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Lose of power at higher rpms

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    Lose of power at higher rpms

    Engine specs:
    Everything is new or rebuit.
    M20b30
    Ported/polished head
    +1mm valves
    272 billet cam
    10:1cr
    S50 crank/s52 rods/custom pistons
    19lb injectors
    Protune Long tube headers into dual s50 cats
    New-ish fuel pump
    Rebuilt AFM
    Stock intake manifold
    Custom tune, still a work in progress. Afr is 11:1 throughout the range.

    The car pings pretty bad when it is hot outside even when running rich. And I'm clearly not getting the peak horsepower for that amount of torque.

    For a healthy engine what do you think is limiting the power?

    Attached Files
    Last edited by Cabriolet; 12-21-2018, 01:27 PM.
    Much wow
    I hate 4 doors

    #2
    That's super rich, my guess would be the tune is the limiting factory, or whatever is causing it to run that rich.

    Are you sure its pinging? It seems like if it's that rich, its going to miss randomly before it pings.
    Originally posted by wholepailofwater
    Q
    :devil:


    WTB: Dove Grey e36 Front Door Panels (2 door)

    Comment


      #3
      Doh I messed the afr numbers. Plz see the graph, the are good 14-13 throughout the pull
      Attached Files
      Much wow
      I hate 4 doors

      Comment


        #4
        the afr numbers are from a tailpipe sniffer? They can read leaner than a wideband closer to the motor by .5-1 AFR.

        Are we also assuming the valve clearances are within spec?

        What does the timing map look like?
        '84 318i M10B18 147- Safari Beige
        NA: 93whp/90ftlbs, MS2E w/ LC, 2-Step
        Turbo: 221whp/214ftlbs, MS3x flex @ 17psi

        Comment


          #5
          as to the question that's limiting power
          - AFM, piss it off and get a standalone and a good tune (why use agricultural EFI on a big $$ rebuild)
          - stock intake limits power alot but you are still down on whats possible
          - 272 cam is too small (not enough lift or duration) to make it peak hp rpm near what it does with a smaller engine when used with stock manifold.
          - are your pistons generic type? that might be why youre getting pinging and why youre timing is not allowed to be optimal
          - who did the head?
          Last edited by digger; 12-22-2018, 11:37 PM.
          89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

          new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

          Comment


            #6
            Jaxx, the numbers are from the wide band o2 just past the x pipe. pre-cat. Yes, valves are dead on .01+-.002" and i don't have the timing map. the tuner has that but i think we need to do more work on the tune.

            Digger, i live in nazi-CA, you keep it stock here or else you can end up popping the hood and ending up with a fat ticket. the car needs to appear stock. i've seen plenty of people run 200+ with the stock afm. i may go RHD ITBs+haltech but there is a ton of risk.
            As for the 272, bimmerheads advised using the larger cam but i really need it to be driveable in traffic. we have traffic like no other place here in CA. i am thinking i should have gone with the 288. but i do have +1mm valves.
            the pistons are nice ones from Ross:

            bimmerheads did the head. they ported it, put larger seats in, new guides, etc.
            Much wow
            I hate 4 doors

            Comment


              #7
              working with what you have i would check cam timing to see if its advanced. with a small cam like that it will want a bit of retard to it if you want it be happy pulling to 7k.

              AFR look fine, the timing probably still needs to be optimized.

              you could probably conceal a PNP MS setup pretty well if its purely visual, even a gutted M30 AFM to make it look period correct

              its true that a stock manifold doesn't like much overlap it makes idle and low speed suffer, and that will be the case if you go upto a 288 but there is some middle ground.
              Last edited by digger; 12-24-2018, 04:19 AM.
              89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

              new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

              Comment


                #8
                you think he can send you that timing table?
                my m30 picked up some hp after 5k with *2 more advance.
                *2 more before 5k would lose like 7hp so it's a fine line.
                looks like you're missing 20hp though

                also i would go with a bigger cam it's not bad. i got a 293 or something like that
                from cat cams. feels normal.
                has alittle bit of cam sound in the exhaust but isn't felt driveabilty wise.
                wish i went with their 300 for more revs.
                Last edited by LowR3V'in; 12-24-2018, 09:45 AM.

                Comment


                  #9
                  Originally posted by LowR3V'in View Post
                  you think he can send you that timing table?
                  my m30 picked up some hp after 5k with *2 more advance.
                  *2 more before 5k would lose like 7hp so it's a fine line.
                  looks like you're missing 20hp though

                  also i would go with a bigger cam it's not bad. i got a 293 or something like that
                  from cat cams. feels normal.
                  has alittle bit of cam sound in the exhaust but isn't felt driveabilty wise.
                  wish i went with their 300 for more revs.
                  yours is a turbo cam, it has wide lobe centres and small exhaust lobe so the overlap is relatively small. Also the M30 is a bigger engine which tames duration

                  04.041.012 from dbilas looks like a option https://dbilas-shop.com/en/engine-va...mshaft?c=12007
                  Last edited by digger; 12-24-2018, 04:45 PM.
                  89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                  new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                  Comment


                    #10
                    oh i see. :(

                    Comment


                      #11
                      I like to be at 12.5 or 12.3 for an NA street car, but I'm paranoid. Remember your O2 sensor is an average of all cyls. In general you tend to not see much of a difference in power being a little richer than needed, but it's safer. Timing is where you make your power. With that said, in my (limited) experience these motors will handle leaner conditions (~14.0 at WOT) in stock form without issue.

                      It really may be that the cam you have is not great, but I am not well informed on cam profiles for the M20 and what exact profile your 272 has. I agree with digger regarding cam timing--if you shaved the head you're advancing the cam timing as the chain length is shorter.

                      Regarding ignition timing, if your tuner at or over 30 degrees by 3-4k rpm I'm sure it's within the ball park. If not, I would add timing 2 degrees at a time until you stop picking up good power--unless you have some sick coated bearings and wanna run on the ragged edge with pump gas
                      '84 318i M10B18 147- Safari Beige
                      NA: 93whp/90ftlbs, MS2E w/ LC, 2-Step
                      Turbo: 221whp/214ftlbs, MS3x flex @ 17psi

                      Comment


                        #12
                        Did you set the cam timing by measuring the valve/cam lift? Maybe the cam timing is more advanced than optimum for top end power.

                        Comment


                          #13
                          I don't have an adjustable cam. It's set to factory cam settings.
                          Much wow
                          I hate 4 doors

                          Comment


                            #14
                            Originally posted by Cabriolet View Post
                            I don't have an adjustable cam. It's set to factory cam settings.
                            its probably a good investment, for example there are a few members who found that with the 284/272 cam that several degrees of retard made more power than as installed with factory marks. when i plotted out the cam it showed that the factory gear would mean the cam installs advanced alot so retarding the cam from the factory marks would mean it is installed as recommend by schrick
                            89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                            new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                            Comment


                              #15
                              Digger, thank you. i never knew that is was off by that much.
                              Much wow
                              I hate 4 doors

                              Comment

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