ex Budd man

Why is EMD going to four stroke engines?

Cause two stroke diesels, just like lawn mowers and small tools are biggest polluters.

Two stroke gas engines mix fuel and lube oil, two stroke diesels do not. I can't see them being any dirtier than a four stroke diesel, unless it has a turbo failure.

maybe you can't see it , but EPA sure does, look at their TierII restrictions.

ex Budd man wrote:Why is EMD going to four stroke engines?

Where have you been. EMD dabbled in 4 stroke design 15 years ago and seems very happy to continue with the hugely successful 710 series. I would like to know what the scientific basis is for this prejudice against 2 stroke diesel engines other than religious reasons.

EMD's development of their four cycle prime mover, the 265H, hit a snag with the disintegration of parent GM. Now that they are independent I've heard that the refinement 265H is continuing. Three hundred of them are on their way to China for locomotive service. Due to overall fuel efficiency and exhaust concerns, the future belongs to four cycle engines... not divine intervention.

Nobody has answered my question - what is the scientific reasoning for the supposed superiority of 4 stroke engines.

Most two-stroke engines don't (and can't) have fully variable valve timing, which can help control emissions and increase power for a four-stroke, and don't burn their fuel as completely as a four-stroke engine. They're also more difficult to fit with pollution controlling fixtures like exhaust gas recirculation.

mtuandrew wrote:Most two-stroke engines don't (and can't) have fully variable valve timing, which can help control emissions and increase power for a four-stroke, and don't burn their fuel as completely as a four-stroke engine. They're also more difficult to fit with pollution controlling fixtures like exhaust gas recirculation.

Thankx for the clarification. I noticed that Detroit Diesel is no longer building two strokes either............. Gee you look away for a minute and someone changes everything!

Evertime rings go by airbox vents moer oil gets burnt up. Oil does get mixet in.

The air box and crankcase are not common so oil can't be drawn in to the combustion chambers that way unless the cylinder head oil returns leak into the air box.

Piston rings scavenge oil from cylinder walls, when those rings pass the airbox ports, the oil will get in combustion cycle.
This why on EMD's oil is not changed, its just added.

DutchRailnut wrote:Piston rings scavenge oil from cylinder walls, when those rings pass the airbox ports, the oil will get in combustion cycle.
This why on EMD's oil is not changed, its just added.

Any engine will draw oil past the rings if they are worn, two stroke or four. One would think since constant positive pressure in the air box would lessen this effect. I may be barking up the wrong tree here. Any EMD techs care to share?
As to changing oil, Septas three SW-1200 got oil changes on a regular basis.

not talking about oil getting by rings, but rings passing port, dumping oil strainght into airbox.
As for SEPTA maybe they change oil cause their a bus company.

DutchRailnut wrote:not talking about oil getting by rings, but rings passing port, dumping oil strainght into airbox.
As for SEPTA maybe they change oil cause their a bus company.

You said the 'B' word, go wash your mouth out.