Auto Diesel (Yeah, again, but...)

Discussion in 'Propulsion' started by Filmdaddy, Jul 21, 2005.

  1. SAE140

    SAE140 Guest

    Well, you *can* resent my comments about rip-off chandlers if you wish - I'm not sure I care very much about a single point of view on this issue, as my opinions are shared by the hundreds of people I've discussed this matter with, many of whom were under the mis-guided impression that there's no viable alternative but to cough-up hard earned money to buy only what chandlers have on offer.

    Suggest you read Brent Swain's "Heretics Guide", then take a walk around a typical chandlers. Have you bust gear at sea ? Of course you have, so have I. Stand back and take an unbiased view. Gear busts because saleability considerations are given a higher priority than 'unbreakability'. Over-built stuff simply wouldn't sell.

    You're missing several points: - these may be "amateur engine installations" inasmuch as they are installations by people who are not paid by others for performing soley this one activity, but that should not be taken to imply that these are "amateur-ish" installations in the sense that these are sloppy and unreliable.

    The most common engine on UK inland waterways ?
    BMC diesels - straight out of London taxi's. Thousands of 'em have been installed by amateurs, and are in use every day. Modified - sure - but only superficially. And these installations have to pass a European safety examination.

    You're also missing the point that I'm not talking about making a direct comparison with kosher heavyweight low-revving marine diesel engines like Saabs, Gardners and Listers, but with their modern high-revving counterparts which invariably are installed in situations where they will rust-out long before they wear-out.

    I'm also not talking about work-boats, high-speed power boats, or anything similar. Just auxillary diesel engines for displacement sailing craft.

    A rather useful example to quote is that of Nick Skeates in his steel gaff-rigged Wylo-II. Nick has a Bradford (similar to the Jowett Javelin) gas engine on board, complete with it's automotive gearbox. He's been running this amateur-installed rig for well over 20 years of *continuous cruising*. In that period of time I've seen one boat in my home port get through 3 'professionally-installed' Yanmar diesels.

    I've just bought a Ford 1.8D for £50 which should be good for another 100,00 miles or 2,000 marine hrs. It might cost a couple of hundred quid to convert, but these parts will transfer across to another £50 replacement engine when the time comes. Yes - carry a replacement on a cruising boat - cause at £50 a go, it doesn't make any sense to spend serious money repairing 'em.

    A "fully-marinised" and fully-rebuilt Ford 1.8D on the other hand was recently offered on eBay for £2,500.
    There's a 4108 (another ex-automotive engine) currently on eBay (4564899009) for £3,250 I think these kind of figures speak for themselves.

    Colin
     
  2. gonzo
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    gonzo Senior Member

    A marine engine running at rated HP or about 10% less is the equivalent to a car driving at 130 MPH. 100,000/130=769hrs. However, because of the more severe service, it will be less than that. Perhaps 500hrs at best.
     
  3. woodboat
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    woodboat Senior Member

    I think that is a safe generalization but not necessarily true. I took a chevy 307 out of a Nova that had 300,000 miles. The fire department tried to blow it up. They ran it in neutral for hours with a brick on the gas. I pulled it out, did NOT rebuild it. Stuck it in a 26 ft trojan and ran it for two years. We then pulled it and put it in a crabbing boat for two years. It still ran the same when it was parked. You generalize, gonzo about the load but a V8 chevy in a light boat will not suffer the same conditions as say the same engine in a planing 50 ft houseboat. Also a small diesel in a displacement boat will not see the same load.
     
  4. SAE140

    SAE140 Guest

    I don't know where this 10% figure comes in ......
    The diesels I'm talking are typically 50 bhp(ish) at 4,500 rpm and produce max torque at around 2,000rpm (where they produce around 25 bhp).

    2,000 rpm equates to around 50 mph on the road with a five speed box. 100,000 miles divided by 50 equates to around 2,000 hrs running time in that situation. (ok - that assumes that the vehicle is forever driven in 5th gear, and always at 50 mph ... but you get the drift)

    At 200 hrs/year (very typical auxilliary sailboat useage) that's 10 years from one engine. Sure, it might be less - I wouldn't want to get hung up on these kind of figures especially when a busted cam belt would void these claims instantly. (Moral - change the belt regularly, or use an engine with a cam-chain)

    Remember, I'm talking about plodding along for most of the time, with the occasional burst of power when things get sticky.

