What Prop??
 

Just finished my 94 Checkmate 253 Convicor & need a baseline on whatprop to run. It has a 489 stroker with a bravo 1 . The engine is in the 525 to 550 hp range & it has 1:50 gears in the outdrive. I want to run a 3 blade & was wondering what a good prop pitch would be for all around performace.

Re: What Prop??
 

Are you determined to run a 3 blade? I would say you would get the best performance from a labbed 26" Bravo 4 blade.

Re: What Prop??
 

My cousin is selling a labbed 27 p hydromotive that would probably work great on that boat. Olders check respond really well to hydros. Let me know if your are interested. I think he needs $350 for it.

Re: What Prop??
 

Not set on running a 3 blade I just thought they make a boat run faster then a 4 blade. Also not sure on the 4 blade in the turns do they bite to much & not allow any slip. I really don't know so any advice would be appreciated. Thanks

Re: What Prop??
 

They run much more stable at speed and the cornering was night and day better with a 4 blade on my old 242 convincor.

Re: What Prop??
 

I agree. The difference is night and day. They slip alot less, better midrange, better holeshot. The down side, maybe a touch less top end. However, all in all, a better running prop. In fact, when I had stock power, I liked my 4 blade so much, I opted for a 5 blade when I upgraded power.

Re: What Prop??
 

Know anybody looking for a labbed 27 let me know the prop is mint!

Re: What Prop??
 

Vinny,
What topspeed would your 454MAG run with the 26 4 blade and at what rpm? How did that compare to the 23 Mirage Plus (mph/rpm)? We may add Tyler Crockett's 454MAG Upgrade Kit this winter and need to reprop the additional 100HP.
Rob

Re: What Prop??
 

Rob,
With the exception of Gil exhaust, adjustable fuel pressure regulator, vortech flame arrestor, my 454 magnum was stock. I could spin a 26" Labbed Bravo 1 to 4950 rpm. Speed was 66 mph on gps. Worked out to about 13% slip. I tried a 3 blade Mirage once. If I remember, it was a 25". BUT, it was a bit beat up. It was not labbed and had been abused. The results were terrible. I dont remember speed #'s, but I remember hitting the rev limiter and not going any where fast. I never had the opportunity to try another.
What prop are you running now? I have tried my labbed 26" Bravo with my 540 engine. It works well also. I keep it for a back up in case I need it. With this engine ( 680 hp) I can spin the Bravo 1 prop to 6000 rpm @ 80 mph. About 14% slip. However, I chose to run a labbed 25" Hydromotive P-5X. I had the pitch dropped a bit. I can spin it to 5700 @ 80 mph. About 9% slip. Not much of a difference between the 2 as far as speed #'s. BUT, the ride is better with the 5 blade, so I kept it.
I am looking to try a -2 Shorty lower soon. I may soon be able to borrow 1 for a test session. I'll post results if it happens.

Vinny

Re: What Prop??
 

I am currently running a 23 Mirage Plus (3 blade) at 5100 RPM resulting 65mph WOT GPS. The 454MAG is currently stock. I am thinking a 26 4 blade may be a good option with 480 propshaft HP. The upgrade kit includes exhaust, cam, heads milled .020 and ported, fuel pump, and reprogrammed ECU.

Re: What Prop??
 

Rob,
Sounds like a good way to go. Tyler Crocket certainly has a great repuatation. Another thing I would look at upgrading would be those $hitty non-adjustable rockers with the 3/8" bolts that come stock on that engine. While the heads are off, look into the possibility of drilling the holes in the heads to 7/16" and installing a good set of ARP studs. Then maybe a set of Comp Cams Pro Magnum roller rockers.
The additional 100 hp will certainly make a difference. However, what also is very important is torque. I dont know what the 454 magnum made for torque or what the curve looked like. I would ask Tyler for those #'s as well. If you look at my upgrade, from stock 385 hp ( which is actually 415 hp) when measuring crankshaft hp like my 540's dyno numbers, I jumped up to 680 hp. So I added about 265 hp and tons of torque. I netted about 14 mph increase of top speed. But, what really feels better is the midrange. If I am cruising at 4000 rpm and hit the stick, I get planted in the seat, the 454 Magnum didnt have the punch. The additional torque from the larger displacement has alot to do with that.


Vinny

Re: What Prop??
 

Additional head parts include roller rocker arms, rocker studs, roller camshaft, new pushrods, timing chain set, 2.250 severe duty intake valves, 1.890 Inconel Exhaust Valves, valve springs, retainers, locks and seals. Tyler did send a dyno run and peak torque with the kit is 569.7 lbft at 3800 rpm.

Re: What Prop??
 

Thats what I like to hear, sounds good to me. :D

Re: What Prop??
 

fast willy,
alot will depend on what rpm range your running in too,
my 242 convincor would only spin a 23, but i was able to spin it to 5600 rpm where i needed it......so as others have said if you want to keep rpm in check....like 4900 to 5100 then yes a 26 bravo, 25/27 mirage would be good.....

kevin

Re: What Prop??
 

