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Thread: Minx upgrade.

  1. #1
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    Minx upgrade.

    I have a "restored" minx with a 350 mpi and bravo drive. I bought it off this board a few years ago and while I like the boat it is a bit of a turd.
    Best speed form it so far is 59.2 mph.
    So if all goes to plan in the next few weeks, I am trading a friend my 350 mpi for his 502 mpi and my stock bravo lower for his -2 imco lower ( plus some cash)

    Anyone have any idea on how much faster it might be?
    also while I am at it I am considering adding stainless marine exhaust, thoughts?

    RT

  2. #2
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    IMHO I think that would be a tad a$$ heavy . Plus the 502 , I think , is a bit much for the boat's construction.
    A built 350 or 383 would be a better way to go I think .
    Just because something's old doesn't mean you throw it away !

  3. #3
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    Is there room for a Blower? Might get you close to a 415hp 502MPI given you will gain back a little over 1mph for each 100lbs of weight you avoid. Just a thought.
    1972 16 OB - C16B-63 - "Surface Tension" Resto Project
    1974 16 OB - DMR16106017-B - "The Mule"

  4. #4
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    My Minx w/a pretty stock 350 Vortec would do 65 on a good day.
    I really don't recommend a BBC in a Minx. The engine compartment is about 6"-7" shorter than a 22C engine compartment, and the hatch size is about the same as an 18C (the engine comes out sideways).
    My recommendation would be a pretty warm SBC w/about 400-425 HP and an Alpha.
    I believe this package would be good for 70-72 MPH.
    Understand, no one here has ever seen an 80 MPH Minx, so keep your expectations in reason.
    I think the extra weight of a BBC in the Minx would not be a step in the right direction.
    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

  5. #5
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    The boat already has a bravo, so there is no going back to an alpha. My old 18 had a 400 with an alpha ss, I am not a fan of small blocks.

    Years ago, hot knots in orillia ontario did an all red minx, called "red hot", it had a bravo and a 454 mag, 365hp. If memory serves it ran a 27 mirage prop to close to 5000 rpm. Math suggests it is or was close to if not better than 70. I was young but remember it being a fine ride, but it did chine walk and the owner couldn't drive it.
    My opinion is that a 454/502 with light exhaust isn't much different in weight than a stock 350.
    As for a minx over 80, in time I hope to be. I am just major league limited on time. My long term goal it to do a real resto-mod on the boat, core the hull blueprint the bottom, a reall stringer system and re-gel it. Then rig it to the hilt, I am major anal about my stuff and this boat in its current state is embarrassing.
    Oh and my sea ray runs 84, it doesn't seem right that the donzi is following it.

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    Screw the Minx...show us the 84mph SeaPig!
    Nick
    1994 22' Classic-454 B1 Red & white
    1981 13' Whaler sport(original owner)
    South Tampa Bay, FL "May I mamoo dogface to the banana patch?"

  7. #7
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    Pachanga 22, 511 CID, based on 502. Makes 570 ish hp on active engines dyno, 1:36 gears lab bravo 26 at 5800 rpm. Imco drive, steering and exhaust, would be faster if I removed the stock vernalift mufflers. They really snuffed the motor but it sounds almost stock. The only givaway is the oil temp, water psi and fuel psi gauges
    It is a fun boat

  8. #8
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    Only one way to find out .No Guts No Glory I'd say do it Bro!



    Jeff's Boat


    machinist ,bore it deeper,ream it bigger, and lap it to a fine finish



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  9. #9
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    Quote Originally Posted by RBT View Post
    The boat already has a Bravo. As for a Minx over 80, in time I hope to be.
    It sounds like you are looking to build the fastest Minx.
    1972 16 OB - C16B-63 - "Surface Tension" Resto Project
    1974 16 OB - DMR16106017-B - "The Mule"

  10. #10
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    Fastest, that never really crossed my mind but for reference what is the target?

    how does the Arneson powered boat run?

  11. #11
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    Your structure plans are the correct direction as the hull was never intended for more than about 350 HP. They all have hooks on both sides of the hull....except for my old Minx, and Jeff's Minx, they've both been fixed (there's a thread on here somewhere of removing my hooks).
    I also beefed up the stringers in mine, but not for 500 HP.
    But why you even bothered to ask the question of upgrading to a BBC, I was puzzled. You've obviously already made up your mind since you received three negative responses.
    I thought Greg's response was on the correct track as there's loads of vertical room under the hatch.

    I wish you well.
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    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

  12. #12
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    Yes I have made up my mind, I was more interested in what you all figure the speed increase might be.
    As for the hook, it is horrible. I can see it..... Passenger side is worse.

    My loose plan is to remove the deck. Remove the structure, vacuum bag in a balsa core, replace the stringers. Then flip it over and blueprint the bottom.
    I am going to add a full transom as well, as I want to add k planes and real steering. For now, the motor and lower as it is easy.

  13. #13
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    What are you planning to do about the CG ?
    1972 16 OB - C16B-63 - "Surface Tension" Resto Project
    1974 16 OB - DMR16106017-B - "The Mule"

  14. #14
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    nice shot of jeff's boat running

    so the Minx is not a 2 foot shorter 22 it is a 4 foot longer skisporter. I was surprised to see the short inner strakes on a production boat from the mid 1980's when the classics they were making at the time had longer inner strakes. I am far from nautical engineer but i would imagine that is why you don't see alot of fast minx's just like the skisporter they require a lot of power and the right setup to run above 65. wonder if that was done for a softer ride of a rounded keel with no lift and speed was sacrificed??

    good luck on your project
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  15. #15
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    I've pondered many times why the Minx doesn't seem to respond well. In so many ways it's similar to a Cig 20, but the hull is a totally different critter. Also, the Minx has quite a lot of frontal area to contend with. As speed increases, the parasite water drag decreases as the hull lifts out of the water and wetted surface decreases, but air resistance increases w/the qube of the speed.
    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

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