running lean?
07-08-2003, 04:38 PM
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running lean?
if we increase our exhaust system and intake size. and have a boost pressure of 35-40psi. with stock injectors, can the engine run lean?
07-08-2003, 04:55 PM
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Re:running lean?
The leaner the better in a diesel. So to speak. You can't really run to lean. The leaner you run, the more fuel you are burning. The more fuel you are burning, the more power you are getting. Besides, running 35-40psi on a stock motor with no box is pointless. You don't have any extra fuel to burn so you don't need the extra boost to burn it. The more fuel you add, the more boost you need.
07-08-2003, 05:09 PM
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Re:running lean?
i guess my real concern is, wasn't real happy pulling my 30fter. last w/e. only had this 96 for 4 mounths now. and i thought it should of done better. Running about 60-65 mph. on a hilly road, it was running about 1150-1200*f around 20-24 boost. do thease numbers sound fair?
07-08-2003, 05:20 PM
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Re:running lean?
thanks BigBlue<br>with my injectors being of a unknown to me, i was worried about the aftermarket stuff already done when bought.<br>sounds good to you sounds good to me.. thanks.
07-08-2003, 05:26 PM
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Re:running lean?
Quick question. Is your EGT pre or post turbo? If those temps are pre turbo, your alright. If those are post turbo, then you are in serious trouble. I don't think Banks upgrades the injectors. I'm not sure though. Sounds to me like you might need a little more boost though. 20-24 seems kinda low. How much smoke are you producing? A light haze at WOT is good. If there's a lot of smoke at WOT, then you need more air.
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07-17-2003, 11:37 AM
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Re:running lean?
The leaner you run, the more fuel you are burning. The more fuel you are burning, the more power you are getting. Besides, running 35-40psi on a stock motor with no box is pointless. You don't have any extra fuel to burn so you don't need the extra boost to burn it. The more fuel you add, the more boost you need.
07-17-2003, 12:21 PM
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Re:running lean?
[quote author=JyRO link=board=8;threadid=16832;start=#160997 date=1058459869]<br>
<br><br>Big Blue - That all sounds OK to me, except the 1st sentence quoted. If you're running lean, doesn't lean mean less fuel and more air beyond the stoichemetric (sp?) level? In other words, more air?<br><br>You're first sentence is confusing me...lean means less fuel. Running a tad on the rich side would cause the haze out the exhaust ... right? And more than a tad on the rich side blows some good smoke ... right?<br><br>- JyRO <br>[/quote]<br><br>BB is right - you have to get past thinking in gasser terms - in a diesel, best power/efficiency occurs at the LEAST smoke and LEANEST mix - where you are burning ALL the available fuel... Burning only PART of the fuel produces smoke in varying degrees, and indicates a RICH mixture that is NOT efficient, and is not producing the best power in relation to available fuel... This is why merely providing more BOOST, above that needed to maximize burning of available fuel, is pointless, doesn't do anything but increase cylinder pressure, since all the fuel has already been burned - NOR is addition of more fuel - and more smoke - beneficial either, since without added air to burn it, it simply blows out the exhaust and creates higher exhaust temperatures...
The leaner you run, the more fuel you are burning. The more fuel you are burning, the more power you are getting. Besides, running 35-40psi on a stock motor with no box is pointless. You don't have any extra fuel to burn so you don't need the extra boost to burn it. The more fuel you add, the more boost you need.
07-17-2003, 01:31 PM
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Re:running lean?
Howdy Gary!
I don't think your reply answered my question. At least not the way I *intended it*. But I do now think I know what BB meant.
Let see if I understand BB correctly. Running lean you burn more fuel - Translated (for my understanding): I think he means that you're more efficiently burning the fuel that is available when you're not running rich. And I agree with that.
But does adding fuel beyond an ideal (most efficient) level cause you to burn *less* fuel? I don't know. What I do know is that some of the extra fuel will not burn efficiently ... thus smoke.
The thing that confuses me most about conversations regarding lean and rich burns, is that I think most people assume there are 2 conditions: 1. Rich, 2. Lean. And because they only consider these 2 conditions, they *say* that lean is better.
However, I *think* really there's (at least) 3 conditions. 1. Lean, 2. Ideal (stoichometric (sp?)), 3. Rich
Something like this: | <------- lean ------------>|<-- ideal -->|<----------- rich ----------->|
My assumption is max power is about here^ ^Haze ^---- Smoke ------^
But where you get max power is NOT the leanest ratio. To the extreme, the leanest ratio is all air and no fuel. And we all know it will not run that way, much less be powerful.
