Increase Boost, when increase fuel?

Discussion in 'Diesel Tech and 24 volts Systems' started by coldtaco, Sep 5, 2006.

  1. coldtaco

    coldtaco

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    Ok, so when do you know you need to increase the fuel from the injection pump as you increase the boost pressure? Just look at your tailpipe until there is no more visible black smoke under high boost? If you have too much boost with not enough fuel what happens and are there any indications on the EGT?
     
  2. brownbear

    brownbear Mod in Hibernation Moderator

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    my thinking is; you increase or decrease the fuel solely on egts. if you are only 850 under heavy load them you can increase the fuel to get more power. increasing the boost will give you more room for fuel adjustment.


    if you are blowing too much black smoke but your egts are not too high, then you will end up turning the fuel down. But the tail pipe doesn;t really tell you what your egts are going to be. I have had next to nothing smoke but really high egts.
     
  3. Gold Boy

    Gold Boy

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    BB, very interesting.

    Sorry to butt in, but I run about 1000f @ 3000rpm under heavy loads outside temp about 35c, with very little smoke.
    So from what you are saying I could be maxed out on fuel increase?

    GB
     
  4. brownbear

    brownbear Mod in Hibernation Moderator

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    where is the pyro probe? You could go up more if your probe is pre turbo. Cause 1250 under heavy load is considered max safe, Or increase the boost and you have room for more fuel. The more boost you add the lower the egt will be untill you max out the effectiveness of the turbo, then it will only blow scorching hot air. Then you need an intercooler to go higher psi. Which inturn will let you add more fuel.

    The stock 13b-t psi is pretty low(6-8?) you could crank it up to 12 psi and add a little bit more fuel.
     
  5. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    I thought is very simple .. IMOP for sure ..

    Search about your max boost safe .. for your engine, then boost your PSI at this number. After that increase fuel, until you reach 1150 under heavy loads or long hills .. and you are done ..

    Other option if you don't really like the smoke .. don't increase as much your diesel in your pump ..
     
  6. Gold Boy

    Gold Boy

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    Thanks BB

    The pyro probe is post turbo - Here is a picture link.

    Post #13
    http://forum.ih8mud.com/showthread.php?t=106923

    Today I observed - 1100f @ 3000rpm with outside temp of 33C.

    :beer:
     
    Last edited: Sep 5, 2006
  7. coldtaco

    coldtaco

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    Pyro probe about 3" after the turbo. Since I did the SeaFoam thing, the highest EGT's I have seen has been 600F, this is at about 12psi.
     
  8. brownbear

    brownbear Mod in Hibernation Moderator

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    then you are at max now. I put my probe in the same spot. unless you crank the boost up to 12, then you leave the fuel there. IMOP
     
  9. brownbear

    brownbear Mod in Hibernation Moderator

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    sounds like you need to try to find out how to calibrate it. Not sure if thats possible. But if you have the manual, look to see of there is section for testing resistance of the probe and wires. The probe should have a resistance value, you can compare your to it.


    If you can't find lititure(?) on it, go to the store you bought your gauge and probe from, put a meter on new probe and see what you get. Then go home and see what your probe reads. But remember both must be cold. Like the engine hasn't run for hours. Any heat and the resistance will be different.


    Can you buy probes seperately? What guage package do you have?
     

  10. Greg_B

    Greg_B

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    Did you have the probe in before the intercooler was installed? Wondering how much your intercooler dropped your EGT's.

    Don't feel like you need to see 1000F or something is wrong. I've a buddy who put a cummins into his GMC lift bed truck. He drives through the mtns all the time to 100 Mile House, with enough of power to move everything (loaded deck, bobcat, etc) and never sees more then 600-700F on his EGT's.

    If you've got the performance you need, and are not seeing high EGT's I would not worry about it; The intercooler is doing it's job! That said you've the room to pump in more fuel and make more power with EGT's that low. You could dial it up till you are happy with the power it's making for your driving situations.

