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  • Ignition Questions and Trickery

    Howdy,

    Well its late at night and I can't sleep so I dreamed this up. I am unhappy with the waste spark setup on my Turbo6 with its reverse polarity sparkplugs. As such I'd really like to get the plug polarity flipped around on half of them. Looking over my wiring diagrams it looks like the spades on the Ignition Control Module (ICM) for each of the GM twin tower coils are nothing more than the primary side of the coil so it should be possible to trigger other coils using this input per my theory. Would it be possible for the ICM to run 2 separate coils off of 1 input or would that burn the ICM up? If so I have the MSD adapter terminal blocks so that I could put a DIS-4 on it but those boxes have questionable reliability from what I have heard, so I was thinking running some "dumb" Coil On/Near Plug (CO/NP) being triggered by ICM.

    The second question is a sort of tag along with potentially using a triplet of aftermarket boxes to drive the pairs of coils or would that over tax and burn up the boxes?

    Thanks,
    Central TEXAS Sleeper
    USAF Physicist

    ROA# 9790

  • #2
    Re: Ignition Questions and Trickery

    This would double the current load on the control unit and could very well damage it depending on what coils you used. You might be able to use Ford COPs wired in series instead of parallel, as these don't put a very large load and the coils can be fired that way.

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    • #3
      Re: Ignition Questions and Trickery

      I'm really just after the reversing of the polarity and keeping the same ignition power. Reversing the plug polarity has been shown to add measurable horsepower on the Turbo6 and I'm getting sick of everyone claiming to be "just about" to make an LS1 sequential ignition system for the GM V6 ignition system. I wonder how much power the LX5 "Shortstar" V6 coils pull.
      Central TEXAS Sleeper
      USAF Physicist

      ROA# 9790

      Comment


      • #4
        Re: Ignition Questions and Trickery

        If they're like other LSx coils, they'll have built in ignition drivers. You'd need to make some sort of interface circuit to drive them from a DIS module.

        Comment


        • #5
          Re: Ignition Questions and Trickery

          What kind of interface are we talking about for LS1 coils? What kind of signal are the coils looking for (voltage bias, frequency....)? I have a hall effect cam trigger and a crank sensor that puts out a dual outputs for the outer 18x ring and the inner 3x varied slot ring coming in as well as the ECM inputs for the ICM.

          The LX5 is the Northstar derived 3.5L DOHC V6 used in the Intrique and Aurora, I have a feeling it has a built in module as well since it has a huge plug on the end of the coil block.
          Central TEXAS Sleeper
          USAF Physicist

          ROA# 9790

          Comment


          • #6
            Re: Ignition Questions and Trickery

            LSx coils have a connection to the ECU that starts the coil charging when you apply 5 volts to it, and it stops charging and fires the coil when you drop the voltage back to zero.

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            • #7
              Re: Ignition Questions and Trickery

              Thats sounds like putting a voltage regulator inline to drop the normally 12V charging signal off of the ICM down to 5V then trip it when the coil signal goes open.... why is this taking people so long to rig up????
              Central TEXAS Sleeper
              USAF Physicist

              ROA# 9790

              Comment


              • #8
                Re: Ignition Questions and Trickery

                Originally posted by CTX-SLPR
                why is this taking people so long to rig up????
                Honestly? because it's a waste of time if the goal is "engine that runs good"
                www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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                • #9
                  Re: Ignition Questions and Trickery

                  Well they reverse polarity spark plugs are a proven power consumer on the Turbo6. I've honestly not seen any Megasquirt run Turbo6's, so it might be an engine specific problem. All the other systems I know of either use a distributor or reuse the stock waste spark system except for the Motec guys (of which there are only a handful). The distributor guys have been measuring around 20hp difference than the same engine running a DIS wasted spark system on 600-700hp range engines. This has largely been attributed to the reversed polarity of half the plugs. I doubt this is a problem on other engines since the Electromotive guys have been running this setup for a long time and I've talked to other turbocharged engine guys and they have not had problems with the DIS waste spark system.

                  The Electronics Engineer wife and I have been messing around with this tonight on designing the basics of a conversion system to get the LS1 style coils to run off of the ICM outputs and have started sketching up a system to make it full sequential. Out of curiousity, what is the primary resistance on a typical "dumb"CO/NP coil and what is the resistance on a low impedence injector?

