2 Stroke Diesels?

[No1_Moose]

I am probably missing something obvious here!
Why are 2 stroke diesels not more common in leisure boats? Surely getting more power from a smaller engine is a great advantage. They can run on much poorer quality fuel (eg HFO) so they could easily take sunflower oil,,,no? This could be an issue in a couple of years/forums/images/icons/laugh.gif

<hr width=100% size=1>I fully understand if you wish to ignore me!!!

 

[[2068]]

http://www.yachtsurvey.com/comparing_diesel_types.htm
or
http://www.dieselnet.com/news/9807ddc.html
or
http://www.marinediesels.co.uk/
(click on "the basics")

(on 2-stroke trunk) - "lubricating oil splashed up from the crankcase to lubricate the liner can find its way into the scavenge space, causing fouling and a risk of fire..."

(or crosshead) - fine for very long stroke, very slow, very big, commercial engines. Not so useful (bit heavy) for the average Sealine...

Detroit Diesel used to make 2 stroke diesels at the larger end of the scale but stopped. Think large american truck or bus. Imagine the noise and the smoke, and the physical size / weight of the thing...

dv.

 

[oldgit]

A good place to look would be <A target="_blank" HREF=http://www.yachtsurvey.com/GasNdiesel.htm> HERE </A>.Loads of interesting info on diesel and seem to remember bit of detail as to avantages of two stoke oil burners.Deals mainly with big lazy American lumps but very interesting never the less.Warns of trying to squeeze to much power out of engine blocks.
Mr Volvo fer instance????/forums/images/icons/laugh.gif and then owners of super dooper turbo/supercharged under powered glassfibre bricks wonder why the donkeys self destruct after 500 hrs at WOT.
Site also sticks the knife into Mercruiser exhaust riser design problems,big time./forums/images/icons/laugh.gif

<hr width=100% size=1>Stupid place to leave an island anyway......

 

[mirabriani]

I recall Commer lorries (in the days of Rootes Bros) used to have two stroke diesels. They might have been American sourced. I recall they were not very economic. Also the drivers used to use the choke for more power on hills= made a lot of thick black smoke. Probably these disadvantages killed them off.
Regards Briani

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[Admiral]

Briani,
I think that you will find that diesels don`t have chokes, at least all the ones that I have come across and worked on haven`t.
We also used smaller two stroke diesels in the Grey Funnel Line with very little problems as I recall.

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[Bejasus]

I've got 16 of them on board here. Big(14 x V-16-92 2 x V-16-92T), ugly, smelly, smoky & thirsty. Big power output when on song, and sound glorious at full chat.(if you like that sort of thing)

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[[2068]]

mr pascoe gives Yanmaa a harder time than V*lvomort, mainly cos of some aluminium parts that were used in earlier engines.

and a quote from Karl on the BoatDiesel forum (talking about KAD32's)...

"Given that the engine(s) are applied correctly (Installed in a 50' tug and operated @ full throttle 95% of the time is incorrectly applied), propped correctly (WOT 3850 - 3950), operated correctly (max extended cruise rpm 10% below WOT) and maintained as per the owners manual I submit that a realistic average time between overhauls is between 4,000 - 6,000 hrs."


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[Mike21]

Did read thru, did notice mentioned exceeding manufacturers specs, which suggests lot of engines he's talking about have been modified.
In theory since volvo design and manufacture their own engines this shouldn't be the case with them/forums/images/icons/crazy.gif

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[Peppermint]

Re:Got to be noise and economy

I used to drive a Commer lorry with twostroke diesel engine.

It was thirsty to petrol lorry levels, noisy enough to make Anadin shareholders happy bunnies and by Bedford or Ford diesel standards it was unreliable. I suspect that to get one to work well it needs to be a bigun.

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[Swampyhotdog]

Re:Got to be noise and economy

Which is the reason they were refered to as cathedral engines in the olden days (when my ch. eng. was a lad)

Stu

<hr width=100% size=1>As with most posts here - my personal opinion - take it or leave it.
Stu

 

[Geoffs]

Can't help feeling that there is scope for developing medium speed two stroke diesels, if someone put their mind to it. Just compare the 2 stroke outboard of 20 years ago to the modern 2 stroke DI engine.

