With respect to the relative oil consumption of two-stroke engines, far be it for me with work experience at a major North American manufacturer of automobiles to challenge anyone referencing their work in the railroad industry . . . but . . .
The two-stroke engine in my gasoline string trimmer and in my chain saw runs a “dry” crankcase. These engine admit the carbureted fuel, a gas-oil mix, into the crankcase, where the downward stroke of the piston pressurizes it until the “scavenging ports” are uncovered when the piston reaches bottom. At that time, that gas-oil fuel misted into air is blown into the cylinder by crankcase pressure, and exhaust gas is blow out the exhaust ports that are open at the same time.
The engine burns both gas and lube oil because that is the only way to get lube oil on the engine parts – crankshaft, rod, piston. Also, unburnt gas and lube oil goes out the exhaust, and some exhaust gas stays in the cylinder because the scavenging is not perfect. I have a newer, “green” string trimmer, but after a morning of yardwork with the thing, my work clothes reek of chopped weed and raw fuel.
The two-stroke Diesel does not use the crankcase for scavenging. The EMD engines (567, 645, 710) use a Roots blower for the non-turbo engines, a turbine blower for the turbocharged engines, where that turbine blower is has a gear train and overrunning clutch arrangement to get enough scavenging at low engine speeds
The 20 cylinder can use the exact same emissions reduction strategies as the 16 cyl, i.e., split cooling, Miller Cycle, etc.
On a different note:
The EPA set their sights on what they call ‘off road vehicles’ (including locos) many, many years before the regulations actually hit the Federal Register. Look it up !!
California has been regulating on-road vehicle emissions since the 1960’s. Much of the current environment regulations had their genesis in California. Look it up !!
Both EMD & GE were aware of the aforementioned points. That is how companies whose sales measure in the billions work. THEY MANAGE RISK. The HDL and 265H were designed based on the knowledge of this risk-and a whole host of other factors.
The specific oil consumption of two-stroke-cycle diesel engines, no matter how one measures it, is greater than four-stroke cycle engine of the same config. and hp. A by-product of this is the fact that GE oil change intervals are much closer together than EMD. Why ? Because on an EMD, oil gets past the ring belt and into the combustion cycle…and into the by-products of combustion. EMD has effectively mitigated this built-in disadvantage of the 2 stroke over a number of years. But the disadvantage still exists.
It is irrelevant how the oil gets into the 2-stroke combustion process. What is relevant is that the oil is combusted and the by-products end up in the exhaust.
I spoke to a source (outside my industry) who is well plugged into the railfan grapevine. The obvious places for the Tier IV EMD have been vetted-TTC, TAG RR, etc. Wonder where they could be hiding ?
Stop right there. We are not talking about little two-stroke spark-ignition engines; an EMD two-stroke diesel is a completely different engine using a vastly different set of mechanical principles. While there are some applications for mixing an improved ‘lubricant’ in with the fuel, that’s done for better injector performance (as with Stanadyne) and not to lubricate pathetic reed valves or ensure an oily film keeps being deposited on wear surfaces in the absence of proper pressure lubrication.
This is technically true, but if you look at a proper exploded view of one of the EMD engines (see for example here, from the tugboat enthusiasts, you will see that the scavenge air passes very close to the crankcase, and any minor leaks between the cylinder liners and crankcase space will admit some vaporized lube oil – CIRCUMSTANTIALLY – to the scavenge port area. This may be magnified if there is any blowby pressurizing the crankcase space, etc.
Due to China’s incredible air pollution, there probably won’t be any trees to hug pretty soon. I think it’s too bad China cares more about expanding it’s industries than it does protecting it’s people.
[8D]this the same reason the morris kunudson 5000 hp cat diesel engines were never replicated. the only reason companies make a product is if there are orders on the books from[8-|] a customer who is willing to pay them. the mk5000. worked just fine. no teck problems other than no one, I. E. railroads did not order any. the emd 90’s were designed to take a 20 cylinder diesel engine in that frame. to date no one has stepped up with the cash accept overseas. why did Baldwin stop building any locomotives. simply because there were no longer any orders. they were number one for over one hundred years.
The MK5000 program mostly fell victim to the fact that MK Rail got into financial trouble (unrelated to the MK5000C).
However I wouldn’t say there were no technical problems as the units were down-rated to 4500 HP when leased to the Utah railroad and eventually rebuilt with the Wabtec version of the 16-645 engine…