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Injector flow rates, max HP, BSFC calcs...........

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  • Injector flow rates, max HP, BSFC calcs...........

    Okay here is the deal.

    I have Bosch 0 280 150 701 injectors and there are two locations on the web that say they are 240cc/22lb injectors @ 3.0 bar. In the LENZ injector table, it says the injector is 266ml (same as cc from another conversion chart I found) @ 3.0 bar. Which one is right?

    I changed the fuel pressure in the LENZ (it only effects the duty cycle graph) to 4.0 bar and now the new flow rate is 329ml.

    My questions are:

    What is the actual flow rate of these injectors @ 3.0 bar?
    What is the max HP with .50 BSFC, 80% and 3.0 bar, 4.0bar?
    Is the max HP derived from the flow rate at max TQ?

    I am just trying the figure out if I need to upgrade these injectors before I go an waste a whole day (3hrs there, 3hrs back + dyno time) going to the dyno to get her fully tuned.

    With the fuel pressure @ 48psi I was running out of injector at 5500 rpm @ 12.8afr. I have since raised the fuel pressure to 58psi/4bar and have not been able to do a full test comparing the duty cycle graph with the new pressure.

    If I could judt verify the flow rate at a given pressure then I can calculate the limit of these injectors.


  • #2

    I can't answer all your questions, but maybe I can help.

    I found a couple of locations listing flow rates from various injectors, and the Bosch 0 280 150 701 was always listed as 240cc injectors. Try looking at:

    Interestingly, they do not list at what pressure the injector flows 240cc.......

    I think our motors are "similar", and I am using the Accel 32 pound (336cc) injectors, and there is no indication I can detect that they are "too much". At max power they are at about 80% capacity, which as I understand it is about what you want. This is running them at 3 bar (42 PSI). There is a setting on the Lenz that allows you to adjust for 336cc injectors, which obviously is what I am using.

    With my old EMS I was using the "Sport EVO" (green) injectors, and had them blueprinted at R/C Engineering. They flowed an actually 310cc at 43 PSI. That leads me to believe, intuitively at least, that the stock injectors would likely be more on the order of 266cc. But I am just speculating there. I think the only way to be "sure" would be to have them blueprinted. If you are going to use them that would not be a bad idea anyway.

    But what I am getting at, is that if 310cc injectors were "right" for the Sport EVO, I would think the 336cc ones should be about right for my application since the output of my engine is a bit beyond Sport EVO spec. IIRC you have a 2.5 with Schricks and all, so I would think 336cc injectors would be pretty close to the mark for yours also.

    There is certainly some room for overlap on using injectors, and any given engine I believe could be tuned to run fine on injectors with a range of flow rates. This is particularly true if you have an adjustable FPR. All the information I could come up with said that when in doubt, go with the higher flow injector. That is kind of what I did, and while the 336cc injectors could be slightly "much" for my car, they seem to be working fine.

    Accel also makes a 30lb (315cc) injector, which would be another option. This is particularly true since it sounds like you can adjust fuel pressure if they ended up falling slightly short on capacity. If "Accel" sounds too Camaro/Corvette for you, I will mention that they are supposedly made by Bosch for Accel, and come already balanced as a set. I only mention them because they have a wide range of flow rates and they are easily available.

    I do know that if you change injectors you will pretty much be starting over with AFR tuning....but I am sure you know that.

    I should also mention to other readers (non-Lenz users) that the Accel injectors are high impedence and I do not think they will work properly with the stock Motronic......



    • #3
      No 2.5l for me, I'm still trying to blow up the 2.3l.:sosad:

      The reason I was asking is if you look in the LENZ table, it says these injectors flow 266 @ 3.0 bar.

      I guess I'll have to get the injectors blueprinted one day to find out for sure.



      • #4
        The reason I was asking is if you look in the LENZ table, it says these injectors flow 266 @ 3.0 bar
        I know it does. I just think that might be the LEAST reliable figure of the others we have seen. Particularly if you consider the "quality" of the rest of the Lenz documentation.

        Cleaning, balancing, and blueprinting a set of 4 injectors cost $100 at RC Engineering about a year ago. About a three day turnaround. Money well spent IMHO, particularly if your injectors have some miles on them.
        Last edited by Ironhead; 07-11-2004, 09:25 AM.


        • #5
          I tuned an engine for a friend on stock 240 cc injectors but at 4.5 bar.
          he runs 284/284 schrick cams, large airbox and has 2.3l.



          • #6
            Originally posted by John
            I tuned an engine for a friend on stock 240 cc injectors but at 4.5 bar.
            he runs 284/284 schrick cams, large airbox and has 2.3l.

            Okay, please elaborate on the duty cycle if you know it, max power (estimated).....etc.



            • #7
              how about they have a spreadsheet for calculations

              88 M3 - LACHSSILBER/M TECH
              89 M3 - ALPINEWEISS II/SCHWARZ
              85 323I S52 - ALPINEWEISS/SCHWARZ


              • #8
                Originally posted by Reelizmpro
                how about they have a spreadsheet for calculations
                I did that, but if the starting numbers are off then the whole deal is off.