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What happened to my Motor?

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  • What happened to my Motor?

    As you all know, and by jasons reply and all, i blew the motor from getting in to boost and it started detonating, but the thing is, what exactly happened?
    Its a Stock ECU, with a Stock Turbo Swap, on 93 octane, stock boost, and 22 degrees of timing.

    What went wrong?
    I understand I have a higher compression ratio compared to a turbo motor, so the threshold for detonation is alot more likely, but why would getting in to boost for 20 seconds blow my motor, even though the charge air temps are a ton higher and get even higher as you stay in to boost, I dont think it should detonate at such low boost pressure with 93 fuel.
    If so then why did a link I read a while back say "300zx Turbos would frequently overheat there oil racing around a strip" which is a reason to get an oil cooler. That statement almost clearly states that when racing around a track, your basically pushing the motor, and of course getting in and out of boost, increaseing charge temps, so why dont those motors blow.

    I also understand that I do have a 200,000 mile long block, and there could be an infinite amount of variables, but I know something went wrong, because if the motor cant take STOCK boost for 20 seconds, then im sure as HELL it wont take 10 PSI of boost for the same amount of time.

    Any opinions without any hateful bashing? :?


    Compression Test:
    Cylinders, 1, 3, 4, 5, 6 got 160+ to 180+ PSI.
    Cylinder 2 got 40PSI, wet test brought it up to 70PSI.
    2 electrodes broke on 2 cylinders, one being the cylinder thats dead and the other being a still healthy cylinder.

    Video taken of when motor blew.
    Notice the motor shutting off after the run at the end of the video.
    http://video.google.com/videoplay?do...95553175&hl=en
    1SIKZ31 -86 SlickTop- R.I.P. 03/01/10 ... Parted out :-(
    ... New Project: LS1 Miata. Complete. 510whp. 2500lbs.
    1 Month Away from Rear Mount 76 --> 650-700whp.

  • #2
    wow, well, you were right you didnt wreck it.

    IMO 22* is too advanced on a boosted NA motor.

    Sounds like a head gasket or a melted piston.

    leakdown time
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

    Comment


    • #3
      maybe it was God's way of saying "don't go 135mph moron"....but yeah, i would have to agree with satan.

      440whp on pump fuel and the STOCK MAF

      Comment


      • #4
        Just re-read that you did the wet test and it bumped it up to 70 PSI. Yeah you melted a piston.

        Man, I told you 137 was too fast for you, doesnt quite say it huh?
        85 Z31 6.0 LSX turbo 766whp/792wtq
        04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

        Comment


        • #5
          Wow. Glad it was you and not me bro. I'll take this as a warning. Lately my clutch has been slipping so much that i haven't been able to really get on it, but it gave it a boot tonight and didn't notice any slip so maybe it's getting better. I'll have to remember this.

          When you guys talk about time on boost, what is an acceptable off-time between boost intervals? Say, maybe let off for 30 seconds THEN do another 15-20 on boost? Sound like a good plan? I have never driven over 125 and the only time i had it up to that was right after the turbo (didn't realize how fast i was going, car never pulled like that before. scared me shitless not gunna lie).

          I can't wait for April when the drags open...
          I'd love to do the SORC, but i think i'd need an intercooler to be safe in that event.
          Attached Files
          My beloved Z:1987 2+2 NA2T w/30a swap.
          My black sheep: 88ss parts car (pretty much stripped and gone)
          207k miles and counting. Turbo'd since 155k.

          Comment


          • #6
            I'm willing to bet that you tried to turn up the boost didn't you?
            Attached Files
            85 Z31 6.0 LSX turbo 766whp/792wtq
            04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

            Comment


            • #7
              I'd put at least $100 on it.

              Or the title to my car.
              It may not be a Z, but it's still got a turbo...

              Comment


              • #8
                Which year ecu are you running? Na or T?
                Attached Files

                Comment


                • #9
                  87 turbo ECU, 87 turbo swap.

                  Fucking sucks.
                  I melted a piston you think?
                  What should I adjust my timing to you guys think?
                  If I adjusted it 20 degrees BTDC will I lose low end torque, I cant believe I blew this motor, this motor was supposed to last for EVER, Im about to spend money I dont even have anymore, theres a 140,000 mile NA motor in the yard, also a 90,000 original mile turbo motor, Im probably getting the NA, because I absolutely do NOT want to get a 7.8 motor, I lost torque as it is.

                  After this swap, the freaking torque I had with my NA is GONE, literally, it is ABSOLUTELY unresponsive, if I would put it to perspective I personally think I lost 80% of my torque anything below 2000rpms or anything in vacuum, possibly caused by excess exhaust back pressure and excess restriction in the compressor for the motor...

                  No boost controller as of yet...
                  thats going in this week, will it be ok to run 10PSI of boost on this motor? Firehawk and im pretty sure others dont recomend it, but what could I lose if I did run 10 pounds? im going to make sure not to let it detonate this time around...
                  1SIKZ31 -86 SlickTop- R.I.P. 03/01/10 ... Parted out :-(
                  ... New Project: LS1 Miata. Complete. 510whp. 2500lbs.
                  1 Month Away from Rear Mount 76 --> 650-700whp.

                  Comment


                  • #10
                    1SIKZ31 wrote: Firehawk and im pretty sure others dont recomend it, but what could I lose if I did run 10 pounds? im going to make sure not to let it detonate this time around...
                    let me rephrase your statement for you so that you can understand it in no uncertain terms:

                    Someone with more experience than me thinks that i shouldn't run 10 lbs boost because i'm a boost noob and have no idea what compressed air is unless you're talking about the check valve on the back of my head.

                    In all seriousness, the fact that you blew up a motor for not listening to what other people with more experience recommended should indicate exactly what you have to lose for not listening. Either intercool your shit, or stay out of boost.

                    1SIKZ31 wrote:
                    what could I lose if I did run 10 pounds?
                    another motor.
                    Attached Files
                    Funny stories!

                    Comment


                    • #11
                      My 87t ecu was 15* stock setting.
                      imagination is a virtue

                      Comment


                      • #12
                        craZed wrote: My 87t ecu was 15* stock setting.
                        You sure? I thought 87 was 20* stock timing">? :?
                        1SIKZ31 -86 SlickTop- R.I.P. 03/01/10 ... Parted out :-(
                        ... New Project: LS1 Miata. Complete. 510whp. 2500lbs.
                        1 Month Away from Rear Mount 76 --> 650-700whp.

                        Comment


                        • #13
                          You're a fucking idiot, that's what happened.

                          I thought all ECU's were 20 degrees

                          Comment


                          • #14
                            Your problem was likely that you were running about 7 degrees more timing than you should have been with even a turbo compression motor. Like Crazed said the 87t ecu is probably set at 15 degrees and you had it set at 22. If anything you should have been running under 15 degrees to help make up for the higher compression ratio of your na motor. Did you try any different timing settings before deciding on 22?

                            Also, do you know the condition of the injectors that you are using?

                            Comment


                            • #15
                              You've got this

                              Did you try less timing to see if it liked it in boost? Or were you more concerned how it behaved down low? You cant do that when tunning via distributor.
                              Attached Files
                              imagination is a virtue

                              Comment

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