Bking:
But one question how the hell do you have “ports” at both ends of the cylinder?A diesel that does not need compression? You will be telling me next you dont need fuel.
Ah the good old days!
You appear to have missed the reference to it being an “opposed piston” design. Such engines have two pistons in each cylinder, acting from opposite ends. As such there is no cylinder head (the combustion chamber is formed by the two opposing piston crowns). The Commer had “Uniflow” ports, which meant that the inlet ports were towards one end of the cylinder, and the exhaust ports at the other. Both sets of ports are only open when the pistons are near their respective Bottom Dead Centres, at which point the forced airflow from the blower purges the spent exhaust gases and replaces it with a nice charge of fresh air.
The Napier “Deltic” used in marine and rail applications had a similar piston and port arrangement.
You need to differentiate the ported horizontally opposed piston type from the Detroit type which used ports and valves.
As for two stroke runaways of any type.The fact is Detroit two strokes were fitted with an emergency shutdown which cut off the inlet and although,like 4 strokes,I never personally saw any even come close to running away it was something which was common knowledge over the years amongst their users.Supposedly mostly being caused by fuel supply and metering problems.As for modern 4 stroke diesels running away for whatever reason the evidence seems to be out there.
How is this debate still rumbling on? Anyone who has been around Diesel engines for any length of time in any sort of engineering capacity knows its possible for a diesel to run on its own oil. Ive only been in the trade 13 years and I’ve witnessed it twice. Once an intercooler which hadn’t been drained after turbo failure and once with an overfilled sump. Both very much running on oil an very much ungoverned. One bent a rod and obliterated a liner and the other threw a rod. Made quite a mess!
AF1:
How is this debate still rumbling on? Anyone who has been around Diesel engines for any length of time in any sort of engineering capacity knows its possible for a diesel to run on its own oil. Ive only been in the trade 13 years and I’ve witnessed it twice. Once an intercooler which hadn’t been drained after turbo failure and once with an overfilled sump. Both very much running on oil an very much ungoverned. One bent a rod and obliterated a liner and the other threw a rod. Made quite a mess!
Ask yourself why?How can an engine run without “injected fuel” (CI engine)
Even 60/40 natural gas engines need the diesel under at least a 1000 bar to initiate ignition or they do not run
Oil will not burn unless it is injected at high pressure.You cannot ■■■■ it in through an induction manifold and it will spontaniously bloody ignite.
Why bother with injection if it just burns by leeching into cylinders.
You need a “point of injection” to make diesel explode (diesel knock) or a source of ignition as in petrols a spark plug.
And how the hell does oil from an overfilled sump get pressurised to at least 300 bar(old crap engines) to get into a combustion chamber?
Sorry boys you are talking tripe
Bking:
Ask yourself why?How can an engine run without “injected fuel” (CI engine)
Even 60/40 natural gas engines need the diesel under at least a 1000 bar to initiate ignition or they do not run
Oil will not burn unless it is injected at high pressure.You cannot ■■■■ it in through an induction manifold and it will spontaniously bloody ignite.
Why bother with injection if it just burns by leeching into cylinders.
You need a “point of injection” to make diesel explode (diesel knock) or a source of ignition as in petrols a spark plug.
And how the hell does oil from an overfilled sump get pressurised to at least 300 bar(old crap engines) to get into a combustion chamber?
Sorry boys you are talking tripe
Never heard of ‘coking’ then?
Never mind, it probably doesn’t happen now, what with all those cylinder and engine cleaning agents used these days.
The reason for injectors is not to provide a "point of injection’ in the way you seem to infer. It’s to inject the fuel into the cylinder at the optimum point BTDC for fuel burn effeciency.
You can quite happily use a carb for diesel, however it burns very inefficiently because it burns whenever it feels like it rather than exploding at the optimum point. Therefore we use injectors to inject all the fuel into a cylinder at virtually the same point BTDC as a spark plug would fire in a petrol engine. Diesel doesn’t burn AS it’s injected, it’s given and takes a fraction of a second to mist and mix with the compressed air before it reaches a high enough temprature to burn. It explodes due to being misted, enclosed, compressed and mixed with just the right amount of air.
One consideration in the design of a diesel engine (and probably in injected petrol engines) is the ‘swirl’. Probably in the induction stroke but definitely in the compression stroke, the piston is designed to cause the air to swirl inside the cylinder so that, as it’s diesel charge is injected, it gets spread throughout the combustion chamber for a fast even burn that fraction of a second later.
AF1:
How is this debate still rumbling on? Anyone who has been around Diesel engines for any length of time in any sort of engineering capacity knows its possible for a diesel to run on its own oil. Ive only been in the trade 13 years and I’ve witnessed it twice. Once an intercooler which hadn’t been drained after turbo failure and once with an overfilled sump. Both very much running on oil an very much ungoverned. One bent a rod and obliterated a liner and the other threw a rod. Made quite a mess!
Ask yourself why?How can an engine run without “injected fuel” (CI engine)
Even 60/40 natural gas engines need the diesel under at least a 1000 bar to initiate ignition or they do not run
Oil will not burn unless it is injected at high pressure.You cannot ■■■■ it in through an induction manifold and it will spontaniously bloody ignite.
Why bother with injection if it just burns by leeching into cylinders.
You need a “point of injection” to make diesel explode (diesel knock) or a source of ignition as in petrols a spark plug.
And how the hell does oil from an overfilled sump get pressurised to at least 300 bar(old crap engines) to get into a combustion chamber?
