Help me pick a prop!
 

Hey guys, I have a 97 Fountain 24CS with a 454 that has Heads, Cam and an Intake with a Holley. It has a Quicksilver Mirage 3 blade 26P and its turning out 70mph at 4900rpm with about half tank, no tabs and trimmed properly. I have seen 72 with less fuel and very calm water. The biggest issue I have is it takes way too long to plane and I feel like the prop blows out when I accelerate too quickly before it planes out.

I want to switch out to a 4 blade for quicker planing and better mid range. To make matters a tad more complicated I'm about to install some CMI E-Tops so I'm not sure what pitch and brand prop to get to have her turning at 5k rpm at full tilt... Thanks in advance!

Bueller...? Bueller...?

Im assuming you have a 1.5 ratio drive so your slip percentage of 12.97% is pretty good, as I have always heard fountains tend to be on the higher side for slip percentage. I have noticed alot of guys running hydromotives on fountains. I would try a 24p Q4x hydromotive or a 24p Bravo 1. Those should plane you out better, better acceleration, and will probably put you close to the same rpm you are at now. The 24p Bravo 1 should give you a little more rpm then the 24p hydro as the Bravo 1 is a little smaller diameter, and under pitched more like 23.3p where the hydro are closer to true pitch. But the hydromotive is a little bit better of a high x dimension (drive doesn't sit real low in the water) over the bravo 1 which is why I would imagine the fountains run them. Good luck, and if it was my boat this is where I would start, I also would give BBlades a call to get there input, and maybe there prop trial program may help you if you don't have the props handy to borrow.

Great! Thanks for the reply! I did in fact order and receive a 24P Bravo 1. I was just concerned about adding the headers and what that might do to my RPM. Do E-Tops generally add a lot of top end RPM if nothing else is changed?

What are you running now for exhaust?

Stock manifolds with captains call...

changing your exhaust wont give you enough power to worry about a prop change unless you already running 5200 with a 5250 rev limiter

Perfect, that's great news. Thanks for the replies.

Running a bravo 3 with mirage 24p on a Baja 260 with a 454... Previous 454 I was turning 5,000 Rpms running around 58-60 mph... Broke a crank so I put a new engine with same heads, intake, carb, different cam... I can only turn about 45-4600 Rpms and run about 46-48 mph... Can someone help me get some more speed out of this... Any ideas?

I personally would just wait till I got the exhaust on and then prop it to where I wanted it instead of trying to guess how much you will get from the upgraded exhaust. There are aeveral factors on how much the exhaust will gain you over stock manifolds. How big your cam is, usually stock exhaust is no good with a cam unless it's pretty mild, reversion is the issue. Heads, and your induction play a roll as well. But with CMI e tops and generally speaking probably 200rpms over stock manifolds.

Thanks for the input. I had actually already ordered a B1 24P before I decided to order the headers... The mod bug bit me and as we know it doesn't normally bite at the best time. Haha.

I put the new prop on yesterday and it's a night and day difference from the stock previous 3 blade 26p. It planes in half the time and feels much faster mid range and even to top speed... I didnt loost much top end. Maybe 1mph and it gained about 300 rpm. It's like a totally new boat! Love it even more now! Hopefully the headers help out even more. :)

I'll be watching your threads closely, I feel that I'll need a new prop after I get my engine back.

I have a 28p Bravo1 on my boat 24cs with 600hp. Haven't got to really run it out yet do to crappy water every time we have taken it out! I'm curios to see how it does.

I bet that 28p is spot on for 600hp. Let us know how it does when you get it on the water...

We are going to Lake Somerville August 22-23 for Rocking the Cove. So hopefully I can find some smooth water to run it out a little.

Well got a chance to run the boat some more, discovered a oil leak, and a leak on one of the trim tabs. So no all out passes, but did get to stretch it's legs a little. She ran up to 67 and had allot more to go. At around 2200 to 2500 it cavitates allot. Seems to go in and out. Talked to a good friend who has been around Fountains, and he said that the Bravo I have is probably the wrong prop. So I'll run what I have for now, and continue doing my homework on prop options. The biggest problem I have ran into was people not being real familiar with the 24CS.

Dale - the short block that You bolted your heads and part on - did you buy one for a car?
You probably have too mild of a cam.

Any updates here?

Well I have been working bugs out of my combo. Got to run it a couple of weeks ago, have a oil leak to fix, then it's time for some serious runs. It turned 5 k with the 28p on it no problem. I still had some throttle left in it, but I was running out of water. So I'm close to having some useful info soon.

I bought a 28 hydromotive Q IV to try. My test report says the 502 mag spun a 27 Q IV out, so hopefully my new 509 will wind out a 28.

Is it possible to edit a thread title? Adding 24cs to the title would be nice.

I contacted Pier 57 about the 24Cs that they built. ( Extremely nice people) It was 550 hp 502. They used a bravo 28p labbed by BBlades. So I will hopefully get a good test pass and see what I have. A local prop guy told me mine had been worked, but he didn't know what had been done to it.

Did you do anything besides taking it to a 509? going from a 502 to a 509 isn't gaining you anything power wise that you would notice, maybe 7hp. A 28p hydro is ALOT of prop if its relatively close to stock power.

The compression was raised and it got a lumpy cam with stainless marine exhaust, valve job including roller rockers. Couple small things, aiming for the 500 HP mark.