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  • Blown rings

    Well,

    a dear close friend of mine who is the lucky owner of a 2.3 M3 was speeding on the speedway when a giant blue/white smoke appeared from the tailpipe.
    The engine was rebuilt one and a half year ago with the engine block machined to 94mm and high compression ratio pistons which came from the manufacturer with the proper rings.
    Even if they where supposed to produce about 15bar, they never got over 14bar cause the valve pockets where deeper than stock.

    Today i examined the engine and there is no compression in the 2nd cylinder, plus oil in the water tank and water in the oil pan (almost half a liter comparing the levels of oil and water).
    We got also oil in the intake ducts.

    The strange thing is that the 2nd cylinder spark plug that was a platinum BMC appears to have the ground strap melted off.
    Obviously it is oil soaked.
    The other cylinders/spark plugs appear to be perfectly OK both plugs and compression.

    What can you tell me? What was the cause of the rings failure?
    Defective injector?
    Defective spark plug?
    power is nothing without drift

  • #2
    Have you inspected the rings?

    Sounds more like a failed piston and head gasket due to detonation. The melted spark plug is the give away.

    Steve
    Sport Evo No.47

    My Sport Evo Restoration

    Comment


    • #3
      Originally posted by stevesingo View Post
      Have you inspected the rings?

      Sounds more like a failed piston and head gasket due to detonation. The melted spark plug is the give away.

      Steve
      No i've not inspected the rings cause i'm not a mechanic and i can't open the entire engine.

      Detonation you say. MMMmmmmm.
      I've never listen to that M3 knocking...But it was alpha n equipped (no max automotive) and the ignition tables were changed...
      If it is a detonation issue why it affected only one cylinder and not the others?
      power is nothing without drift

      Comment


      • #4
        My guess would be detonation as well. You will probably find that the rings are ok once you open up the motor, but there will be other problems. A bad injector can lean out one cylinder. I have seen it many times and if the timing has been altered it can make the problem worse.
        Scott

        Comment


        • #5
          Originally posted by redrumM3 View Post
          My guess would be detonation as well. You will probably find that the rings are ok once you open up the motor, but there will be other problems. A bad injector can lean out one cylinder. I have seen it many times and if the timing has been altered it can make the problem worse.

          Thanks, i'll report :peekaboo:
          power is nothing without drift

          Comment


          • #6
            It sounds like severe detonation (melted plug electrode) leading to some or all of the following:

            blown head gasket (white smoke)
            cracked or melted head (white smoke and water in oil)
            broken ring lands (blue smoke and oil in the intake ducts)
            hole in piston (all of above)

            aren't platinum plugs bad for S14 engines? search on that too.
            high compression (what is your compression ratio?) requires high octane fuel.

            slight engine tuning off + lean condition + low octane fuel + part thottle at high rpms = lots of blue and white smoke.

            once the magic smoke comes out, you can't put it back in - you have to rebuild and replace thing$
            Last edited by JS154; 08-25-2009, 07:56 AM.
            sigpic
            2010 BMW Club Racing E30 M3 Touring Car Champion
            2011, 2013 SCCA Runoffs Super Touring Under 3.0L Bronze Medalist
            2011 SCCA Jim Fitzgerald Rookie of the Year
            2012 SCCA Northeast Divisional STU Champion
            2015 SCCA Runoffs STU Polesitter

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            • #7
              I'd like to see pics before giving my opinion, but for me oil mixing into water and vica versa generally means head gasket or head failure. That can be due to a few things, but I have also seen plugs melt due to coolant or oil getting into the cylinder.
              (This can cause a hike in CR on just one cylinder and cause det!)

              You'll only see for sure whats happened, including any det issues, once the head has been pulled and the pistons, valves, gasket, rings have all be examined. But I suspect once the head is off, it'll be obvious whats happened.
              Last edited by ShepsEVO3; 08-25-2009, 10:50 AM.
              E30 M3 Sport Evolution Black
              E30 M3 Sport Evolution Red
              E30 M3 Evo II Red
              E30 M3 Evo II Blue
              E30 M3 195hp Black
              E30 318 is White
              E30 318 is Red

              Comment


              • #8
                Thanks for the replies...
                Well yesterday i inspected the top of the 2nd piston through the spark plug duct...He got a nice hole of approximately 6-7mm right above the piston pin.
                One can actually see the piston pin.

                I've warned him to not modify the stock ign timing during A-N upgrade...But he did.

                Also, like i said in the forst post, this M3 wasn't equipped with the stock pistons,but the CR was 14bar.
                Now, in the 2nd cylinder, it is 1bar :hee:
                Maybe it was a wrong ignition timing map or the custom pistons that where bad for s14 applications.

                The timing map was, at least on the numbers, way less advanced with respect to stock, like the DTM a-n advance table which i got here, it was .pdf-ed to me by a german tuner.
                Last edited by france320isco; 08-25-2009, 07:36 PM.
                power is nothing without drift

                Comment


                • #9
                  As stated earlier, it may not be ing issue, but a blocked injector.

