Getting extra torque from your boat motor.

Discussion in 'DIY Marinizing' started by tom kane, Jul 19, 2016.

  1. tom kane
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    tom kane Senior Member

    If you can get extra torque from your boat motor as well as increased safety why would you not want to do that.

    http://shareaproject.com/manageProject.php?p=9

    The vw wagon motor is well known for it`s low RPM torque and has long induction tubes to achieve that.
    Using a long induction tube to remotely fit a carb out side of the hull so there are no parts of the fuel system able to leak fuel to gather in the bilges, and also fit your fuel supply out side of the hull must be a safer system.
    This system can be applied to EFI system as well.
    You can still use Marine parts and comply with boat building regulation.
    Using ram tubes can give more than 100% volumetric efficiency so replaces expensive troublesome turbo needs.
     

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    Last edited: Jul 19, 2016
  2. kerosene
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    kerosene Senior Member

    Low end torque is not really needed in boat application.
     
  3. Skua
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    Skua Senior Member

    No one considers aircooled vdub motors torque monsters in any configuration.
     
  4. tom kane
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    tom kane Senior Member

    getting extra

    Good torque at low RPM is desirable in all internal combustion engines especially boats to get on to plane easily.
    Internal combustion engines need to develop revs to build up HP.
     
  5. tom kane
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    tom kane Senior Member

    getting extra

    Good torque at low RPM is important in any motor you wish to choose and ram tubes give motors better torque at the RPM you choose. There are few motors without ram tubes now.
    Why do you think turbo`s are fitted to motors, same effect but ram tubes are simple and effective and are free extra HP and do not put extra wear and tear like high lift cams and other devices, and less expensive and low maintenance.
     
  6. FAST FRED
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    FAST FRED Senior Member

    "Using ram tubes can give more than 100% volumetric efficiency so replaces expensive troublesome turbo needs."

    The problem is that proper induction tubes as well as a proper length exhaust work at ONE RPM .

    If you set the engine up for cruising at this specific RPM great , other wise it can be a power loss.

    The turbo will assist as long as the engine is spun fast enough and hard enough to have plenty of energy (pressure and temp) in the exhaust.

    6-9speed Transmissions allow the RPM to be kept low for fuel efficiency , after turbo boost begins.

    "Using a long induction tube to remotely fit a carb out side of the hull so there are no parts of the fuel system able to leak fuel to gather in the bilges, and also fit your fuel supply out side of the hull must be a safer system."

    Coming along side might be expensive if Webbers are used , andv an errant wave top into the intake could cost the motor.

    For reference on engines,

    The High-Speed Internal-Combustion Engine: Sir Harry R. Ricardo ...
    https://www.amazon.com/...Engine-Ricardo.../021689...
    Amazon.com, Inc.
    The High-Speed Internal-Combustion Engine [Sir Harry R. Ricardo F.R.S., J.G.G. ... Author interviews, book reviews, editors picks, and more. ... in appreciating the engineering fundamentals of piston-engine design and development. Ricardo's ...
    Harry Ricardo - Wikipedia, the free encyclopedia
    https://en.wikipedia.org/wiki/Harry_Ricardo
    Wikipedia
    Sir Henry Ralph "Harry" Ricardo (26 January 1885 – 18 May 1974) was one of the foremost ... 8 Post war period; 9 Ricardo Consulting Engineers (now Ricardo plc); 10 Books; 11 See also; 12 References; 13 External links ... Ricardo continued to design engines for small electric lighting sets; these were produced by two ...
    ‎Early life · ‎Marriage · ‎Car engines · ‎Tank engines
     
  7. gonzo
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    gonzo Senior Member

    Turbos are not for low RPM torque. They don't spool up until there is a considerable flow on the exhaust. Therefore, turbos don't operate at low RPMs. To increase low RPM torque, superchargers are the appropriate system. Ram tubes are tuned for specific, and very narrow RPM. They will not operate efficiently at a wide range like it is necessary on a normal boat. If you are building a dragster, that is a different story.
     
  8. FAST FRED
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    FAST FRED Senior Member

    "Turbos are not for low RPM torque."

    Perhaps you might inform most shipbuilders.

    HUGE turbos and normal engine operation is 88 to 105 RPM

    Most auto turbos will make positive boost at about 2000 RPM, ones built for diesel cars even lower RPM.

    2000RPM is slow for modern 6000, 7500RPM car motors.

    Useless of course for a cruising boat tho.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Tom I have quite a bit of experience with what you're calling ram tubes. Intake runner length is married to a number of things and have several good and bad things to consider about them.

    Intake runners are sized to the operational expectations, of the engine's performance environment. In most boat engines (full plane mode craft), you'll want short, straight, properly sized and shaped runners. Again, because of their typical operational environment, which is at or near WOT, much of the time. Also because of the operational envelop, long runners would cause atomization "drop out" in the fuel vapor/air cloud. This kills efficiency and intake manufactures have been addressing this issue for decades. Insuring atomization in the cloud is vital and one of the reasons, direct injection is taking over. This is because you can live with some turbulence, if it's just air, which can be reshaped and smoothed in route, but drop out is just a killer and not much can fix it, except shorter, cleaner runners.

    The ideal runner, used on the type 1 example you've shown was a direct evolution, from the early 35 HP version you've shown (which wasn't very efficient BTW) to the dual port, twin carb setup (and eventually injected). The cut away view of these show intake runners that are 1/5th as long and they drop straight into the port, without two 90 degree bends. Of course, this required a new head design (dual port), but class racers used the same approuch on the old single port heads, simply making 3" - 4" tall runners to stand directly over the port, to which a carb was bolted. These were far superior to the handlebar manifolds or the stock configuration.

    With carburetor engines, you'll get better intake efficiency with shape, texture (amazingly enough) and diameter. Flow bench testing has repeatedly proven straight, well sized and shaped runners will do more for you than runner length. The only place vapor column length can offer improvements is pre-throttle plate, not post throttle plate. With carbureted systems, the vapor cloud stacks up over the air horn, above the throttle plate. Most american car air cleaner assemblies limit this height, mostly for under hood clearance, but in race applications, where there's no underhood limitations, the air cleaner is taller, often much more so (3 - 4 times as tall). Additionally the inlet to the venturis and air horns typically have a smooth and shaped ram to permit shaping and partly pressurizing the air mass as it enters the top of the carb. If you take this one step further (many racers did), you put a velocity stack over it, which permits the vapor cloud to stand up further, straightening out the flow and making better atomization once it passes the through the carb. In fact, the stock 35 HP VW air cleaner did just this, with a 4" tall tube (old oil bath cleaner) within the air cleaner, which straighten out flow. On racing lawn mower engines, where tweaking every ounce of energy out of a 12 HP single cylinder motor is key, they'll install a length of pipe on the air horn and the air cleaner above this, again, to permit the vapor cloud to stand up over the carb and get straightened out, all the while retaining as little drop a out as practical.

    Lastly, long intake runners make starting an engine in cool or cold weather, all but impossible. Most applications with long runners required some sort of runner heating arrangement to permit cold weather starting, which in itself is a crutch for a clearly less efficient setup. Anyone that's owned one of the cross ram style of intakes from the early and mid 60's muscle cars will simply tell you, you could start them in the winter. Some would use a sleeping blanket on their engine, others wrapped the intake runners with block warmer wire. I had a 413 wedge with a cross ram and it wasn't startable in winter and though some modest improvements were seen with the cross ram setup, it was quickly abandoned in favor of straight up and down twin 4 setups, which incidentally had shorter, straight runners too.
     
  10. tom kane
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    tom kane Senior Member

    Collective thanks to all of the interesting previous posts for and against ram tubes used as I have suggested to isolate any fuel entry into the hull of a boat, with which I found no problems but only peace of mind and better performance. I must have got things just right even for a first time experiment.

