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Second stage power adder

Discussion in 'FAST Support Forum' started by howedeman, Dec 4, 2013.

  1. howedeman

    howedeman Member

    Joined:
    Apr 3, 2013
    I am running the XFI and have switched over to running a dry system so that I can have a second stage of Nitrous. I have had good results with the first stage. When I tried to use the second stage the computer energized the the second set of noids, changed timing but did not add the fuel. I am using the PA fuel table as additive which worked for the first stage just fine. I am adding about 85 lb/hr for the first stage then 40 lb/hr on second. The way it acted it seemed like when the second stage activated the additive dropped down to the 40 instead of adding 85 and 40. It back fired and fireslotted the head, not a happy camper! I was understanding that the second stage was supposed to be added to the 1st stage as accumulative action. Any ideas would be helpful. I am going to have some time to think about it while I fix my head! I tried to post the log and tune but wont let me for some reason.
     
  2. TurboNova

    TurboNova Active Member

    Joined:
    Jan 30, 2009
    Location:
    Lake Havasu City AZ.. but mostly travel tuning
    The fuel per stage is a overall adder, so the 1st stage is the amount of fuel overall extra. When it switches to the second stage it goes by the amount of timing only in the second stage and only in the second stage fuel. So if you are using it then the timing will have to be the amount of total timing and total extra fuel you will want with both systems on.

    "This is a 2D table of injector flow rate (in lbs/hr) vs. RPM. There are three separate curves corresponding to the first three power adder stages. Depending on settings in Power Adder Global Parameters, these curves either do nothing, define the total amount of fuel used, or define an additional amount of fuel to be added during power adder operation.

    The [TAB] key toggles between the curves. The set points on the RPM axis can be changed to suit your particular application. To change a set point, move the cursor over it, (the cursor will change to a pointy finger) double click on it and enter the new value. NOTE - Keep in mind that each set point must be a greater value than the previous set point."
     
  3. howedeman

    howedeman Member

    Joined:
    Apr 3, 2013
    Yes, thank you for quoting what is in the help index, but this part (or define an additional amount of fuel to be added during power adder operation) can be misunderstood that the second stage is added to the first stage. It does not state clearly that each stage is the total amount of fuel being added. Where in the global parameters does this "define the total amount of fuel used, or define an additional amount of fuel to be added during power adder operation." determine which happens? NO WHERE does it ever say that what ever stage is activated, that is the total amount of fuel being added! Because of this *Banned**Banned**Banned**Banned* it torched my head! Thank you for clearing this up, I do appreciate it, just wish the instructions were more clear about this.:(
     
  4. TurboNova

    TurboNova Active Member

    Joined:
    Jan 30, 2009
    Location:
    Lake Havasu City AZ.. but mostly travel tuning
    You have three choices in the PA parameters.

    1. OFF no fuel is added

    2. Fuel added is exclusive so none of the fuel from VE table is looked at. This fuel is 100% from the "Power Adder Fuel Tables" only and total amount of fuel is per stage, each stage is separate and don't add together.

    3. Fuel added is additional to the VE table and is added from the "Power Adder Fuel Tables" each stage is added separate and don't add together.

    besides these three you can add a supplemental fuel % of fuel per stage in each stage. So stage 1 is 10% more fuel but when stage 2 comes on you need stage 1 fuel % plus what you want for stage 2 as the supplemental fuel %

    In PA mode

    "For example, assume the 1st stage has Timing Retard set to 10* and that the 2nd stage needs to be retarded an additional 6* - for a total retard of 16*. In this case, the 2nd stage Timing Retard would be set to 16* (the total retard) - not 6* (the change from the 1st stage)."

    The fuel tables work the same or if you are using the supplemental fuel % each stage has to work as the stage you are going to get fuel from. They are not cumulative each stage setting is their own setting. So when you are on stage 2 nothing from stage one is active anymore only the stage 2 settings. Remember that when in PA modes all PA settings are active no matter what you may be using or not. Make sure all parameters are set up for what you need.
     
  5. wayney

    wayney New Member

    Joined:
    Jul 28, 2016
    know this is an old post but I am getting ready to add a dry system. so couple questions.....

    1. I am planing on using the inj. lbs per hr vs rpm table to ADD fuel . is this total lbs per hr added to the engine or per cylinder ?

    2. If i did a second stage the second stage would have to represent fuel needed for both stages correct ? or just second stage?

    3. if the nitrous jet and pressure is constant throughout the rpm range why would the fuel not be constant lbs per hour ?

    thanks, wayne
     

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