    To run at full rated bhp (or even 10% less) is probably something a high powered craft would be doing. In my application, the engine is *never* asked to produce more than 50% in normal service. That's good on fuel (an important consideration as we poor sods have to pay the equivalent of $8 a gallon), and kind on machinery.

    Best regards

    Colin
     
  5. tom kane
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    tom kane Senior Member

    When you take a close look at an engine running in a boat,it has an easy life compared to one running in a motorcar.There is no over reving,if set up well,no back-lash from motor braking.If set up and used sensibly a boat motor instalation can be like running a motor in a test bed or dyno,every thing under control.The enviroment can be controlled with good dry exhaust (to keep exhaust pulses pushing sea water back against the valve seats).Closed water cooling,even with the auto radiator,plus heat exchanger for extra cooling.
     
  6. Frosty

    Frosty Previous Member

    Filmdaddy i say go for it and enjoy yourself. When I was a 19 year old kid, auto engines was all I could afford -- we used to use Ford 1600 cc I made everything. Firstly I had no gearbox and drove from the single key of the front pully with a pinch bolt to stop the adaptor from coming off ( why would it come off --no reverse) the cooling was as in the car, by blisters that were riveted onto the inside of the alluminium hull, these were sealed and you could put any addative if you wanted. The sump had an oil cooler inside to cool the oil made from 1/2 inch copper plumbing pipe made from 90 degree elbows. this was fed by a pick up on the hull so as the boat moved( when the engine ran) water would circulate, and eject from the side of the boat as a tell tale. Not a problem and very efficient. The exhaust manifold was made by injection of sea water into each cylinders out pipe, it wasn't a cast manifold but a scrapper off a 1600E these had mild steel manifolds that were called bannanas, they looked just like a bunch of bannanas, easy to weld in or braze 1/4 inch pipes after the highest part obviously. These pipes were fed but a Jabsco 12 v pump. Carb was untouched even though there was quite an angle to the shaft and motor. Starter and Dynamo were standard car stuff along with distributor and everything else. The engine mountings were mountings from some car gearbox and the mounting plate was 1/4 plate bolted to the bell housing bolts The fronts were on the car original mounts. We skied on the river all summer at almost WOT the whole job engine as well cost about 8o quid. The thing is I copied the best I could from the original manufacturer Albattros of Great Yarmouth Uk. Now many many years later I have just bought 2 Yanmar 6 LP-- 250 HP 13000 pounds each.-- On the back of the block by the raw water pump is stamped Toyota and after serious investigation it IS a toyota engine from the Toyota land cruiser 1 HD The workshop manual is also Toyota as it mentions taking the viscous clutch off the water pump Oops, I think that one slipped through. Go for it Filmdaddy go.
     
  7. SAE140

    SAE140 Guest

    As I see it, there are 2 possible long-term negatives: the first is the risk of continuous over-cooling, as the sea presents a huge heat-sink, even when using fresh-water cooling. However, this is easily guarded against with a reliable thermostat and some kind of low temperature warning system.
    The second is the process of bore-glazing. Provided the engine isn't left on tick-over for countless hours on end this shouldn't become a problem, but if it does develop it'll cause an increase in oil consumption - something to be aware of.

    My view is that purpose-made marine engines (Sabb, Lister etc) are superb pieces of engineering, and are vastly superior to their automotive equivalent - but when capital cost is taken into account, together with the annual operating hours typical of leisure craft, plus the "rust-out before wear-out" factor so commonly seen in those leisure boats which are condemned to spend 95% of their time at moorings, then there is indeed an arguable case for the use of automotive engines in boats.

    What I find frustrating is to so often hear people say that this isn't a good proposition - as if it is some pie-in-the-sky idea on the drawing-board waiting to happen. Ex-automotive engines have been used in boats in the UK (and I'm sure elsewhere in Europe) for over 50 years, and which no doubt has it's roots in the economically deprived couple of decades following the second world war. Those from countries who didn't experience the same kind of deprivation, and the ingenuity which invariably results because of it, appear to adopt a completely different approach : that of "a purpose-made piece of equipment already exists - so fit it".

    To those of us from other countries and with different backgrounds this seems an intolerant and somewhat blinkered approach, as we have learned from our experiences to be frugal and inventive.

    Regards

    Colin

    (written before reading Jack Frost's post - Thailand sounds good !)
     
  8. tom kane
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    tom kane Senior Member

    Auto Diesel (Yeah,again,but...)