    Some of the replies also provide solutions to some perceived problems.
    Like all suggestions commonsense is needed,like suggesting appendages would be used to house carbs etc., which could be damage.
    With a little experience and thought all of the perceived failings of trying to make a family boat much safer regarding the carriage and reticulation of volatile fuel can be sorted.
    Extreme lengths of ram tubes are not needed but standard lengths of existing motor set up can be used achieving the desired results of complete fuel isolation from the inside of a boat hull.
    It is all about new design and finding ways to make boats safer as safety is paramount.

    Just making large volumes of volatile fuel normally carried in boats beneath the cabin floor safe by isolating it against air (which contains Oxygen) and from the inside of the hull must be a bonus.

    The principle of the suggestion is to remove the hazards of volatile fuel by isolating it from where it can become inflammable by the design of the craft and machinery.

    Reminding boating people about the dangers of their boats naturally upsets them and they prefer to put possible improvements and such things out of sight.
    When you press that start button complete confidence in your boat is a great feeling.
     
  11. gonzo
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    gonzo Senior Member

    The only way to isolate the fuel from the inside of the boat, is to have an outboard with the fuel tank on a shelf in the stern. To isolate all the fuel systems from air (and oxygen), you need to either create a high vacuum or flood the compartment with an inert gas. Inert gasses will suffocate and kill humans. If you want to be safe from fuel explosions, get a sailboat or human powered boat.
     
  12. tom kane
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    tom kane Senior Member

    Googling around Images shows millions of motors over the years with successful long induction systems from the earliest days to the present time when most modern motors have them as standard, but not in boats, I suppose no one thought to apply them to boats.

    One thing is evident in this thread is that there are many misconceptions about how they work and how the principle can be modified.

    During the WW2 there were many countries using all manner of apparatus to keep petrol motors running because no fuels were available and even gas producers were used in New Zealand and often the induction tubes were very long even from the rear of the vehicle to the motor.
     
  13. mydauphin
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    mydauphin Senior Member

    Engine design is engine design. Torque to hp ratio has to do with size, bore and stroke ratio, compression and amount of fuel burnt. Back in the old days, a stock 350 Pontiac engine would put out more torque earlier than 350 cu in chevy. The Chevy would put out more hp. Engine design, and has someone mentioned torque curve, is critical for boat. Torque in boats is very important to a boat since a ships propellers work like a dynamometer. Of course remember boat gears have reduction gears. So propeller is match to top of curve, then figure gearing, then match the propeller to that torque curve.
    Torque is the reason diesels are great boat motors with less gearing than gas engined
     
  14. PAR
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    PAR Yacht Designer/Builder

    Isolating the intake charge is easy and a good way to gain a few HP. Simply sealing the incoming air flow to the arrestor is all that's necessary and this is now standard practice on automotive applications. This was stolen from racers that found a cooler air charge, was free HP to the engine. Cowl induction scoops were the most notable of this application, in the late 60's on some GM products, but now every car and truck, employs this simple power adder. In fact, some racers took this to extremes, by running fuel lines and incoming air charges though "cool boxes" which may have something as simple as a tray on the intake runners to hold ice or dry ice, to elaborate coil filled cans filled with ice or refrigerant. Intercoolers on turbo equipped applications, do the same thing and these have been around on diesels for many decades.

    A tube extending the arrestor above an inboard's engine box, eliminates one source of potential vapor escape, within the enclosed spaces, while also offering this colder air charge. Of course, this vapor escapes into the cockpit which may not be desirable, but a clamshell ducted to the arrestor solves this, if the boat has the room for this arrangement.

    There's a number of ways we could improve things, in regard to explosive vapor control, but most will simply meet requirements, before being willing to add to production costs, for less than justifiable (in their minds) equipment additions. One serious consideration might be the sole use of JP-7 fuel only, though it's $15+ a gallon price might be a drawback for pleasure boat use, it's about as stable a fuel as you can ask for.
     

  15. FAST FRED
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    FAST FRED Senior Member

    Looking at the huge number of gasoline boats on the water and the very modest insurance cost would have me conclude the past 100 years of gasoline fuel operation has made it pretty safe.

    "Safer" is always a worthy goal, but the fool with a smoke that is fueling can not be designed out.
     
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