Sorry boys you are talking tripe
As to the point of an overfilled engine allowing oil into the combustion chamber, the engine in question was way overfilled and the oil level was above the level of the turbo oil return drain hole causing failure of the turbo seals and the mystical runaway which you no doubt will not believe.
Bking. You seem to be a fitter in a world of mechanics.
These people know more than you.
Lanz bulldog did it for me. I know a bloke who has one and I’ve seen it run in reverse.
Perhaps this is a case of I went to college for 5 minutes compared to bloke who did real apprenticeships.
I’ve seen a pug turbo exactly as describes. The bears fail. The turbo ruins itself. It’s very common in the 1.6 HDI which is why Peugeot have discontinued the rubbish. The term used is swallowed it’s turbo.
Of course an engine won’t run on engine oil… if you try hosing it into the cylinders a pint at a time - just like a cold engine won’t start if the injectors are doing the same. But we are not considering trying to start the thing; it is already hot and running, and probably quite quickly too. The clues are within the following, which should mean something:
I was once an apprenticeship served truck mechanic back in the late 80’s / early 90’s. In case anyones wondering, I gave it up because the money is crap. Before that, I worked on agricultural stuff for a couple of years after I left school.
Fact of the matter is, any diesel will run off its own oil because of the huge compression pressure as apposed to a petrol (spark ignition) engine. The compression on the diesel is high enough to ignite the oil because the high compression gives a massive temperature rise of the inlet air as the piston squeezes it so igniting the fuel, weather that be engine oil, gear oli or whatever, that’s how a diesel works.
On older tractors, we had to be real careful when when re filling / over filling oil bath air filters for this reason!
The following youtube clip shows an American 4000 HP diesel locomotive running away on its own oil.
Its a 4 stroke V16 of about 12 litre PER CYLINDER and built by Genral Electric.
This particular type of machine does it fairly regular after a turbo failure as it just pumps its own lube oil through the knackered turbo into the inlet manifold. Ive a good friend in the US who’s a locomotive mechanic who gave me the details.
Good simple explanation of how a Detroit 2 stroke diesel works here. From that its clear it could run with the crank turning either clockwise or anti clock.
Pity this doesn’t go as well as it stops Daniel, it must be time to get the old girl out again, we must be ready for another Cannonball Run again, are you going ring Mr. Mellor or shall I
1970commer:
Pity this doesn’t go as well as it stops Daniel, it must be time to get the old girl out again, we must be ready for another Cannonball Run again, are you going ring Mr. Mellor or shall I
Leave it where it is until the sun shines Dan! Remember that Gardner engined Sed Ak 400 I had at Tilcon Rob, that ran backwards when I stopped loaded going up Buxton Hill and needed crawler to set off, I suddenly had no RPM and a cab full of smoke from the aircleaner!
The TK Bedford I mentioned on page one somehow still managed to rev it’s nuts off with the injector pipes smashed off, must have been running solely on fresh air and not sump oil thrown up by the crank webs?
1970commer: And as for a2 stroke diesel running backwards oh dear we are in fantasy land now.We are talking diesel 2 strokes here not some bloody BSA Bantam, So the blower ■■■■■ the air out the cylinder as the piston bottoms,the exhaust valve opens to let in a bit of air, the valve shuts,the piston rises,injection,the piston drops and the blower ■■■■■ out the exhaust and repeat.
For the benefit of Bking with regard to both your quotes from above.
A little lesson in 2 stroke diesel engines. To the un-informed, yes, they probably are from fantasy land but in reality they are a unique piece of engineering, I refer to the Commer 2 stroke which is a 3 cylinder opposed piston horizontal engine, no valves to open and let in a bit of air, no valves to close either. Air is forced in through ports in the cylinder wall by a rootes blower as these 2 stroke diesel engines could not draw their own air in, diesel is then injected in by a centrally mounted injector in each cylinder, after combustion exhaust gases are exhausted via exhaust ports at the opposite end of the cylinder to the inlet ports, in service it was quite a common occurrence for these engines to start in reverse, if they stalled on an uphill incline then rocked backwards the engine would start in reverse. These engines were fitted with an anticlockwise CAV starter, sometimes it had been known for a fitter who was not paying attention to fit a clockwise one (as they looked the same as one fitted to a Perkins 354 or similar engine) this would also cause the engine to run in reverse. For a full explanation of the workings of this engine with diagrams see oldengine.org or google Rootes TS3
No thanks I have managed to drag myself into the 21st century.But one question how the hell do you have “ports” at both ends of the cylinder?A diesel that does not need compression? You will be telling me next you dont need fuel.
Ah the good old days!
Oh dear Bking, you do seem a little out of your depth on this one now, as someone else pointed out you seem to be a fitter in a world of mechanics, I gave you the information to go away and research these unique engines but you chose to throw it back in my face, well to show you how you can have an engine that cannot create its own compression and has a cylinder with ports at each end I now post you some pictures, I do hope this makes the matter simple enough for even you to understand, if it is still beyond your realms of comprehension please feel free to arrange a visit to my premises where you would have the choice of these engines to have a look at, either the one which runs in my lorry (which Dan Punchard has kindly put a picture of on this thread) or my spare engine. I would gladly take a sideplate off this as it stands on the floor so you could see the engines’ workings, it gives me great pleasure to show people like yourself how these engines work and I can feel safe in the knowledge that if you still spout the same clap trap as you have been doing on this thread then at least I tried to help. I await your informed reply & possible apology