    A diesel is running all sorts of air/fuel ratios as it is fuel throttled, not air throttled like gassers. Your engine takes in the same amount of air on every intake stroke. The turbo installed at the factory increased the air density. By adding the charge air cooler you've in effect increased again the air denisty and increased the amount of oxygen being taken in. The charge air cooler has the nice benefit of cooling the intake air...which will effect your EGT's considerably at WOT. So now you now are seeing lower EGT's given the same amount of fuel being injected.

    If you are not building a race engine, are looking for a moderate power increase which still maintains good engine longevity I would be inclined to find a point that kept EGT's moderate, while not stressing the turbo to early failure (wonder how long a bushing style CT-26 would last pumping out 20psi, or even if a 13BT CT-26 can make that kind of boost?). You might be there...

    The 13BT will probably put out scads of power if tuned: charge air cooled, boosted and fueled. That will come with a price...longveity, which is why I used the words moderate in the paragraph above.

    Dunno if that helped more then made things confusing...

    Simple answer: Your charge air cooler is making sure the air heated from compression through the turbo is cooled, so that is good. Your engine is fuel throttled so if you are at WOT and your reading on the EGT guage is low it simply tells you that you are not using all the available charge air.

    hth's

    gb
     
  11. coldtaco

    coldtaco

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    Anybody run more than 12psi boost on their stock 13B-T turbo?
     
  12. coldtaco

    coldtaco

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    Let me see if I can remember the before and after specs. Before intercooler I was seeing about 8psi max and 750-800F on the egt. After intercooler I am now showing about 12psi max and 600F on the egt, but not always at the same time if that makes sense. I can see 600F with only 10psi boost and 12 psi boost with colder than 600F egt. I have the Westach gauges and probes and such. I will have to see if I can find any specs on testing the egt probe. It's really hard to get the 12psi boost. Before the SeaFoam thing I was showing about 425egt at 57mph and after I am now mostly showing 380+F at 57mph.
     
  13. Greg_B

    Greg_B

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    Did play with the wastegate after installing the charge air cooler?

    Thanks

    gb
     
  14. coldtaco

    coldtaco

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    Yep, that's how I am now getting 12psi boost:)
     
  15. brownbear

    brownbear Mod in Hibernation Moderator

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    ok, have you tried dialing up more fuel?

    With your set up, its possible you got nice cool air. There is no reason to max it out if your happy with performance, as Greg_b says. More power means more fuel used. I am miserly to some extent.

    but it would be good to test your probe, cause you did say you had as sudden egt drop. one day 100 degrees lower....right?
     
  16. coldtaco

    coldtaco

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    Well, today I finally got around to testing the thermocouple. According to the catalog I have, it says that the resistance should be 2.5 ohms. I read 2.8 ohms at 60F ambient temp. The gauges are calibrated at 70F, unless mine was calibrated at 32F for cold applications, which I don't think it was. I also ended up pulling one of the bullet ends off when disconnecting from the wires going to the gauge:crybaby: So I pluged it back on and souldered it. I also put a little bit of dielectric grease on all the connections to try and prevent any chance of any corosion buildup. So I went for a drive afterward and noticed a couple of things right away. First, the EGT would rise and drop almost instantaneously, where before it would rise and fall at a slower rate. Also, now while accelerating I would routinely see 600F where before it would max at 500F on flat ground. At 57 mph it now reads about 480F. Anyway, now what? I emailed the manufacturer and hope to hear back from them with their thoughts. They do list their thermocouples as having a 500hr service life, which this is definitly past.
     
  17. brownbear

    brownbear Mod in Hibernation Moderator

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    depending on how much a probe costs, I would try a new one.

    The spontaneous movement sounds fishy.
     
  18. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    why not try with a digital reader in a dyno . ?
     
  19. coldtaco

    coldtaco

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    Manufacturer says the 2.8ohm reading is well within limits. I probably had a loose connection on the bullet end that came loose and now is tight again and so it seems like it is reading correctly again. Don't have access to any Dino here in Fairbanks. Can't find one in Anchorage, does not mean that there isn't one there.
     
  20. brownbear

    brownbear Mod in Hibernation Moderator

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    AH your north of me. Starting to get the cool stuff. I found the EGTS come down during cold spells too, Sucking in that cool air.

    Good that the probe is OK. I think your right the connection was probably funky.
     

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