Prop and Engine Performance

joe7670 · #1 11-08-2009, 09:55 AM

So I ran the 150 Opti with Mirage Plus 48-19838 15P.

I was able to get 5400 RPM at 38-39 MPH.

Does this sound right given that I'm reading that once broken in the motor gives a little more or should I be trying the 17?

spareparts · #2 11-08-2009, 10:24 AM

something doesn't sound quite right about those numbers, I would have guessed a little better performance, but I'm an optimist, I allways guess too high. Wonder if the motor is a little low on the bracket. Ferm? some input here!

Skools Out · #3 11-08-2009, 10:33 AM

i agree spare sounds low on speed numbers, i was figuring 42 to 44 with that setup and those rpm's

THEFERMANATOR · #4 11-08-2009, 03:05 PM

The speed numbers do sound a tad low for a 150 OPTIMAX as that is a strong 150. Then again though I don't think the MIRAGE is an ideal prop for speed on a V-20. It is a very efficient prop with alot of bite to it which is good for offshore, but that large diamtere can actually cost you up high. I know my HYDRA lost a tad on the top end with my MIRAGE copy, but it gained alot at cruising. I would say a REV4 or ENERTIA would be a better match. Also from looking at your videos I would say don't be afraid to trim it up some more for top speed. You were running pretty flat in them and it looked like your engine was at a neutral to negative trim in them when you ran it up. For max speed you want to get the engine as high as you can without the engine cavitating or the bow blowing over. Check your engine height first as that can change alot of variables right there. If you are going to be doing alot of slow speed's and cruising offshore I would keep the MIRAGE, but otherwise I would reccomend a REV4 or ENERTIA to try.

captpete13 · #5 11-08-2009, 06:30 PM

I'm using a Merc Laser 2 on my boat. It works great. I wouldn't rule that one out either.

THEFERMANATOR · #6 11-08-2009, 07:01 PM

http://www.propgods.com/content/propellers.aspx

This will give you a basic idea of what MERCURY's props do. Check your engine height first, and if that is good see if you can find a 15 pitch ENERTIA. You may actually need a 17 pitch with it though, and remember that every prop will have a different engine heght it likes. Some like to run high and cavitate a little, and others have to be buried in deep all the time. I would think with the bracket though you would want a sternlifter as bow lift would be a problem on a sloppy day.

When checking your engine height you will need 2 people. One person drives and the other goes back and looks at the engine. You want to be able to see the caviatation plate just a little bit as a good starting point and go from there.
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