Mercruiser 5.0 4 blade to 5 blade help...

[lrdchaos]

I have a tahoe q71 with a bravo 1 1.62 gear ratio outdrive, 5.0 mpi. It came with a 19 pitch vengeance, I swaped that out for a 17 pitch 14.25 4 blade solas. I have a chance to pick up a 19 pitch 13 5\8 high five prop. My question is will I be able to run this prop? My concern is that I tried the 14.25 19 pitch solas and could only turn it 4500 rpms, I turn the 17 pitch 4 blade at 5250 at wide open throttle, so I'm a little overpropped. Would the difference in diameter, being that the five blade is smaller make a difference in rpm? Thanks


Also the 5 blade is vented, and my 4 blade isn't, what is the benefit of the vented prop over the nonvented prop? Thanks

 

[Bondo]

Re: Mercruiser 5.0 4 blade to 5 blade help...

I have a chance to pick up a 19 pitch 13 5\8 high five prop. My question is will I be able to run this prop?

Ayuh,... It'll be Close....

If necessary,.. A Prop Shop can beat the pitch up, or down slightly to tune it for you....

 

[steelespike]

Re: Mercruiser 5.0 4 blade to 5 blade help...

Read the stickies at the top of the page.
Any time you change props there are variables that can't be accounted for.
It appears you may have changed both brands and materials stainless to aluminum and 3 to 4 blades.Thus introducing even more variables.Generally a 4 blade improves low end performance
at a slight sacrifice of top end.
We need a base line prop size,max rpm and speed to make any reasonable judgement.I would suggest run the vengence and get us the info.
Also tell us what you are trying to accomplish, your typical activities and load.
Also need the max rated rpm of the motor.Usually on a label on the motor.

 

[lrdchaos]

Re: Mercruiser 5.0 4 blade to 5 blade help...

Thanks for the help guys, after talking with a couple of prop shops, I am going to have my 4 blade cupped a little more, which will bring down the rpm's200 and have vent holes drilled. I'm not gonna spend the money on the 5 blade.