                  There have been a few instances where A/N equipped engines have detted themselves to death. Ign map should be tuned hand in hand with fuel. The A/N system evolved from the days of a stock ecu being used in motorsport as a facility to remove the AFM. These BMW M/S engines were mapped on the dyno and a specific ign map burnt on to the eprom. Most just fit the A/N system and leave the ign map as stock. Even on a stock engine this is bad. The A/N unit converts the TPS signal in to a signal the ECU will recognise as the AFM. The AFM is calibrated to give a linear out put in relation to load, air flow in relation to throttle position is non linear. People get around this by running rich (12-12.5:1AFR) in order to avoid det. This will cost power.

                  What was tghe compression ratio of the pistons, not the pressure?
                  What cams?
                  Do you have a screen shot of the ign map?

                  Steve

                  Steve
                  Sport Evo No.47

                  My Sport Evo Restoration

                  Comment


                  • #10
                    AFM signal ----> AFM transfer function ---->association between volts and load values (load values that are memorized in the ECU, from 1.00 to 5.4 ms).
                    This load value is divided by the injection constant and then multiplied by the A/F correction (one among the 256 values which are in the furl map, the one that corresponds to the that value of load and that value of RPM) to obtain the actual injector opening (ms).

                    In the case of the ign advance there is no multiplication, the value is chosen directly from load value (ms) and rpm value. And in the Bosch papers the load is always expressed in ms. It obviously could also be expressed in % AFM opening, but the ms representation make easier to get the actual inj timing in the fuel map.

                    Now...My friend (and me) doesn't have the A/N unit.
                    It is just a potentiometer for the load signal and a bosch ats for the air temperature.
                    Throttle Position Switch is stock.
                    We emulated the ECU with the "moates orstrich 2.0" till our cars were OK.
                    I only tuned the fuel map (partial and WOT) with a A/F ratio meter gauge and wide band sensor that i installed.
                    He tuned the advance too cause there was a sensible knocking on the M3 that was not present on mine (320is).
                    I suggested him to tune the potentiometer at an idle signal in Volts that was going to guarantee no knocking condition, it was sufficient to set it to 1.70V and tune the idle fuel map.
                    But he was stuck with the convintion that the pot, at idle, must have read 1.00V like the stock AFM.

                    I don't think the geometric CR was way above the stock M3 cause the pistons had valve pockets deeper than stock and only a little conic protrusion on the top.
                    I don't know the value exactly.

                    Cams perfectly stock.

                    I'm trying to attach a screenshot of the ign map.



                    And that was what was .pdf-ed to me from bosch which a lot of other papers with addresses, etc.



                    As far as i know the injector were cleaned with along mine 5 month ago or before.
                    Can a blocked injector produce such a mess??
                    Last edited by france320isco; 08-26-2009, 01:50 AM.
                    power is nothing without drift

                    Comment


                    • #11
                      Did you tune on a dyno/rollers and did you have knock listening device?



                      I'll look tonight for the stock ign tables.

                      Steve
                      Sport Evo No.47

                      My Sport Evo Restoration

                      Comment


                      • #12
                        Wow, ok, maybe it was det, but those ignition values don't look crazy atall.
                        E30 M3 Sport Evolution Black
                        E30 M3 Sport Evolution Red
                        E30 M3 Evo II Red
                        E30 M3 Evo II Blue
                        E30 M3 195hp Black
                        E30 318 is White
                        E30 318 is Red

                        Comment


                        • #13
                          195 engine


                          215 Engine


                          Stock 2.5


                          Steve
                          Sport Evo No.47

                          My Sport Evo Restoration

                          Comment


                          • #14
                            Is it possible he had a vacuum leak in just one cylinder that leaned out that cyl enough to cause detonation?
                            The day ain't over yet....

                            Comment


                            • #15
                              Originally posted by ///mike View Post
                              Is it possible he had a vacuum leak in just one cylinder that leaned out that cyl enough to cause detonation?
                              This is possible.. and also if the head gasket was leaking, this could also cause det.

                              But running a lean mixture will allow higher ignition values also without det. ie, say for EXAMPLE! you are running 15:1 AFR at full throttle 5000 rpm with 34/36 degrees advance, you will have max power with that timing with that AFR, but keep the timing and introduce more fuel and you will get det! Always best to set your afrs first then ignition timing. So running 13:1 AFR at WOT 5000 rpm you would need to retard the ignition timing.

                              Here is food for thought.... putting more fuel into the cylinder will raise the CR slightly! This will command less ignition for max power than a leaner mixture would.

                              Another comment above somewhere... running 12:1 AFR to supress an A/N car which is detting. Yes, this loses power also. But in reality what is happening, by richening up the fuel, you are changing the load signal, actually increasing the load signal will put in more fuel, but also it retards the ignition timing. When you lean it out, yes, the AFR's get leaner, but you will have more advance ignition also. Not wanting to throw spanners in the works here, but, imagine how much trouble you could be in if you fit a higher pressure FPR and larger injectors without modifying the ignition maps?

                              Obviously if you have hot combuston temps you need more fuel to help cool it and suppress detonation, but its not ideal in my opinion.

                              What a mess, hope the block and head survives.
                              E30 M3 Sport Evolution Black
                              E30 M3 Sport Evolution Red
                              E30 M3 Evo II Red
                              E30 M3 Evo II Blue
                              E30 M3 195hp Black
                              E30 318 is White
                              E30 318 is Red

                              Comment

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