Somewhere to Start
 

Need Props!

I Have to see if you guys can help me with a starting point.

Motors Crusader 330's or MK IV, 454

My O.E. Prop was a 17inch x 18pitch 3 Blade Nibral, 4400 rpm about 28MPH

Prop last year was a 18inch x 18pitch 4 Blade Nibral, 3800 rpm
about 33MPH No more Engine left to go any more RPM "overproped"

Now this year i am Stroking motors to 496's bunch more torque and some where around 500 something HP around 5ooo RPM Bob M is setting up cam and some other stuff. These motors are full roller with nice stuff in them "not Cheep Stuff"

so I know i need new props now I dont want to run motors over 5k. so 4500 or so. i would like to see if i can get this boat up to and hopfully over 40MPH. now on to the boat...

88, Trojan 10 Meter around 33ft. Dirrect drive.72C transmissions with 1:52.1 ratio. "Inboards" Weight about 16,000 full. I dont have a fly bridge

Any help

Start by running what you have. We can modify the current propeller to gain rpm. I don't know if we can get to the rpm you need with them but a starting baseline is needed.

Taking the 18" diameter down to 17" will give us a few hundred rpm plus the new HP might just hit your target.

Brett

thanks for the reply. you recommend going back down to the factory prop size? with the increse in torque and hp i would have thought i could go bigger!

so do you think i can achive 10 more MPH or grater.

Talk to Brett, hes the man

If you are going to make 500hp out of stroked 454's, you will have to spin the engines to at least 5000rpms.
Talk to Bob M about what rpm the engines need to run to make the power.

You ran 17's and the boat attitude was good....I guess. So, going to that diameter gains us R's. We need base line info with the new spec. to make educated decisions. All else is theory with this type of set up.

Brett

Bob is doing the build sheet so far he has not seen a problem
making our power down below 5K

I now have the cranks,rods, pistons.... bought the AFR 264 CNCd heads with heavy spring and the morel lifters from BOB M....Cams being profiled.

he thinking 500-520hp but gobs more torque

i guess i can start with the props that i ran last year 18x18 4 blade see what we get. they were 600rpms shy of their mark

I'm suggesting we may be able to use the propellers you have once they are modified. We can't determine a modification recipe without new engine base line performance numbers. Therefore let's try what you have to learn and then go forward with that information.

Brett