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  1. #1
    Registered
    My Boats:
    21 Formula 1985
    Join Date
    Apr 2011
    Location
    Miami Fl
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    15

    Prop suggestions for 1985 213 f3ls?

    Can anyone suggest a prop for a 1985 213 f3ls? Im running a 350cu. inch Mercruiser 260hp with an alpha 1 outdrive. W.O.T. shows 4300 rpm @ 44 mph. I know the engine should rev a little higher but I dont know which way to proceed. The prop says 19 pitch and nothing else. Please help!

  2. #2
    Back in another old BAJA VIP Member Baja226sport's Avatar
    My Boats:
    2011 16ft Tracker Grizzly 40hp....Fast!, Baja 280
    Join Date
    Mar 2003
    Location
    PA/MD
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    2,017
    Don't take it as gospel but I believe that motor should rev 46-4800 @ WOT. A 15 1/4 X 17P mirage should put you there.

    It will definitely plain off faster but I am not sure about top speed.

    I would think that boat should be in the 50 mph range though. That is if that motor isn't tired.

    I have a 21ft wellcraft I use for fishing w/ a 170hp 4 cyl that is turning a 19p mirage and I get 40 mph out of that.

    I would think being in the same size range (and most likely weight, about 3500 lbs) with almost 100 more hp you should be going a bit faster if it is running up to par.

  3. #3
    Registered
    My Boats:
    21 Formula 1985
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    Apr 2011
    Location
    Miami Fl
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    15
    Thanks for the response. The motor was replaced with a factory reman unit three years ago and currently has 211 hours. I thought that prop was a little to big for it. I hope to get it close to that 50mph mark. I will Try a 17 pitch out.

  4. #4
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    Join Date
    Mar 2008
    Posts
    172
    You'll likely get better results from a laser 2 than a mirage (plus) - a mirage has a good bit more blade area thanyou probably need to hold hte water where you're at in terms of weight and power. Just a thought... youmight be able to turn a laser 19 with a little more slip and more speed... and you do want your wot rpms around 4800...

    also, if you're exhaust is running through the (drive rather than through hull), playing with vented props can get you a lot out of the hole. Modern merc props like mirage and laser have the vents with plastic inserts and make it easy to experiment with the right size vent to get the best holeshot.

    Just some thoughts.

  5. #5
    Registered
    My Boats:
    21 Formula 1985
    Join Date
    Apr 2011
    Location
    Miami Fl
    Posts
    15

    Smile

    Well, I picked up a 17 pitch Mirage plus yesterday and will hopefully put her in the water tomorrow to try it out. Hope it works!!!

  6. #6
    Registered
    My Boats:
    21 Formula 1985
    Join Date
    Apr 2011
    Location
    Miami Fl
    Posts
    15
    I finally got to test the Mirage Plus and its way too much propeller. I could oly turn it 3900 rpm and 40mph. I'm trying an Enertia out. According to the mercury prop selector, it should push my boat 52.6mph. I dont need it to go that fast just run efficiently.

  7. #7
    Registered
    My Boats:
    1989 Formula 272 SR-1 1979 Formula 255 Liberator...My 4th Formula
    Join Date
    Jan 2011
    Location
    West Palm Beach, Fl
    Posts
    2,658
    In reading about prop selection on the BAM site, I came accross a neat prop calculator that they have...you might find it helpful. In addition I read about the effect that changing gear ratios have on prop selection. It is generally more efficient and better results are achieved by working the gear ratio as well as the prop pitch.

    Sometime you might consider changing the drive ratio on your Alpha from 1.5 to 1.65 and trying that Mirage Plus again. My brother has the same boat you do running 325 horse with a Holley 600 CFM Double Pumper. He found a great deal on a take off drive that had a 1.65 ratio in it and just for a try swaped it onto his boat. He is running a 21" Mirage Plus with vents in the hub. His hole shots are tremendous and his top end is around 55 at 5000 RPM running that combination.

    Best move he ever made...look for deals on drives here in South Florida...Alphas are everywhere and you can get a good one cheap.

    Also...make sure your engine is in good tune. Consider a good tune up with points/plugs/cap/rotor and wires....as well as timing. These things fade after a while and sometimes a good tune up can amaze you with the results.
    Last edited by sprink58; 06-08-2011 at 09:30 AM.

  8. #8
    Registered
    My Boats:
    1986 Formula F3LS, 1982 Laser 380- 200 merc
    Join Date
    May 2010
    Location
    Hernando, Fl
    Posts
    129
    My f3ls has 330hp 350 and spins a 21 mirage to 45-4600 which is about 58gps mph fwiw

  9. #9
    Registered
    My Boats:
    21 Formula 1985
    Join Date
    Apr 2011
    Location
    Miami Fl
    Posts
    15
    I called formula yesterday and spoke their service director to see what prop came on these boats originally. He went as far as looking into their older books and found out that they came with a 13 3/4 x 21 pitch aluminum prop. He also found that they used to use lazer 14x19 stainless props also. I went back to my prop guy and picked up a lazer 14x19 and will hopefully try it out this weekend. I'm not looking to get blistering speeds but would like to be able to run efficiently and top out somwhere in the mid to high 40's. Kudos to the people that work at Formula, They went above and beyond to help me out with my 26 year old boat.

  10. #10
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    My Boats:
    21 Formula 1985
    Join Date
    Apr 2011
    Location
    Miami Fl
    Posts
    15
    So I tried the Laser prop with 2 vent holes open and the boat jumps on plane instantly. I am now cruising 3000rpm 31 mph but will only turn 3900rpm wot at 42 mph. I'm gonna do a complete tune up this week and see if this helps a bit. It feels like the right prop but the motor just wont turn more rpm. Does anyone have any suggestions?


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