Good Diesel Tech on Fairbanks Morse

[Vaughn MacKenzie]

Here's a web page with some interesting diesel tech, especially discussion the 4-cycles and injection timing & duration (this is a common subject for the 3rd Gen guys).



http://members.shaw.ca/diesel-duck/machinery_page/diesel_engine/diesel_engine.02.htm



Vaughn

 

[HoleshotHolset]

I don't agree with this picture 100%: #ad




Stroke 3 shows the fuel being injected as the piston is going down. The fuel starts injecting as the piston comes up on the compression stroke...



The diagram could be misleading... that's all I'm saying...



Matt

 

[ProMac1K]

True!



Didn't notice that until you mentioned it.

 

[HoleshotHolset]

Plus...



The rod looks like it is hitting the liners... and the crank looks like it's hitting the piston. :-laf



Matt

 

[ProMac1K]

:-laf



Plus...



How are you supposed to get bolts through those rods?



Why are all the counterweights lined up with each other? J/K I know, they're only showing one cylinder.



Looks like the liners are kind of short for the stroke, in a way.



What kind of injection is that? Looks like the fuel is spread pretty wide for the size of the piston. Maybe not.



Just some things that came to my attention.



I never knew exhaust came out in arrows.



Okay, i'll stop. Some crazy CAD anyway.

 

[nickleinonen]

#ad




this pic is way cool...



when i was in college, there was a diesel injection video made by toyota that showes diesel combustion from through the piston [they had a glass window in the piston and a camera viewing up] and it was cool how you saw the spray pattern and how the fuel ignighted and all...

 

[Vaughn MacKenzie]

Holesett I don't think that pic is as misleading as it may seem initially (injection on power stroke).



It says on that page that injection starts at 10 degree TDC and ends at 35 degress ATDC. I would say in the diagram the piston is about 35 deg ATDC (after TDC) at which point it says "shortly after injection ends cylinder pressure peaks. " So I think they are trying to demonstrate the power stroke at the approximate point injection ends and the maximum thrust of the power stroke.



Vaughn

 

[Bill Lins]

I always thought the fuel was injected as the piston was moving up during the compression stroke. It then ignites & pushes the piston downward, creating a "power" stroke, doesn't it? (not to be confused with a Ford diesel engine)

 

[Vaughn MacKenzie]

Bill it starts before the piston reaches the top but injection continues past TDC quite a ways (to 35 deg for this particular engine).



Injection start point depends on the engine. 12-valve guys like to set theirs around 15 deg. before TDC. GM 6. 2L is around 5-8 degress BTDC.



The 3rd Gen Cummins inject pretty late into the power stroke but I'm not sure how far. That is one of the problems the TST CR is causing for the 3rd Gens, it extends fueling so late into the power stroke the piston is well down and fuel is still burning during the exhaust stroke. . . hence EGTs into the stratosphere and destroyed turbos.



Vaughn