Narrowboat Engine

Discussion in 'DIY Marinizing' started by timswait, Jul 4, 2008.

  1. murdomack
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    murdomack New Member

  2. timswait
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    timswait Junior Member

    So if I use the car's exhaust manifold and air cool it then I can soft mount the engine and use the stainless bellows to take up the vibration? If I use the water jacketed exhaust mani then I still can't use rubber hose, so I still have to use the stainless steel bellows? So what's the advantage in the water jacketed mani?
    What parts would I need to run a wet exhaust? I think I'd still use the keel tank for cooling the engine. Can I use the Bowman water jacketed mani to inject the water? I have drawings for it from Lancing and it shows a sea water inlet, so is this where water is injected if it's being used as a wet sytem? What other parts do I need, just a pump to pick up raw water and a pipe to connect it to the Bowman? Is the pump engine driven or electric? Do I still need a silencer (muffler for the Americans ;) ) if I have a wet exhaust?
    Thank you for your helpful answers so far.
     
  3. murdomack
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    murdomack New Member

    There are good articles attached by Pericles, Post #3 on an adjacent thread, that you can study and make your own decisions. The second link is the one about the dry exhaust and it makes a comparison with a wet system.

    http://www.boatdesign.net/forums/diy-marinizing/rebuilding-marinizing-tractor-trailer-22184.html

    Here is a site selling flex hose for dry exhaust

    http://www.chandleryworld.co.uk/acatalog/DryFlexibleHose.html

    Here is another thread on the benefit of the water cooled manifold in a dry exhaust. In one of the later posts Fast Fred is saying that a bigger keel cooler will keep this manifold cooled.

    http://www.boatdesign.net/forums/diy-marinizing/why-install-wet-manifold-6701.html
     
  4. murdomack
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    murdomack New Member

    Looking again at the Bowman site, page 26/26 of the pdf, this unit is available without the heat exchanger tube bundle for keel cooling systems. It is called VW150-3490KC. Might be cheaper?
     
  5. CDK
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    CDK retired engineer

    Without the tube bundle it will be much cheaper, that's an expensive part. With keel cooling you can include the water jacket in the cooling circuit's return and you do not need a separate pump.
    You can save some more money by ordering the part from mesamarine.com. You pay them, then Bowman sends the part directly to you. I saved over 30% that way (no VAT and the US price is lower than in the UK).

    With the water cooled manifold you avoid the problem of an 600 degrees C. piece of iron in your engine bay, that would require you to move the air around the engine as if it were in a car. 50 mph wind takes a very large fan!
    The exhaust pipe you can insulate, but the manifold will crack if you do that.

    Of course you want to use a silencer. I tested the engines without one, with just a piece of pipe: the sound resembles a Sherman tank. In a wet system the injected water and the rubber hoses absorb most of the exhaust noise, the last bit is removed by a small steel or plastic jar in the lowest part of the path. The VW Golf has 2 silencers that do a very good job. If you have the space for them I recommend you use these.
     
  6. timswait
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    timswait Junior Member

    The project's progressing fairly well. The engine's out the car and separated from the gearbox. Unfortunately I don't have any good photos, but here's one of the engine.
    I've got hold of a Hurth ZF15M gearbox to use with it. I've used the bell-housing from the car gearbox and have machined an adaptor plate to go between the bell-housing and the gearbox, so that all now bolts together and the gearbox input shaft is perfectly centred on the crankshaft of the engine.
    The problem now is how to connect the gearbox shaft to the flywheel. I was hoping to find somewhere I could buy a tube with the correct spline to match the gearbox and then to machine the other end to something I could bolt to the flywheel. How do people normally connect the shaft from a marine gearbox to the crankshaft of the engine? I do want to keep the original flywheel so I can use the starter motor as it is.
     

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  7. CDK
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    CDK retired engineer

    You need something called a damper plate. It is basically a clutch plate without the friction material and if you are lucky you can buy one with a hole pattern that fits the flywheel. For my VW diesel conversion a bought plates with just the proper diameter but the wrong number of holes so I drilled new ones in the flywheel.
    Lancing Marine has them in stock, so do other Hurth retailers.
     