    A good reliable truck motor set up in the stern of a boat gives easier venting of engine compartment.The radiator acts as a good reliable supply of cooling water with little chance of overheating,and the heat exchanger with a good capacity ensures the water is cooled.parts and servicing become automotive cost effective and familiar to most mechenics.
     

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  9. gonzo
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    gonzo Senior Member

    I never denied any engine can be made to work in a boat. My argument is about economics. At least in the US, used marine engines are plentiful and fairly inexpensive. An old boat with a rebuildable engine can be had for less than U$1000. That includes transmission or outdrive and everything else you can salvage. I don't see how you can get an automotive engine, even for free, and make it work cheaper.
     
  10. PowerTech
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    PowerTech Senior Member

    I know it can be done also.It is just ugly as hell.I am a marine mechanic and i hate to see all of that crap.I like simplicity not a bunch of adaptions and rusty crap.When i work on you tinkerers boats you seem not to understant quality and never want to do anything the right way.Cheap know it all's.Wierdo stuff if you ask me.
     
  11. tom kane
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    tom kane Senior Member

    If you have a boat motor set up like a motor car,it is easy to just touch the start button any time to keep it in order,on the water or on the land.Maintenance is simple and can be done by anyone that can run an auto.many of the top US power boat drivers/writers/Naval Designers say that a big percentage of boat motor installations in small power and sail boats are auto type motors.World wide the majority of boat motor installations would be DIY and these would probably well out number the factory built marine units,just in the Asian countries alone.It would be nice to think that a factory produced product would be just the best for everybody but it does not work out that way.
     
  12. gonzo
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    gonzo Senior Member

    Tom Kane:Actually it does. Automotive engines are factory produced products. If you were to get a bund of iron ore and make your own stuff, including design, then it would be not a "factory produced product". It makes no sense that "If you have a boat motor set up like a motor car,it is easy to just touch the start button any time to keep it in order,on the water or on the land.Maintenance is simple and can be done by anyone that can run an auto". If they are the same, as you claim, then maintenance should be the same too.

    There seem to be many emotional posts in this thread. None of them explain the process to get to the product they claim is better. Neither do they post a breakdown of labor and parts. I have donwe so in other threads, and it always comes to the same: DIY is more expensive and less reliable.
     
  13. Frosty

    Frosty Previous Member

    Tom kane. Once in another thread and again in this you have mentioned sea water being pushed up against the valve seat by exhaust pulses,???? What have you seen or read.? Sea water should be no where near your valve seats. Any way although i have thouroughly enjoyed fiitting auto engines to boats i would not go to sea with one. A marine ( properly marinised ) engine is of course of far superior quality. The stuff I used to play with was for coastal rivers or inland lakes ,there was always a bunch of us. Maintenance was never ending, stuck starter dog, sticking water pumps, cracked manifolds. maintenace was every day.But was great fun.The superior materials of the marine engine should result in reliability, If you get that or not i am not sure,- it certainly results in expensive. If your not keen on evening maintenance then you will not be able to keep an auto job running. I suppose it does'nt matter if your criusing the inland water ways of the UK, if you stop you stop, no one needs to risk thier life which is not the case calling mayday 100 mile out to sea.
    Also a very important point here that has been mentioned but needs another is the boats sellability. You could very easily destroy your investment, if your one of those people who thinks a boat is an investment? I wouldnt buy some one elses cock up.I enjoy making my own.
     
  14. tom kane
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    tom kane Senior Member

    You have obviously had fun jack frost.What happens in a motor,the piston creates a low pressure in the combustion chamber as it decends.This causes a negative pressure wave(a wave below atmospheric pressure) which races along the intake port and manifold runner.When it reaches the end of the runner,it is reflected back towards the engine,but this time as a positive wave.This returning wave has the potential to ram more air into the combustion chamber.That is on the induction side,on the exhaust side similar waves created by the opening and shutting valves creates waves that carry pulses back and forth which carry moisture back to the valve seats and beyond (wet spark plugs from steam) depending on the cam and manifold design.Just the fact that the exhaust contains moisture is enough for moisture to percolate back into half opened valves and cylinders,rings especially when hot,the heat attracts moisture as it cools on shut down.Look at the many threads on exhaust corrosion and marine engine problems.A boat may be an investment but the many refits go down as running expenses.
     

  15. gonzo
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    gonzo Senior Member

    Tom Kane:Your explanation on the intake shows that compression waves travel in only one direction. How do you explain that in the exhaust they do the opposite? It appears that you make things up to make your point.
     
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