Henryv111111
Member
Did the Detroit Diesel Series 71 motors have a crank case for lube oil. I know the 2 cycle small motors mix the fuel and oil. Its a dumb question but I never worked on one.
Thank you
Thank you
- Thread starter Henryv111111
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Anonymous-0
Well-known Member
Yes they do. They also have conventional exhaust valves.
Janicholson
Well-known Member
All Detroit diesel 2 strokes used pressurized air to blow the exhaust out of the top of the cylinder through regular exhaust valves (2or 4 of them, no intakes at all)
the pressure is produces by a supercharger. stuck to the side of the engine, blowing into a plenum surrounding the middle of the cylinder wall. Each cylinder has perimeter ports in a ring. These are located just above the point of lowest travel of the piston.
Fuel is injected and ignites with max pressure just after TDC.
Piston moves down expanding the heated combustion gasses.
Crankshaft drives the blower, pressurizing the air in the plenum.
As the piston clears the ports, the exhaust valves are opened (cam operation).
The compressed air purges the exhaust out of the cylinder and fills it with air.
Compression happens heating the air for the next injection cycle.
The crank case is closed and operates just like a 4 stroke. Jim
the pressure is produces by a supercharger. stuck to the side of the engine, blowing into a plenum surrounding the middle of the cylinder wall. Each cylinder has perimeter ports in a ring. These are located just above the point of lowest travel of the piston.
Fuel is injected and ignites with max pressure just after TDC.
Piston moves down expanding the heated combustion gasses.
Crankshaft drives the blower, pressurizing the air in the plenum.
As the piston clears the ports, the exhaust valves are opened (cam operation).
The compressed air purges the exhaust out of the cylinder and fills it with air.
Compression happens heating the air for the next injection cycle.
The crank case is closed and operates just like a 4 stroke. Jim
Don't think any naturally aspirated 2-stroke Diesels were made in America although some Fairbanks-Morse engines could be an exception. I dunno.
Half a dozen of those nat-asp Diesel engine designs were made in Europe however. Lanz and Field Marshall come to mind. They were around 40hp. Both of them had oil filled crankcases.
Bob M listed many of the GM two-stroke models. He may have passed over some the huge tug boat engines with pressure scavenged engines. The blowers were centrifugal turbines that pumped large amounts of high static pressure air. Not as noisy as the 2 and 3 lobed Roots blowers.
Half a dozen of those nat-asp Diesel engine designs were made in Europe however. Lanz and Field Marshall come to mind. They were around 40hp. Both of them had oil filled crankcases.
Bob M listed many of the GM two-stroke models. He may have passed over some the huge tug boat engines with pressure scavenged engines. The blowers were centrifugal turbines that pumped large amounts of high static pressure air. Not as noisy as the 2 and 3 lobed Roots blowers.
tractorsam
Well-known Member
Just to be picky and because it's an unusual setup the Field Marshall actually uses a dry crankcase with a separate oil sump. The oil pump meters a fairly small amount of oil to the various places (I believe it has six outputs) and when the oil collects in the bottom of the crankcase it is blown by positive crankcase pressure (piston traveling to the rear) up a tube to the top of the engine. On its way back to the sump it gravity feeds through the oil filter. Also due to the charge air coming through the crankcase a percentage of the oil is drawn in with the air and lost. The result is anyone driving said tractor having a very bad case of the black spots! Sam
Bob M
Well-known Member
Wardner - I think you are right - there were no naturally aspirated (ie. w/o scavanging blower) diesels made in the US.
Also Fairbanks-Morse opposed piston diesels ARE blower scavanged, same as the Junkers (Germany) and Napier (England) opposed piston engines.
----
Other useless 2 stroke diesel trivia:
- Detroit (and I believe also EMD) DO use gear-driven turbine compressors on certain 2 stroke diesels. There was a Euclid rock truck with a turbine-scavanged 6-71 where I worked summers in college. Also a 12V-71 powering an air compressor. (My observation is they were every bit as noisy as their Rootes blown sisters.)
- Most modern tugboats' prime movers are EMD (2-stroke) or General Electric (4-stroke) locomotive diesels modified for marine service. Larger ships' prime movers however come from overseas with names like Sulzer, Wartsila, Pielstick, MAN, etc.
- In the early 70's Chrysler made a half-hearted attempt to break in to the truck diesel market with Japanese-built 2 strokes similar to the Detroit 6-71 and 8V-71. They were offered under the Chrysler-Nissan banner. The attempt was a complete failure.
Also Fairbanks-Morse opposed piston diesels ARE blower scavanged, same as the Junkers (Germany) and Napier (England) opposed piston engines.
----
Other useless 2 stroke diesel trivia:
- Detroit (and I believe also EMD) DO use gear-driven turbine compressors on certain 2 stroke diesels. There was a Euclid rock truck with a turbine-scavanged 6-71 where I worked summers in college. Also a 12V-71 powering an air compressor. (My observation is they were every bit as noisy as their Rootes blown sisters.)
- Most modern tugboats' prime movers are EMD (2-stroke) or General Electric (4-stroke) locomotive diesels modified for marine service. Larger ships' prime movers however come from overseas with names like Sulzer, Wartsila, Pielstick, MAN, etc.
- In the early 70's Chrysler made a half-hearted attempt to break in to the truck diesel market with Japanese-built 2 strokes similar to the Detroit 6-71 and 8V-71. They were offered under the Chrysler-Nissan banner. The attempt was a complete failure.
Bob,
That's interesting about the small Detroits using centrifugal blowers.
I seem to recall reading on the Yahoo DD forum site that some constant load engines were not fitted with power robbing mechanical blowers. They were only pumped with turbochargers. Don't know how they got the turbos up to speed but they may have used an air jet similar to a Pelton wheel in hydro plants.
It's been said the roots blowers in some DD turbo engines actually are "loafing" when the turbo is wound up. That means the blower is being spun by the turbo air on its way to the airbox. Some have by-pass air circuits for greater efficiency.
That's interesting about the small Detroits using centrifugal blowers.
I seem to recall reading on the Yahoo DD forum site that some constant load engines were not fitted with power robbing mechanical blowers. They were only pumped with turbochargers. Don't know how they got the turbos up to speed but they may have used an air jet similar to a Pelton wheel in hydro plants.
It's been said the roots blowers in some DD turbo engines actually are "loafing" when the turbo is wound up. That means the blower is being spun by the turbo air on its way to the airbox. Some have by-pass air circuits for greater efficiency.
heavy hauler too
Member
They hold 10 gallons of oil, but put 9 in that will stay in longer!!ha.
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