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  • ex Budd man

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

 #640790  by ex Budd man
 
Why is EMD going to four stroke engines?
 #640801  by DutchRailnut
 
Cause two stroke diesels, just like lawn mowers and small tools are biggest polluters.
 #641605  by ex Budd man
 
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.
 #641715  by DutchRailnut
 
maybe you can't see it , but EPA sure does, look at their TierII restrictions.
 #641779  by RickRackstop
 
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.
 #641834  by D.Carleton
 
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.
 #641843  by RickRackstop
 
Nobody has answered my question - what is the scientific reasoning for the supposed superiority of 4 stroke engines.
 #642540  by mtuandrew
 
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.
 #642558  by ex Budd man
 
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! :wink:
 #642607  by bystander
 
Evertime rings go by airbox vents moer oil gets burnt up. Oil does get mixet in.
 #643006  by ex Budd man
 
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.
 #643030  by DutchRailnut
 
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.
 #643385  by ex Budd man
 
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.
 #643426  by DutchRailnut
 
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.
 #643519  by ex Budd man
 
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. :wink: