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  • Originally posted by ThankyouBedini View Post
    Spark gap.
    I did not remove the j-strap, but made the gap about 3 mm.
    Field effect over insulator surface between electrodes differ widely between types of spark plugs and does influence the optimum gap for each type and engine. So this was a good fine-tune!
    Last edited by Willem Coetzee; 04-09-2015, 03:22 PM.

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    • Originally posted by dowens View Post
      ...second plug is trailing for the exhaust on the rotoray... like the waste spark in a regular 4 stroke motor...
      Aha, thanks dowens! I see RX-8 has 4 coils - 1/spark plug. This is a blessing for Mika, since on the RX-8 coil-per-plug setup, then, it makes things a bit more straightforward.

      Would you agree that the first plug leading then would contribute the most to the actual fuel combustion and therefore need the higher priority for plasma ignition?
      Last edited by Willem Coetzee; 04-09-2015, 03:25 PM.

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      • Originally posted by Mika View Post
        I should be able to make the hv dc contact to the coil side (?) ... Should it have some special capacitors to keep up with the speed? I might take videos, dunno yet.
        Hi Mika,

        Your plasma system output should connect ON the spark plugs... see a few pages back how ThankyouBedini did his hv-wire-to-spark plug connections on his Toyota Land Cruiser... see also how Subadude in this thread's early pages did his plasma CDI hv-wire-to-spark plug connections.

        To help you look into capacitor charge speed and frequencies maybe maxc can suggest a good sight with a link to it?.

        We can all help to see whats possible and what is less possible if you can post the ratings of the following parts:

        - Inverter Output V & A
        - Capacitor V & uF
        - Bridge Rectifier Diode specs

        IF YOU KNOW HOW TO DO THE VIDEO POSTING, YOU WILL JUST LOVE TO POST YOUR SYSTEM WHEN ITS FINALLY WORKING!!!
        Last edited by Willem Coetzee; 04-09-2015, 03:54 PM.

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        • Mika, It should keep up I believe. It'd be like a Ford 2.3l that has 2 plugs a cylinder, shouldn't be a problem. Trial and error on if you need other caps, I think you'll be ok.I think there were old Datsuns that had 2 plugs a cylinder too. I'd like to get my hands on one of those motors, I think people would see different results as far as experimenting other fuels with 2 plugs,

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          • William, yeah. The first plug would be the one to start with. I had a 87 b12 motor rx-7,pretty cool little engine. I think the other plug is there cause it's not like a piston, but it still needs that exhaust spark is all.

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            • Yesterday was a great day!
              I popped 2 x 25 6A10 diodes in one lick! My big capacitor, 2000vdc 80 uf has some power! The diodes popped when I the output from the MOT was about 1800 vdc. I am now making the diode stings from the ignition coil and from the booster cap 50 x 6A10. I would like to know if there is a rule of thumb for booster cap value and diode string voltage?

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              • http://www.electronics2000.co.uk/cal...calculator.php http://www.rapidtables.com/calc/elec...Calculator.htm

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                • Then the booster cap diode string of 50 6A10 (50KV) broke after some HV testing with the 2000 vdc 80 uf cap.
                  I have 120 diodes left! Suggestions?

                  Maxc, Great links, Thank you very much.

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                  • Originally posted by ThankyouBedini View Post
                    Yesterday was a great day!
                    I popped 2 x 25 6A10 diodes in one lick! My big capacitor, 2000vdc 80 uf has some power! The diodes popped when I the output from the MOT was about 1800 vdc. I am now making the diode stings from the ignition coil and from the booster cap 50 x 6A10. I would like to know if there is a rule of thumb for booster cap value and diode string voltage?
                    That 80uf at 2kv is huge - do you have a cap around 20uf max? With my MOT charging a cap bank for the big booster cap blasts, the most voltage I was able to charge up to was about 1200v and I believe the capacitance was about 20uf at the upper end.

                    If I can even find some of the caps I used, I can see what they were then calculate the actual capacitance I had when putting them in series.
                    Last edited by Aaron Murakami; 04-10-2015, 10:59 PM.
                    Aaron Murakami





                    You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete. ― Richard Buckminster Fuller

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                    • Originally posted by Mika View Post
                      ...Do I need a cap for each plug or can I connect two plugs parallel in a same cap? I ordered two caps and hoped that's enough...
                      Hi Mika, sorry for not answering this - it is also important!

