Turbo 400 trans or other Multi speed transmission with Surface drive.

Discussion in 'Inboards' started by MRover, Apr 27, 2021.

  1. gonzo
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    gonzo Senior Member

    Then, what is the purpose of the project?
     
  2. jehardiman
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    jehardiman Senior Member

    Hold up for a moment...there is an important difference between a GM Turbo-Hydromatic and a MOPAR Torqueflight. The MOPAR is shifted on torque converter pressure, the Turbo-slide is shifted on manifold vacuum. Only GM Hydromatics (late 40's to early 50's) use fluid pressure. The Torqueflight is better for a marine application due to prop unloading issues in a seaway.

    Ok, carry on.
     
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  3. cracked_ribs
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    cracked_ribs Junior Member

    I knew a guy who had a boat with an old GM Powerglide 2-speed with a manual shift.

    It worked really well. You could really keep that thing on plane, well below the speeds you'd usually expect it to fall off. It's been a long time but I think he said he could keep it on plane down to about 10 knots, whereas before he put the transmission in it would fall off around 15. He was a tinkerer and an interesting guy in general and had hand-built a series of race cars that were solid performers. When I knew him, he owned a transmission shop and mostly fixed cabs. But he knew automatic transmissions inside and out and I wasn't surprised when it turned out he'd put one in his boat.

    Anyway I've seen it work. It's been so long I don't remember the boat well - I THINK it was a 28 Uniflite but he had a single 454 for power and the Uniflites I have seen since then in that size were twins, so I can't swear to that. But I also didn't know boats nearly as well back then. He could well have completely re-engineered the power; he was that kind of guy. But the concept works although if I recall correctly I think he had to come up with some kind of thrust bearing solution to deal with the load the prop would have put on the transmission as it tried to push the shaft forward into the motor, because I guess automotive transmissions aren't designed for that. I guess that's normal for inboards; I don't have much experience with them. I just remember him talking about the challenge of finding the right thrust bearing.
     
  4. gonzo
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    gonzo Senior Member

    A boat will start planing at a fixed speed. There is no way a transmission ratio will make get on or off plane at different speeds.
     
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  5. missinginaction
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    missinginaction Senior Member

    I'm still waiting for an answer to Gonzo's question. What is the purpose of the project? All I can see from the posts is that the boat is 30' long and makes 650 horsepower. Is the objective speed? Efficiency? Acceleration?

    I posted a while back and I'm certainly not trying to discourage someone from developing a new idea.

    While I'm not into speed on the water for myself, if I were and had money to burn I'd repurpose a turbine get myself a big old pump and build a real jet boat. For me those are the people with the real go fast rigs but I'm too old for that. And not rich enough.

    But the original question is still unanswered. What are you trying to do?

    MIA
     
  6. cracked_ribs
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    cracked_ribs Junior Member

    Well, I was never on it before the conversion, but it would plane very slow in the slop and not get knocked off, and I remember him saying that previously it would drop off plane like a typical large powerboat. I assumed it was because he was able to turn a larger prop with the lower gear, and have more bite on the water and so was less subject to being knocked off plane by a wave.

    Lots of guys find that a duo prop will hold a slower plane than a single, I assume for the same reason.
     
  7. MRover
    Joined: May 2020
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    MRover Junior Member

    I just want a stronger transmission than what I have been using BW72C . My goal was to find a way to shorten the unit to better fit without using a V-drive. What it seems is that I need to be schooled on props, multi-speed transmissions with no actual input to my first and only query. How to connect the input shaft to the pump drive so I can eliminate the torque converter and shorten the bellhousing?
     
  8. gonzo
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    gonzo Senior Member

    A flex plate and a splined shaft would connect them.
     
  9. jehardiman
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    jehardiman Senior Member

    So you want to run a salt car set-up. (Not sure how this would work on a boat, salt cars are pushed to get rotation so you don't snap the gear teeth off. Perhaps only shifting at idle and the lack of prop bite will allow the unit to survive...<shrug> never used one.) Yes, there is a "spider" made that seals the torque converter fluid path but still drives the front pump. You will need to replumb the pump inlet and outlet with your selected activate/bypass pattern. I have no sources, but apparently it is a thing (for those who never learned to use a clutch).
     
  10. gonzo
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    gonzo Senior Member

    Boats plane when they reach a determined speed. Gear ratios don't make any difference. Adding rake to a propeller will, because they have a vertical component on the thrust.
     
  11. MRover
    Joined: May 2020
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    MRover Junior Member

    Yes, I am using a TCI Circle track pump drive now, My goal is to shorten the input shaft and the pump drive so it can fit in a shorter bell housing.
     
  12. brendan gardam
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    brendan gardam Senior Member

    completely wrong. i have seen it firsthand. autos work in boats.
     
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  13. Barry
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    Barry Senior Member

    I had heard that Merc was building a 600 hp motor with a transmission and here is the link. Note that they state the purpose were two fold, faster acceleration and shifting down at CRUISE speed to save fuel.

    In order for this to work, the engine would be able to produce enough horsepower at the lower engine rpm and operate at a better fuel efficient rpm than a fixed gear ratio.

    Two speed ahead: ZF Marine launches industry-first 2-speed transmission for outboards https://www.sail-world.com/news/236240/ZF-Marine-launches-2-speed-transmission-outboards
     
  14. missinginaction
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    missinginaction Senior Member

    Maybe it would be worthwhile having a conversation with these people. It might beat trying to engineer your own rig. A little pricey? Yep, but for people with money maybe it's an option. Manufacturer says it's rated for 2,000 horsepower. I doubt you'd break it with 650. I still think that for 99.9% of applications this whole 2 speed thing is impractical but for a tiny segment of the population maybe it's the only choice.

    COA-281110 - "XTREME MARINE TECHNOLOGY 2 SPEED" POWERSHIFT XMT, 1.375 26 SPLINE SUPER ALLOY INPUT SHAFT, 1.375 32 SPLINE OUTPUT SHAFT, 1480 SERIES COMPA... http://www.coanracing.com/coa-281110-xtreme-marine-technology-2-speed.html

    Then again, if I were interested in going really, really fast I still think a turbine/pump is more practical and maybe even more economical. It would certainly get you more looks at the boat launch. The video below would give you an idea of the power produced and more importantly the durability of these rigs. Canadians, and I guess New Zealanders are IMO the masters of "out of the box" thinking. If we get stuck down here in the states we call Sea Tow. These guys didn't have that option.......amazing. You can fast forward to the 15 minute mark to save yourself some time.



    MIA
     
    Last edited: May 5, 2021 at 8:58 AM

  15. MRover
    Joined: May 2020
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    MRover Junior Member

    I looked at the Coan racing unit and @ 12k I'll take a hard pass.
    I too would love to have a GE T700 turbine with just a simple crashbox FNR gear.

    That's one heck of a pilot!!
     
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