  8. timswait
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    timswait Junior Member

    Why is it that car engines are always mounted on 3 points and boat engines on 4? As I see it the loads the engine mounts have to support are the same or lower in a boat than a car. There's the torque loads from the engine (same in car or boat, maybe slightly lower in the boat as there's no sudden jerk as you take up the clutch), the static weight of the engine (same in car or boat) and any dynamic loads from cornering, going over bumps, rolling around at sea (likely to be much lower in the boat). So what is it about putting it in a boat that requires the extra mount?
    There's nothing on the front left corner of my engine substantial enough to bolt a mount to. The water pump, alternators and injection pump are all bolted to the block here and I can't really see any way to make a mount work. So I'm planning on mounting it how it would have been in the car, with one mount on the front right of the block, one on the rear left and one on the rear right of the gearbox. Is there any reason this won't work?
    I've attached a photo of the engine bolted up to the gearbox (I haven't got a damper plate yet so the shafts aren't connected yet). The plate on the back of the box is what I'll make the gearbox mount out of. The other photo shows the progress of the boat it's going into.
     

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  9. CDK
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    CDK retired engineer

    All the Mercruisers, Volvo's, OMC's and Yamaha stern drives with inline engines have 3-point support, two on the transom plate and a central one at the front of the engine. So a substantial part of all marine engines are mounted like car engines. Very awkward because there is no easy way to changing a belt, but aligning the engine is simpler than with 4 legs.

    But you're right, engines with gearbox and prop shaft stand on 4 legs.
    In my post: http://www.boatdesign.net/forums/diy-marinizing/marinizing-vw-turbodiesel-engines-19118.html there are some photographs of the supports I made. There usually are several unused holes in the engine block; if not, you can use the holes where the alternator or water pump brackets are attached by taking a somewhat longer bolt.
     
  10. timswait
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    timswait Junior Member

    I have been giving your posts on the TDi's a good read. The area around the water pump looks quite different on my engine, The holes you've used seem to have things covering them. Are the TDi's mounted vertically or canted at 15 degrees? The SDi is intended to be over at 15 degrees, and I'm planning on putting it in the boat like that. Annoyingly I didn't think of that when machining the gearbox adaptor plate, so the gearbox is now also going to be at 15 degrees. Still it says in the spec that it can be used up to 30 degrees, and the boat's no really going to be rolling around much so it should be OK.
     
  11. CDK
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    CDK retired engineer

    Straight up or slanted, I do not see any problems. Mine are standing vertical because the expansion tank on top of the manifold is so high that the filler cap almost touches the floor board. At 15 degrees slant I would need a hole in the floor or raise it an inch.

    The oil pump is located between cyl. 3 and 4, but there is a suction tube pointed towards the front of the engine. Since the angle of the prop shaft and engine is 8 degrees down, I must overfill the engines a bit to make sure that the pump always sucks oil. Should it ever be necessary in future to lift the engines, I will remove the oil pans and cut off the tubes.
     
  12. Chris Bretter
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    Chris Bretter Zaphod

    The thai boats are the way to go there are some pictures on this site
     
  13. timswait
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    timswait Junior Member

    What do I do with the EGR system? Can I just take the valve off the inlet mani and blank the hole off? There's nothing on the Bowman exhaust mani to connect it to.
     
  14. CDK
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    CDK retired engineer

    The EGR system is a passenger car requirement with slightly negative effects on the engine performance. One of my engines already came with a steel plate under the valve, so the EGR was only optically there to satisfy an inspection.
    You can discard the valve, the hose, the wiring and the controller (if one was there).
     

  15. timswait
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    timswait Junior Member

    My engine has a vacuum operated throttle butterfly on the intake plenum. As I understand it diesel engines don't ususally have any throttling on the air entering the engine, so I'm guessing this is also something to do with the EGR system. Should I just lock this butterfly fully open?
     
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