Can someone explain to me diesel motor timming. I fully understand timming in a gasser and in fact when building my harley's timming becomes a major concern. On most occassions I will opt for 2 plug heads so that I can start the burn a little later and keep the heat down( keep some of the timming out) now when I read some of the posts about performance I read about advanced timming and lower egt's, I am missing something I know ,but if the friction from the squeeze is what lights the fire then how does timming figure (what are you timming) I guess I am a little lost on this concept, are you increasing the friction ? how does it keep down the EGT'S. I am just trying to get all this in my head ,before I start the bombs, then at least what I do makes some sense rather than just doing what the next guy does because it sounds cool. Thanks for helping out a dummy on this one.

 

[quote author=eieio link=board=8;threadid=23471;start=0#msg220407 date=1070929711]
I guess I am a little lost on this concept
[/quote]

Ditto ;D I too would like to know how this works

 

I'm still trying to figure this one out too, but I think it is kinda the same principal as a gasser, moving the distributor changes when the plug fires in relation to where the piston is on the stroke, I THINK it would also be as to when the injector pump skeets the fuel in the injector, ya know, as to after TDC or before TDC. I guess it all depends on where the piston is on the stroke as to how the fuel will be burned. It sure would be easier with a TIMING LIGHT

 

On a diesel, you're timing the start of the fuel injection. It helps to think about it as similar to spark timing on a gasser. Retard it too far, you run hot and have no power - just like a gasser. Advance it too far, you run hot and bang holes in the pistons - just like a gasser. Timing is adjusted by rotating the injection pump on 12 valve engines, and by playing with the computer on 24 valve engines. The factory timing is a little conservative, so a little advance helps lower the EGT (more fuel burns before the exhaust valve opens) and raise the power due to higher cylinder pressure at TDC. Excessive advance can cause cracked pistons and blown head gaskets. Hope that helps, feel free to ask for clarification if anything's fuzzy.

 

Engine parameter: TIMING is:
RETARDED ( - ) ADVANCED ( + )
EXHAUST TEMP increases decreases
CYLINDER PRESSURE decreases increases
INTAKE MANIFOLD PRESSURE
(BELOW P-TORQUE) WASTEGATED increases decreases
BSFC (brake specific fuel consumption) increases decreases
NOX (oxides of nitrogen) decreases increases
HEAT REJECTION increases decreases
HYDROCARBONS (HC) increases decreases
BLACK SMOKE: 1000RPM increases decreases
BLACK SMOKE: PEAK TORQUE decreases increases
BLACK SMOKE: RATED increases decreases
WHITE SMOKE: < 1000RPM increases decreases
WHITE SMOKE: > 1000RPM increases decreases



Does this help any? If your confused on how to read it just reply here.

 

I think you should have said, NOW that you ARE confused, feel free to ask questions . What's the easiest way to "adjust" the timing????

 

I am not so confused now actually it makes sense. I understood txredneck post and made sense up to a point. It seems there is some latitude in the timing , and it seems that our CTD is under timed. I think like a gasser though that too much timing would make her run hot. thanks guys this deisel education is something for a lifelong go fast gasser guy.

 

Eieio,

And it's not the "friction" that makes the heat it's simply the compression that makes the heat. When the piston get to near top dead center the air is hot enough, from simply being compressed, to ignite the fuel and so all that's needed is for the injecton to start and the burn starts. So you start the burn where you want by setting the timing of the injection.
That's why the compression is so high in diesel compared to a gas engine.
Wetspirit

 

eieio - uhhh, you kinda have friction...depending on how you are looking at it. This is how I understand it and I maybe wrong. Any Chemistry experts please speak up. Also, I am no Chemistry major. However, when compressing the "air", the "air" molecules become excited and begin to move rapidly. Now you are forcing these molecules into a smaller area by the nano-second. They move faster and faster in the smaller and smaller area. This causes the molecules to hit one another and rub together. This is your friction or temperature increase. Then add the fuel that has a specific "flash point" and we get our BOOM that provides the power we all love. Your timing is when to add our fuel to this compression of the "air".

JKE

 

'Read this series of articles and you'll know more than most of us here. http://www.dieselinjection.net/frames.html This shop builds high power engines and retards the timing when building them. When the timing is advanced, a diesel engine will more closely resemble a gas engine in throttle response. The trade-off is high combustion temps, more stress on connecting rods, more wear on bearings, etc.-Well, it's all in the articles.

 

You could argue chemistry or thermodynamics..

Simply, when you add energy to compress a gas, if all conditions are equal with no leakage etc, you create heat energy proportionate to the compression ratio and the specifics of the gas composition.

The table of increased/decreased should be formatted in a spreadsheet an posted in the tech facts area. Good information there.

J-eh

 

Timming adj "Tim-ing" To give one the name "Timothy"
Timing adj "Time-ing" To coordinate an event; set event parameters to match those of another; to set ignition timing on an engine; . . .

OK I couldn't help being a smartA**

Vaughn

 

I was waiting for someone..... ;D

Vaughn wins !


Ron W.