To Sum Up

Discussion in 'DIY Marinizing' started by DogCavalry, Oct 14, 2019.

  1. DogCavalry
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    DogCavalry Senior Member

    As follows
     
    Last edited: Oct 18, 2019
  2. upchurchmr
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    upchurchmr Senior Member

    Many of us have made the same comment, on different subjects.
    Good luck.
     
  3. upchurchmr
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    upchurchmr Senior Member

    It is difficult to always know what is meaningless.
    From my experience, some posters don't offer background on their comments or their experience.
    That sometimes only comes out when they are challenged.

    So some comments at first don't seem useful due to them being too simple.
     
    Last edited: Oct 14, 2019
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Your point being..??
     
  5. gonzo
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    gonzo Senior Member

    Automobile engines are used in marine applications in the millions. Have you ever lifted the cover of any smaller boat with an inboard or I/O?
     
  6. gonzo
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    gonzo Senior Member

    Yes. Why do you claim automotive engines are not used in boats? There are some changes, but not on the basic design or functioning. Auto transmissions can not be used unless there is a thrust bearing installed on the shaft. Otherwise, it will fail very quickly. The electrics should be spark protected if the engine is mounted inside an enclosed compartment. You will need some way to cool the engine, and an automotive radiator will work just fine if you can live with the heat.
     
  7. gonzo
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    gonzo Senior Member

    You can buy all the components to marinize and engine off the shelf. However, it is usually cheaper and simpler to buy a used running engine, or rebuild and already marinized engine. There are thousands of used engines in North America.
     
  8. Ad Hoc
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    Ad Hoc Naval Architect

    You will not be running the prop directly from the engine. Therefore you will have a gearbox. The gearbox needs a thrust bearing added. But you could simply buy a marine gearbox from the start, which solves this problem.
    The cooling, depends really on your objective for use, slow inland water ways, or out at sea and going full chat. So add a closed circuit fresh water system and fit a heat exchanger. Seawater is pumped through the heat exchanger.
    Then if the engine is run for long periods, you need oil cooling for the engine.

    I would strongly recommend you buy this book, marine conversions. It says it all and how to convert an auto engine for marine use and presents options based upon your budget.
     
  9. gonzo
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    gonzo Senior Member

    They do, and call them reverse gears. Volvo gears, among others, can be run in either direction. The operating parameters of a planing boat are similar to a car, fully loaded going uphill at all times with the throttle wide open. You would not be changing gears. Saying that the marine environment is comically easy on transmissions, makes me think you don't know much about marine mechanical design. If it was as you say, there wouldn't be so many transmissions with busted gears and worn clutches. They absorb the same power and torque as the car transmission in the previous analogy.
     
  10. gonzo
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    gonzo Senior Member

    You can't do that on a boat, because it goes uphill in all directions. Cars go uphill and return downhill. I take offence at you saying it is piss poor engineering. What have you designed and built? You obviously have no clue about fast high performance boats. For example, the only way to control an airborne boat is by accelerating/decelerating the engines hard so it is level when it hits the water. Therefore, reverse turning.
    As for water being softer than mud, just look at a snapped propeller shaft; not by grounding.
     
  11. Barry
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    Barry Senior Member

    Often throughout the years, OP's have brought up the idea of saving some bucks on taking a automotive engine and marinizing it.
    If you don't value the life of yourself or your companions and do not have to have the boat surveyed to get insurance, yes you can save a few bucks.
    But for those of us who require a safe boat here are some of the things that an automotive engine needs to be marinized.

    1) Fuel pump - if not a spark arrested electric fuel pump, then a mechanical diaphragm pump that has an attached vent hose to the
    intake to capture the fuel if the diaphragm leaks
    2) A spark arrested alternator
    3) A spark arrested starter
    4) A spark arrested distributor - and if you have two engines, the counter rotating one needs a corresponding marine distributor with an additional
    thrust bearing under the shaft
    5) Raw water pump - to push water from the boat through either a fresh water heat exchanger or the watercooled manifold and risers
    6) Watercooled manifolds- - to keep the engine compartment and or metal cool
    7) Watercooled risers - to ensure that water will not back up into the exhaust valves, and provide a place for the raw water to enter the exhaust to
    keep it cool
    8)Cam shaft - often, maybe not in the last several years, the engines may have a cam that pushes the hp to either a higher value or a modified
    horsepower curve
    - with a second counter rotating engine, you will need a modification of the timing chain drive to change the
    the cam shaft direction
    9) Bronze frost plugs -merely for corrosion protection
    10) Heat exchanger- - while not always required, a heat exchanger separates the engine water jacket from raw water issues, ie sediment ingress or the
    introduction of corrosive salt water. Additionally, it provides the opportunity to keep an anticorrosive antifreeze against the
    block internal passages and keep the engine from freezing
    11) Hoses - with all the myriad of water cooled exhaust manifolds, risers, heat exchangers, raw water pump and maybe even a
    freshwater oil cooler, not mentioned above but often comes from engine marinizers as standard fare.
    12) Flywheel or Ring gear- On almost all of the engines that we purchased from a professional source, they only provided a ring gear for the
    starter to engage. Mainly to remove the weight of the flywheel.
    13) Motor mounts - most engines will require a set of motor mounts that will allow alignment in your boat and often a little stiffer to keep
    the concentricity from the crank shaft to the prop shaft, jet shaft etc a little tighter
    14) if carbed - a marine carb vents the float bowls back into its throat

    15) if carbed or efi - a flame arrestor to ensure no flash back in the event of a back fire

    Now I am sure that I missed something but that is what marinizing an automotive engine requires to turn it into a marine engine.

    So assuming that you are going to do the conversion right, unless you can buy the parts at prices much below wholesale, you are unlikely to be able
    to produce a marinized engine below the price that you can buy one from some of the companies out there that do this for a living.
    KEM equipment, Redline and there are many more offer engines at online prices that are cheaper than what you can do yourself, plus they come
    with a warranty.

    Forgot to mention that many of the marinizing companies are supplying roller rocker in many of their engines. Additionally, Merc has a remanufactured program that can even save you more money. In Vancouver, you could also try a couple of companies who manufacture jet boats who might give you a good deal on a new engine as they save money on bulk buys as well as freight. Ask to see if they may have any Velvet Drive
    transmissions as some of the marine engine conversions come with a tranny and
    these are often removed upon installation
     
  12. Ike
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    Ike Senior Member

  13. Ike
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    Ike Senior Member

    Maybe neither. The one with power to go 40 probably has a much smaller and lighter engine. The one that can go 60 more than likely has a much more powerful and heavier engine. Plus that you are missing something here. Speed has a lot to do with hull design. If you take a boat designed to go about 40 with a properly configured engine for that boat, it will not go 60 even with double the HP. you may gain a few mph but at the expensive of a lot of fuel and putting the boat in danger of doing dangerous things like chine walking, kiting, instability at speed and so on. A boat has to be designed for the speed and power you want.
     
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  14. Ike
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    Ike Senior Member

    In the army you may call that evasion but in the Coast Guard we call it good engineering. And I might add there is no way you are going to go from 40 mph to 60 just by changing to a free flow air filter. Besides most boats have flame arresters that aren't filtered. High performance boats use filter/arrester combos but most boats don't
     
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  15. Barry
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    Barry Senior Member

     
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