I worked on a large 2 stroke cross head diesel, 420mm bore, 1000hp per cylinder, and that was a baby. This thing, state of the art B & W engine, would achieve 50% thermal effiency. Not bad, when a good power station can barely reach 40%.

<hr width=100% size=1>Old Chinese proverb 'Man who sail boat into rice field, soon get into paddy'

 

[oldgit]

Re:Tug eh.KAD 32 eh.

That will be the first and only tug that I have ever worked on that could go onto the plane,pulling a 1000 tons of barge as well no doubt.That Kad 32 would last oooh about 5 minutes at best trying to pull anything heavier than a rice pudding skin,unless of course they were using a 10.1 gearbox./forums/images/icons/laugh.gif

<hr width=100% size=1>Stupid place to leave an island anyway......

 

[kimhollamby]

Noisy and inefficient.

Quite a few boats in the late 1980s and early 1990s got fitted with Detroit 550 two-strokes because you couldn't (at the time) beat them for physical size and power-to-weight ratio. But I also remember a few owners becoming seriously unstuck over the fuel consumption issue -- range was quite a bit less with these engines than owners expected.

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[[2068]]

Re:Tug eh.KAD 32 eh.

agree, high power, small displacement diesels (like KAD32, KAD300) don't work at all well continuously pushing high loads in semi displacement or displacement craft, but that's not wot they're designed for. Anyway, you can talk, you have 12 V*lvomort cylinders from the dark ages...

dv.

 

[Dave_Snelson]

I read both those articles from DH Pascoe and found them interesting. Why interesting? Because they confirmed an age old axiom about engines that will never go away. Remember the Harley Davidson advert??...

"Ya caint beat cubes"


<hr width=100% size=1>Madoc Yacht Club
<A target="_blank" HREF=http://www.madocyachtclub.co.uk>http://www.madocyachtclub.co.uk</A>

 

[Moose]

Why in the world do you want to know about 2 stroke diesels? Hurry up and get that garage floor painted!

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[KevB]

I think most of the old sunseeker camargue 46's had detroit 2 stroke diesels. Very thirsty.

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[Divemaster1]

Re: 2 Stroke Diesels & a confession

Well ..... the V6 & V8's of Detroit, of which the 550's Kim mentiones were of the higher spec ones and typically did consume approximately 25% more fuel per HP than the straight six's, which were restricted to the 150 - 485 HP range. The 6.9L 71 models are probably one of the most successful 2-stroke diesel of the range, being delivered up to 485 HP for leisure use. Problem with these engines is how to get rid of the heat from the combustion .... leading to very sensitive cooling systems etc., and subsequent problems with frequent re-works on the engines where more than 400 HP were taken out. The 2-stroke diesels have a distinct sound thugh....

Now for the confession ..... It appears that I have just bought a Italian boat from the mid 80's, with two of these 2-stroke V71 TA straight six's onboard.... Big lumps at 1.4T each and 325 HP, which means that you need a decent engine space onboard to fit them in...... The fuel consumption graph on these engines does not appear to differ very much from the equivialent 4-stroke of that era. I do know that these engines in particular are very well kept and should not give me any problems for quite some time if run properly, and if so re-conditioned parts are readily available throughout the world. Engines sound great and do run very smoothly from idle to top.... WOT @ 2300, and cruise between 1800 - 2100, which gives a very smooth run indeed, with vess vibration onboard than on Sealines Schoolboat F43, with 480 V..'s. Apparently the 2-strokes does not like to be running slow, but do "like" to be worked...

<hr width=100% size=1>Alf

 

[oldgit]

Please Sir Please Sir.......

Please Sir,dvinell from the lower third is saying horrid things about my V.l.os.Tell him to stop Sir................/forums/images/icons/laugh.gif

<hr width=100% size=1>Stupid place to leave an island anyway......