2 Stroke Diesels?

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Sep 14, 2005 | 02:23 PM

#31

76supercab2

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Dorkpunch, Thanks but you're describing the gasoline 2 stroke cycle. That I understand. The diesel 2 stroke cycle is different. From Fixnair's link:

"A two-stroke cycle has also been used for some diesel engines. As the fuel is injected directly into the cylinder, the lubrication of the crankshaft must be independent in these engines. There is no mixing of lubricating oil into the fuel."

Fixnair, thanks for the link. That clears up a lot. To think there's actually 3 different architectures of 2 stroke diesel engines.

Sep 14, 2005 | 03:17 PM

#32

dorkpunch

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"If the crankcase is not used as an air pump, some other means of forced induction is required, and is often used for efficiency in any case. The intake air must be under pressure, since the engine does not have an induction stroke and cannot suck the air in by itself. A low-pressure supercharger (blower) is needed at minimum, but many are turbocharged."

Missed this part on my first time through his link. Learn somethin new every day, dontcha?!

Sep 15, 2005 | 03:10 PM

#33

ford4.9

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So I don't get where the oil is coming from? There is no forced induction into the crankcase only into the combustion camber which does fit the model of the two stroke diesel that I have seen. Unless there is mass amounts passing by the rings, there is no reason that i could tell for the motor to be a oil puking pig?

Sep 15, 2005 | 04:15 PM

#34

F150daniel

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From: spartanburg, SC

Detroits have a intake that goes to the ports in the sleves that is seperate from the crankcase.

They puke oil out of the crankcase vent(called "slobber tube") probably because of blowby. There a 6-71T at the station with only 50K miles, it hardly leaks two drops after you park it.
It only revs to 2400, it pulls good top end till it hits the rev limmiter.
Stomp it from a stop and it revs to 1200 then takes off.
I just don't know why it revs so slow, it takes about 4 sec to go from idle to 2400 in neutral.

Turbo and nonturbo detroits have different blower ratios.

They will not run with out the blower at all.

Last edited by F150daniel; Sep 15, 2005 at 04:27 PM.

Sep 15, 2005 | 06:05 PM

#35

fellro86

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From: Marengo, Iowa

you also have to consider blower seals. The blower housing is oiled by the crankcase oil as well.

Sep 15, 2005 | 08:52 PM

#36

76supercab2

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Quote:

Originally Posted by ford4.9

I'm going to take a WAG at this. Please correct any misinformation. There is no intake valve. The intake port is in the side of the cylinder wall. As the piston moves it covers or uncovers the port through the cycle. When the piston is down the port is uncovered and the air is blown into the cylinder.

When the piston is up the port is covered and the air is blown into the side of the piston. Unless there is a ring at the bottom of the piston, the air presure probably leaks by the side of the piston into the crankcase. The crankcase is then pressurized and the seals may suffer or oil gets blown out a port in the crankcase somewhere.

Sep 15, 2005 | 09:08 PM

#37

fellro86

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From: Marengo, Iowa

I think you have it right there.. it's been so long since i messed with one, i overlooked that fact... I recalled the cylinder layout, but not that one little detail...

Sep 16, 2005 | 09:44 AM

#38

tjay460

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From: Spokane, WA

The Detroits I have seen have a slobber line on the blower. This line slobbers if the blower seals start leaking, keeping the oil out of the intake. The rest of the leaks I think are poor gasket design, or part fit. We considered them externally lubercated. Fighting all of the leaks was an exercise in futility. These engines can be configured into almost any intake/exhaust configuration imaginable. There were even kits to bolt them together in series. We always joked that the 6-71 was a diesel converter. It converted diesel into noise. They started hard in the cold and were not powerhouses. I'm sure the new ones are better because I believe they are 4-stroke now.