Another prop comparison question....
 

I borrowed a set of labbed by Mercury 26 pitch Bravo 1 props to test on my boat. The boat ran 77.5 at 5400 rpm at the rev limiter with flat water and a full tank of fuel.

I lost four mph at cruise of 3100 rpm with these props compared to my 27 pitch Mirage plus props. However coming up on plane was awesome and pulled really well through the mid range. Is this just a factor of the lower pitch or does the extra blade make the difference of the holeshot?

The Bravo 1 props calmed the boat down some at WOT.

What can I expect from stock 28 pitch Bravo 1 props compared to the labbed props? I understand I will probably need to have the 28's labbed but would like to know what to expect out of the box.

Thanks
Brian

Re: Another prop comparison question....
 

The Lab Finished 26P Bravo I propellers should run like 24P stock Bravo I's. The 28P Bravo I pops will runn a MUCH lower RPM than the 26P somewhere around 400 RPM lower. What is your target RPM? This will determine what pitch you need. Lab Finishing will increase the RPM by about 250. The 26P Bravo I is approx 2 inches of pitch smaller than the 27P Mirage Plus. The smaller the pitch the better the hole shot. Additionally the added blade enhances getting on plane. The 27P had better cruise speed because it was lower in the torque band of your motor most likely and produces better cruise speeds.

Julie

Re: Another prop comparison question....
 

Julie,
Thanks for the information.

I would like to run right at 5000 rpm, these are stock 350 mag mpi motors with 5 psi boost prochargers. Sounds like the 28's in stock form will be close.

Is the 400 rpm difference between stock 26 and stock 28's or between the labbed 26's and stock 28s? Or do I need to factor in the 250 rpm for labbing?

When props are labbed you state it adds 250 rpm, is there also normally a speed increase or is this just to get the rpm where it needs to be?

Re: Another prop comparison question....
 

The 400 RPM difference is comparing a stock prop to a stock prop. Lab Finishing will produce an increase of 250 RPM. Typically you will see about a 2MPH increase in top end.

Julie

Re: Another prop comparison question....
 

Labbed Bravo 1 28's should put you right at your 5000 rpm range.

When we Lab those props we see a 300 rpm gain and have seen gains in speed from 0-8 mph. Every application is different. Gaining speed is one of the prime reasons for Labbing.

You should also gain some mid range cruise speeds.

You may experience some slower planing times.

The 27 cruised better than the 26 Lab because it is a higher pitch and full cupped propeller, as compared to the Merc Labbed 26 B1.

Re: Another prop comparison question....
 

Thanks for the input, I figured they would need to be labbed once I have the 28's. I should have them on monday. I will run them and then figure out what needs to be done and where to send them to be labbed.