'nt want to spin the prop much higher rpm than that. Guessing that you have bravo drives, rpm does'nt hurt the drives, it's putting a big load on them that kills em. They'll last alot longer spinning the props at 57-5800 rpm, than at 4900-5000 rpm at wot. You'll just lose some mid range cruise speed. The bigger the prop, the better the cruise, but you'll sacrifice speed on the top. I'm guessing that you would need something in the 26-27 pitch area.

10X,
I typed that wrong. Motor peaks torque at 4600 and makes peak horsepower at 5600.
Thanks,
Allen

Allen, I believe that's what you said the first time, you were correct, and that sounds about right. 56-5700 you'd want wot. :drink:

A set of bravo 4 28 or maximum 5 will due well. The max isn't as hard as you'd expect. You may want to try the bravos with the std lowers.

Mike, there's a pr. of 5 blade 28's Hydromotive P5X's in the swap section. Might be just what you'll be lookin for. Check em out.

Had a similar set up on our last 35... 1 step, standoff boxes, 585 hp per side, 1.5 gears, max hp at 5600 rpm... no shorties, though..

29 Quad IVs 65MPH @4500rpm, 76@5000, Hit rev.lim.(5600) 85mph

29 P-5's 72 @4500, WOT@ 5200 87.4mph

31 5bl(CNC) 76@4500, WOT@ 5200 90mph
Throttle up

Hope this helps, we ended up with the Throttle Up 5 blades, but a labbed pair of Hydro P-5's was very close in overall performance.
Carder

Keep in mind as set of bravo 30 pitch wheels done rite is the fastest prop for a fast boat. Not a really fast boat. As from my experience 6000 rpm. Is the roof for bravest, after that lowers puke,1:36 is also the strongest gear. Considering prop speed in your performance goal for handling purpose you may want to consider the upgrade.

Not up on the bravo stuff, but why is the 1.36 gear set the strongest ones ?? You sayin use the 1.36 with a 30 prop ?? Just curious.

Damn. Those numbers make me smile. :drink:

Yea they do. Makes me wish i had a step or two in my Hull :coolcowboy:

Mikey....I have standard Bravo 30's....let me know if you need to try them. I turn them around 5,000 with my HP500's and will most likely send them out to Brett at BBlades this Fall to be labbed.

Thanks Mike! I'll be in touch when it comes to test time. Got the boat home after towing on icy roads this Saturday...yeah...don't ever ever ever do that. Spent 2-1/2 hours PARKED on I-80 cuz some jackhole rear-ended a state trooper. Boat is absolutely filthy...just covered in road grime...I've got some work to do.

Get out there son with the hose and rinse off all that road salt! Trailer too! :eek:

Me too. :rolleyes:

Ugh. :eek: That is an absolute nightmare scenarios.

Yeah...need to do that. I think the origination of my problem, however, was the total LACK of salt on the roads!

Got my shorty lowers today...come on by some afternoon this week, Joe...

Now would be a great time to add the LED lighting in the bilge!

Yes it would!!!!

Already have some in the bilge...still haven't pulled the trigger on the underwater ones...they are just damn expensive...

:drink:

Hey mike, I wonder how these would work mounted on the bottom side of the swim platform? Not really underwater, but i would think would still give a nice little ambiance of red at night off the back...They use them as tail lights on boat trailers, and are fully sealed. I know i have dunked my trailers at night with the lights going, never had a issue. I may buy a pair and give them a try. For the money, its worth a shot! I have LED tailights on my semi trailer, and they get flogged with water when it rains, like holding a garden hose on them, never had a issue from getting them wet.

http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

due to ratio v.s torque applied. the 36 is stronger and if you have the power then use this combo. i would think he can use the 30 with the 1;50.

brett knows his stuff but maybe those 30's should go to scott over at merc. he has done atleast a half dozen sets for me, all on the money.

My numbers are back....569 hp, 622 ft/lbs. Looks like Monstaa might be on the money with the 30s...grabbing a labbed set from Kool-Aid Man for the sea-trial.

With the -2 lowers, this thing is gonna be a whole new animal.

TTT for Mike.

he now has some seat time with the new engines. Top speed is around 81mph with 26 hydromotives, turning 5600. he also got about the same out of 30p bravos, but a bit less rpm.

Im thinking even with the -2 imcos, he is still too deep with the boxes.....monstaa? Gets on plane no problem. no sign of roost at cruise or wot.