Not only do I agree with this, but I never disagreed either.
Gasser or not, the ideal fuel ratio condition is when the truck doesn't smoke, but a *drop* more fuel and you start getting the haze (yet, the haze level is very very close and is a good measurable (visible) gage for good power).
How many beans do I have in me? Am I completely full? I realize diesels and gassers are different, but logically I can't be too far off.
- JyRO
I don't think your reply answered my question. At least not the way I *intended it*. But I do now think I know what BB meant.
Let see if I understand BB correctly. Running lean you burn more fuel - Translated (for my understanding): I think he means that you're more efficiently burning the fuel that is available when you're not running rich. And I agree with that.
But does adding fuel beyond an ideal (most efficient) level cause you to burn *less* fuel? I don't know. What I do know is that some of the extra fuel will not burn efficiently ... thus smoke.
The thing that confuses me most about conversations regarding lean and rich burns, is that I think most people assume there are 2 conditions: 1. Rich, 2. Lean. And because they only consider these 2 conditions, they *say* that lean is better.
However, I *think* really there's (at least) 3 conditions. 1. Lean, 2. Ideal (stoichometric (sp?)), 3. Rich
Something like this: | <------- lean ------------>|<-- ideal -->|<----------- rich ----------->|
My assumption is max power is about here^ ^Haze ^---- Smoke ------^
But where you get max power is NOT the leanest ratio. To the extreme, the leanest ratio is all air and no fuel. And we all know it will not run that way, much less be powerful.
Burning only PART of the fuel produces smoke in varying degrees, and indicates a RICH mixture
that is NOT efficient, and is not producing the best power in relation to available fuel... This is
why merely providing more BOOST, above that needed to maximize burning of available fuel, is
pointless, doesn't do anything but increase cylinder pressure, since all the fuel has already been
burned - NOR is addition of more fuel - and more smoke - beneficial either, since without added
air to burn it, it simply blows out the exhaust and creates higher exhaust temperatures...
that is NOT efficient, and is not producing the best power in relation to available fuel... This is
why merely providing more BOOST, above that needed to maximize burning of available fuel, is
pointless, doesn't do anything but increase cylinder pressure, since all the fuel has already been
burned - NOR is addition of more fuel - and more smoke - beneficial either, since without added
air to burn it, it simply blows out the exhaust and creates higher exhaust temperatures...
Gasser or not, the ideal fuel ratio condition is when the truck doesn't smoke, but a *drop* more fuel and you start getting the haze (yet, the haze level is very very close and is a good measurable (visible) gage for good power).
How many beans do I have in me? Am I completely full? I realize diesels and gassers are different, but logically I can't be too far off.
- JyRO
07-17-2003, 01:55 PM
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Re:running lean?
"But where you get max power is NOT the leanest ratio. To the extreme, the leanest ratio is all air and no fuel. And we all know it will not run that way, much less be powerful."<br><br>I would hope most would recognize we're talking in relative terms here, rather than absolutes - still, a few do crop up from time to time who think all they need do, is put more boost into their diesels to gain lots more power - MIGHT happen to a small degree IF thay already had a bit more fuel than they were burning - but most likely VERY little! ON the other hand, there are others who assume simply upping the fuel delivery to the Cummins will accomplish more smoke, AND more POWER - WRONG! More smoke for sure, but power will likely go down and EGT will go UP - a big difference between gassers and diesels, is that reducing mixture to a gasser usually INCREASES burn temperature, and burns valves and spark plugs, and CAN damage pistons... leaning mixture in a diesel causes the OPPOSITE, COOLER burn - again, relatively speaking, and within reasonable parameters!<br><br>Naturally, there is a region of "best", or highest efficiency fueling rate - and I suppose it's a judgement call as to whether it's best to run slightly on the "rich" or "lean" side - the condition of your EGT might be the deciding factor in that case...
07-17-2003, 02:03 PM
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Re:running lean?
Gary - I think I agree with your whole reply. I'm sure that at some point (before my exposure to diesels even), I though that blowing more boost would automatically give more power.<br><br>And then those of us who ask and or seek the truth, learn differently.<br><br>- JyRO
07-17-2003, 02:29 PM
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Re:running lean?
question then, If i have no signs of smoke, then is it time to up the stock injectors to match the rest of the upgrades?<br>and if i do that, how much will the egt raise? i feel i am pushing it now.