diesel fueling questions. (trying to learn)

[turbhoe]

i'm just kinda getting into the diesel thing and its hard to find some of the info i'm looking for. basically i wanna know can you run a diesel too lean? say you are running 25psi and have a light haze at WOT and you take that same tune but manage to some how run say 40 psi. will that cause a lean issue like a gas motor or will it just not make any more power? i know the goal is to burn fuel to make power and you need air to burn the fuel.

also for cruising down the road can you dial the fuel way back with out knock? i've searched for ideal AFR's but it seems like the ideal AFR at wot is a light haze of smoke lol.

i had more to write but i got interupted and forgot wtf i was going to say.

 

[TrentNell]

AFR isn't really relative on a diesel like it is on a gasser , with that said there still is a hypothetical Stoichiometric sweet spot but that is richer than most think or run , but you can run lean or rich with out mechanical failure , the main changes will be HP difference and EGT difference .

 

[SSchmi5519]

Yes, where in a gasoline engine a ratio is important, in a diesel application fuel is the only determining factor. The more you increase the air, the more fuel you can burn. The more fuel you burn, the more power you make.


Sent from my iPhone.

 

[turbhoe]

i would guess that the hypothetical Stoichiometric is more for emissions?
so am i correct in saying more fuel higher egt more air lower egt and more fuel gives more power? as long as you have the air to burn said fuel.

 

[SSchmi5519]

i would guess that the hypothetical Stoichiometric is more for emissions?
so am i correct in saying more fuel higher egt more air lower egt and more fuel gives more power? as long as you have the air to burn said fuel.

Yes the ratio is more for efficiency than anything. Running rich you just waste fuel in the form of black smoke. It is not really possible to run them lean, as without the fuel, the engine will struggle to turn.

Yes, with the same amount of fuel, more air will lower EGT. With the same amount of air, power will increase with fuel until black smoke is present. If you see black smoke at full boost, you are lacking air.

We have no "throttle body" that regulates air. The engine is free to use whatever air it can. Due to this, think of the throttle pedal as a regulator for fuel only. The air or boost is just a result of the heat created by the fuel in the first place.


Sent from my iPhone.

 

[GeneralTJI]

EDIT: Didn't read your last post: Best WOT place is just cleaned up.... (enough air to clean up smoke, too much air means your working your turbo harder than it needs and loosing some efficiency) You can't run too lean. In fact, running rich in a diesel makes for more heat. Much different from gasoline.

so am i correct in saying more fuel higher egt more air lower egt and more fuel gives more power? as long as you have the air to burn said fuel.

Pretty much yes. As with everything it's a balancing act.. injection timing is important as well.

 

[turbhoe]

Yeah I knew no throttle body but I wasn't sure if it's still considered WOT but it's a pretty universal term. thanks for the help guys five learned alot from reading. I usually try to research a shit ton before I do or ask anything. That's how I built and self tuned everything I've done. I've tuned many gazette for people just never diesel so I want to know how notto break things. From what I've read and understood too much timing and too long of an injector pulse is not a good thing. Better to have enough fuel to squirt in a shorter time then not enough and take too long to do it. Does this sound generally correct?