                      The "law" for COMPONENTS connected in PARALLEL to a Power Source state that the Volts will be the SAME for each component, BUT the Amps will DIVIDE according to each components RESISTANCE. How does this APPLY to your Rotory Plasma Ignition System?

                      (1) 1 Inverter connects to 1 Bridge Rectifier, and 2 Caps connected in parallel to that Bridge - so each Cap will get the SAME "charge" from the Inverter - no matter what they charge to.

                      (2) It looks like the RX-8 has ONE COIL per Spark Plug, so each individual Spark Plug Circuit is SERIES.

                      (3) The DIODE STRING of each Spark Plug in a Pair connects to one side of 1 Cap.

                      So if you did have a Capacitor per Spark Plug, they all would have charged to the SAME VOLTS, but would have each only got say a 1/4 of their "potential amps". Each spark plug then will have the same "amp potential" from its own cap.

                      With your current 1 Cap per 2 spark plugs, the cap will be at the SAME voltage for each spark plug, BUT output "amps" will SPLIT between the 2 spark plugs.

                      The real issue, and FIRST STEP is:

                      Please check what the HV OUTPUT POLARITY of each coil is - does each put out Negative or Positive HV?

                      Maybe all 4 coils (if I'm seeing correctly that they are 4 individual coils) might have the same HV Output Polarity - but its NOT so until you've check that it so.

                      You need to know which way round your Diode Strings need to go onto the Spark Plugs with your Caps, Bridge and Inverter orientated accordingly.

                      Many people have blown several sets of inverters, until they got at least the polarity orientations correctly matched and orientated to HV OUTPUT.

                      So discover what the HV Output Polarities are, FIRST.

                      Whether the spark plugs are fired HV negative or positive will dictate what the next step will be...
                      Last edited by Willem Coetzee; 04-13-2015, 12:42 AM.

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                      • Thanks again, William.

                        This is maybe a stupid question, but how do I determine which way the polarity is?

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                        • Originally posted by Mika View Post
                          Thanks again, William.

                          This is maybe a stupid question, but how do I determine which way the polarity is?
                          (1) Diode String Method: Negative is at the side of the line across the diode and positive is the side opposite - so if you put a diode string in series between spark plug and spark plug HT lead with diode (-) on HT lead and diode (+) on spark plug, the spark plug will fire if it has an HV NEGATIVE output; if it doesn't fire that way round but fires when you connect the diode string in series the other way round, the coil fires POSETIVE.

                          (2) Graphite Pencil Method: when the HT lead is held say 1/2 inch away from spark plug and the sharp point of a wooden pencil with graphite senter held halfway in between the HT lead connector and spark plug, the jumping spark will make feathery sparks in the direction of POSITIVE from NEGATIVE... so if it makes spark feathering the direction of the spark plug, the coil fires HV NEGATIVE, and if the spark feathers in the direction of the HT lead connector the coil fires HV POSITIVE.

                          There are other methods too, using maybe a compass or HV-instruments as well, but the above 2 might be the easiest.

                          I prefer the pencil metode myself, because with enough darkness I can see the feathering direction better, and don't blow a diode string by accident.

                          The amp-rating of the diodes you ordered is right, so if you use the diode string method, rather use 30-50 diodes in series in your test string, cause I got no clue with the Voltage Output of each of your HV coil secondaries are - you don't want to blow them by accident and then have to order them again.

                          Please check each coil - don't assume the polarities.
                          Last edited by Willem Coetzee; 04-13-2015, 09:04 AM.

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                          • Ok, thanks, I'll test that soon. These are the components I'm going to use. 200w 220v inverter, 50A 1000V bridge rectifier and two 450VAC 50/60Hz 4uF caps, maybe I'll order two more of those too. Four 100 ohm 100w power resistors also, but they have not yet arrived. Do these seem right kind of parts?

                            image.jpg

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                            • Hello!
                              I am looking for help so that I can understand the term "negative resistor" better.
                              Where and how is a negative resistance used?
                              How is a negative resistor made?
                              There is some talk about it here, but I just don't get it!
                              Thank you very much!
                              Last edited by ThankyouBedini; 04-15-2015, 11:24 AM.

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                              • Hey can you tell me will this plasma ignition fix misfires too, or will it only make a plasma spark "after" the original ignition parts get an ordinary spark through first? If you understand what I'm trying to say...

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