                  Thanks,
                  Central TEXAS Sleeper
                  USAF Physicist

                  ROA# 9790

                  Comment


                  • #10
                    Re: Ignition Questions and Trickery

                    sorry, I just don't believe anyone who says the polarity of the plugs can gain or lose horsepower.
                    www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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                    • #11
                      Re: Ignition Questions and Trickery

                      Its a prooven fact on the Turbo6, I won't make the generality any farther than that but there is power from going from the DIS to a distributor so its either in the waste spark or the reverse polarity plugs. This is on engines run with a FAST system as well as stock with no other changes and proper tunes. A guy built himself a system using a pair of the ignition modules and coils and tied the second tower to the block and got almost identical results to a distributor system still running the waste spark system so I'm inclined to believe that its in the plug polarity.

                      Would you happen to know the dwell times on the GM DIS twin tower coils?

                      Thanks,
                      Central TEXAS Sleeper
                      USAF Physicist

                      ROA# 9790

                      Comment


                      • #12
                        Re: Ignition Questions and Trickery

                        The GM DIS coils are popular, but when I "select" dwell times, I use a scope to measure saturation so I know what the limit is.

                        Back to this claim of power by changing polarity - you say "20 hp" but what does that mean? is this a 200hp engine, or a 900hp engine, etc? It's totally retarded to claim a power gain and not know the percentage of total power output. This is like the guy who claims Sequential EFI tuning picks up 20hp, except he failed to mention that it was a .007% gain in power (on a 1600hp engine) - in other words, dyno margin of error.

                        More details are warranted. Also, I'm not sure where you get that since I like megasquirt I can't know anything about other systems - I have somewhere around 100 FAST tunes under my belt, including a ton of Turbo 6 engines in the 800-1200hp range. Hence, I call BS when some "mad scientist" makes claims that don't seem to make any sense. A plug either lights the fire in the combustion chamber, or it doesn't. Period.
                        www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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                        • #13
                          Re: Ignition Questions and Trickery

                          Time out for a second Scott, I don't know where I've stepped on your toes but lets take a beather for a moment and take this out of the realm of me vs you or anything like that. I do think that you are a 1 horse show with only doing the MS EMS systems nor am I taking it personally that you are disagreeing with me here.

                          Originally posted by CTX-SLPR
                          The distributor guys have been measuring around 20hp difference than the same engine running a DIS wasted spark system on 600-700hp range engines. This has largely been attributed to the reversed polarity of half the plugs.
                          These are not my measurements, they are some other peoples including the series champion in the Turbo Stock Motor series Jason Cramer (Race Jace). This has been a reoccurring situation with distributor guys picking up power and no one agreeing how its coming. Some have suggested that its the wasted spark lighting off unburned mixture in the dead cylinders due to the open chamber design, others the reversed polarity spark plugs, still others have suggested that its the coils running out of juice at the top end under high boost conditions. I tend to discount that last one since the V8's and the 3800's running the same coils don't encounter the same issues so that leave the first 2. Since the switch to a waste spark setup on forward firing plugs seems to create the same gains as a full sequential setup on a distributor I'm inclined to think its the plug polarity.

                          I'd love to be able to run LS2 coils in sequential setup but I'm not to that point on the electrical engineering and I'm sticking with the EMS I'm currently planning on using, which by the way I got the harness 90% done last night.
                          Central TEXAS Sleeper
                          USAF Physicist

                          ROA# 9790

                          Comment


                          • #14
                            Re: Ignition Questions and Trickery

                            is there a thread somewhere I can go read about this testing?

                            has the guy considered maybe the two ignition systems are draining more power from the alternator? what other differences can there be? is he sure he has the right heat range of plugs, etc.? and if it's misfiring, he should see that real quick on O2 inputs... there is just no sense in claiming a certain plug type makes more power, improves drivability, etc. It drives me nuts when I hear "yeah, those new MSD coils made my drivability better" - so you get where I am coming from.
                            www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

                            Comment


                            • #15
                              Re: Ignition Questions and Trickery

                              I understand completely, especially since this is a single engine design occurance because I've questioned others using the DIS twin tower coils about problems and there have been 0 problems. I'll dig up the threads when I get home on this but it's interesting that GM for the Indy program used the DIS Type I (Magnavox block coils) rather than a distributor though they had the closed chamber Stage II heads.

                              Eitherway I'd like to make an adapter box to run the LS2 coils on my engine and right now the major stumbling block is that I think the DIS Type II coils use an ~3ms dwell while the LS2 truck coils use ~5ms dwell time so I'm looking for a way to either add something inline to increase the dwell time by using resistor and capacitor then a voltage regulator but I'm also bugging the HPTuners guys on adding the dwell table into the tuner.
                              Central TEXAS Sleeper
                              USAF Physicist

                              ROA# 9790

                              Comment

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