Since you guys are on the subject, I have a 1991 251 that I'm repowering. Best GPS speed I could get out a modified 454 Mag using a labbed original 23' Mirage was 72 mph. I know that speed sounds high, but the 251 has a very narrow beam and weighs in at only 3700 lbs dry. I'm repowering with a new 540 that Gellner Engineering is building for me. It should make somewhere in the 625 hp range. I need to prop it for 5700-5800 rpm. From your guys experience, will the 27' labbed Hydro your talking about work for my application?
Also, what steering do you guys recommend? I'm considering an IMCO dual ram system. Any feedback is appreciated. Thanks

Re: What Prop??
 

I would recommend you go with Imco's dual ram full hydraulic steering. What drive are you running? What ratio? Which Hydromotive are you referring to 4 or 5 blade?

Re: What Prop??
 

Thanks for the feedback.
My drive is a 1.50 Ratio.
For the drive, I was referring to the 27' 4 blade hydro.
How has your drive been holding up with all of that power?
Thanks

Re: What Prop??
 

Sorry, my drive is a Bravo One. I have only needed to do general maintenance thus far - regular lube changes and greasing the u-joints.

Re: What Prop??
 

That 27" 4 blade be ok. It depends on where your want to run the engine. You need to look at the dyno sheet. I would try it to get a base line and go from there. Just be careful not to over rev the engine. I have a bit more power than you are planning on. Although are hulls are different, I can run a labbed 26" Bravo 4 blade and get away with it. See post # 10. Remember, a 26" Bravo is actually 24 1/2" pitch.
Drives.... now they are a major problem. I assume you are running a standard Bravo 1. It depends on you driving habits, but dont expect that to last long with 625 hp. Even more than that, is who had their hands in the drive last. I found out the hard way that some people who claim to be drive experts are not. I have broken shafts , worn out gears, had seals leak, wiped out bearings all in 1 season of 60 hours run time. That was last year, the first year with the new power. Disgusted with all that, I learned ( with some guidance ) , how to rebuild and set up drives myself. So far this year, I have 50 + hours without a problem. I am running an XR upper and Imco lower. I run hard but am careful with the holeshots and launching over waves.

Re: What Prop??
 

Vinny,
Do you think a labbed 26 Bravo would work well on a 259 Convincor with 475 propshaft hp? Peak hp will be achieved between 5100-5300 rpm.
Rob

Re: What Prop??
 

Rob,
I think that will work fine. Take a look at the #'s I had in post #10. You may get an idea of what to expect by using the #'s of my stock 454 magnum with a labbed 26" Bravo. Just allow for 90 more hp and I think you will be at your target rpm. Our hulls are identical, the data should be good.

Vinny

Re: What Prop??
 

Thanks for the responses. I'll let you guys know how it all works out. First things first, I need to get the engine back in and add on some steering. I then plan on rebuilding the drive. I have owned this boat for 15 years and haven't had any misfortune with the drive as of yet.

Re: What Prop??
 

I need to try a 26 bravo 1 labbed on my 280, I was bumping the Rev limiter this pasted weekend in cooler temps. I really think my 500 efi can spin a 26 lab and gain some speed in the process.

Re: What Prop??
 

Magic,
What prop are you running now? What is the rev limiter set at?
Rob

Re: What Prop??
 

I am running a worked 24 Bravo, not sure what is done to the prop it was on the boat when I bought it. I think that the REV limiter comes in at about 5250 rpm. If I keep the boat, I am going to have the ECU reprogramed to lean it out on the bottom end, it is really rich at idle. I would also like to raise the REV limiter.

Re: What Prop??
 

Fast Willy,
howd the testing go? did you try some props......

It's been a long road to acheiving what I expected. The boat ran good last year but had a rear main seal leak. So this year May of 07 we finally got her running good. We ran a 23 3 blade & it ran 71 mph on GPS. So I now just picked up a 26 4 blade & will give it a try this weekend 6-2-07. I'm just looking to get alot of trouble free hrs. run on the boat, but will occasionally push it to the limit. This weekend we are going to give it a good run down the ocean from Indian river inlet De, to OC, Md inlet. Finally going to let it stretch her legs.

the 253 hull likes the hydro prop. i ran a 27 hydro on my 97 253 with 560+ hp.

Magic, does your cousin still have the 27 Hydro for sale? My new 540 made 610 H.P. and needs to be propped for 5700-5800 RPM. My boat is a 1991 25' Convincor with the narrow hull. Will that prop work for my application?

The prop is primo. Contact Wild Willy he bought it from my cuz last fall. Should work on your boat.

Guys, just to get this straight...the 27 Hydro is a 4 blade and will mount to my 1991 Bravo drive? Is it a solid hub? Also what is the pitch comparable to?...25 pitch? Thanks

Wild Willy, can you send me a picture of it. My email is [email protected]. Thanks Steve

It is a lab finished 27 pitch. Hydro props are true pitch prop, unlike bravo 1's. Will mount to your drive no prob, we ran this prop on a blown 468 in a 89 Check Enforcer. Boat ran a best of 84 gps.

Wild willy is the 27 Hydro still for sale? If so let me know, very intrested.

Local guy just let me borrow a 24 hydromotive. I will let yo8u know.