Checkmate 242 Convincor with Built 502
 

I need help identifying what prop to use. Here are the specs of my motor, please offer any help you can. I currently have a 25P Quicksilver Mirage & I'm not getting the top speed I feel the boat is capable of, specs are as follows:

502 Bored 40 over stroked to 540
Dart Pro 1 Heads w/ ARP Studs
Quick Fuel 1050 CFM Carb
RPM Airgap Intake
High Performance Rings & Rocker's
SRP Flat top Pistons
Bravo 1 Outdrive
1.5 Gear
9:1 Compression
Estimated 650 hp
Estimated 740 Torque

I've been told several things, typically run a Mirage 29P or 30P, and one said a Bravo 1 28P or 30P 4 blade prop. Anybody got suggestions or recommendations?

Thanks,
Ken

I'm thinking you're pretty close to my setup, and a 28p Bravo 4-blade prop would be a good start?

Thanks, what kind of top end are you getting, and how many RPM's?

What RPM are you propping for? The builder should know that.

What is your current speed and RPM.

A lot of variables, (air/water temp, load, etc.) but 83mph @ (I think) 5200ish.
Turning a Lab-finished 28-P Bravo IV blade

Well the motor hasn't been broken in fully, so I was told the RPM's would rise between 600-1000 when the motor finally settles, we got 5200 RPM at 64 MPH, but will get some RPM's after adjusting the timing better. Everything I've read shows that I should be getting 80-85 mph.

You're right, sounds like a similar set up as I think that's about where I want to be...Thanks!

Based on those numbers, your slip in 22%. Is you prop in decent condition? I'd try a Mirage+ or Bravo 1.

My previous boat, 24 Superboat was turning a 28P bravo 1 @5000 RPMs with only 425 HP, 78 MPH.

I have a 522 with just over 600hp in a Velocity 280 and with the the Bravo 4 blade 28p I run 82 at 5200 without any trim, the prop blows out. I have a 27p Hydro-Motive 4 blade cleaver that runs mid 80's at 6000. I talked to Mercury Racing and they recommended a labbed 5 blade 30p at 15" diameter.

Thanks for the information guys. I'm tempted to contact BBlades & try there test program, I've seen some others post that they have had great results with them. But since the consensus is a 28P, I'm thinking about trying the 30P just to see what kind of results I can get & how well it can push it...

Anybody have any experience with BBlades & tried there loaner/test program?