Testing a method to increase spark current

Discussion in 'Performance Mods' started by jaguar, Nov 19, 2015.

  1. jaguar

    jaguar Well-Known Member

    I got the itch to do my own testing after watching a video of someone testing increased spark with 500pf of capacitance in parallel with a spark plug; https://www.youtube.com/watch?v=tdaN4z8LuQg

    Here are my results with three 680pf capacitors in series (each rated 6300 volts) in parallel with a non-resistive spark plug gapped at .025” (.65mm).
    Tests were done with spark plug in open air at sea level using my CDI tester.

    with KX250F ignition coil (#F6T563) (.3 ohm primary, 13.8K secondary coil resistance)
    It didn't increase the spark power but it stabilized spark timing which is important.
    Normally there are many stray spark occurrences that are as much as 10 degrees retarded. Those events would cause a reduction in engine power since timing is critical. With the capacitance the sparks all happened at the same timing without any straying. You could see that at the spark also. Without the capacitance the sparks moved around, but with it they stayed at the same place.

    KX65 ignition coil (.4 ohm primary, 5.5K secondary coil resistance)
    It increased spark power so that the spark changed from thin purple to thick white.
    But it allowed the normal stray spark occurrences.

    Kawasaki KDX220 (#1G 3960) ignition coil (.2 ohm primary, 11.1K secondary resistance)
    Pretty much the same results as the KX65 coil.

    None of these coils in combination with parallel plug capacitance worked with my Suzuki AX100 which has 150psi cranking compression. I couldn't get the engine started. All I can assume is that the capacitors lower spark plug voltage so that no spark can occur inside the combustion chamber. (cylinder pressure requires around 3 times as much voltage for a spark to occur*) I even tried it with four capacitors to lower the capacitance to 175pf but without success.

    * a flat surface spark gap needs 3Kv for a spark to occur at sea level in open air whereas at 145psi 9Kv is needed.
    Last edited: Nov 23, 2015
    mikedabomb likes this.

  2. lazylightning@mail.r

    lazylightning@mail.r Active Member

    Hi Jaguar!

    Wow! That looks really interesting! I think that high performance could really be boosted with a high power plasma spark! I tried reading up on it and I discovered that high compression engines (10:1 compression or more) need really high voltage sparks. I had a Pontiac 400 once with 10.5:1 compression, increased cam-valve duration, super strong double chain timing chain, cold forged pistons, high out put oil pump, balanced crankshaft, stellite exhaust valves seats and stainless valves. The shop that built it for me was really pro with a great reputation. The guy told me to buy a Mallory 40,000 volt high performance ignition coil and of course a dual contact ignition distributor. Upon reading up on this subject now, I discovered that alot of high performance motorcycle ignition coils have 40,000+ volt discharge. I even found a manufacturer that makes 80,000 volt racing coils and they swear it makes a difference. On one site I found out that each and every coil has it's own leakage inductance rating and that you need to tailor it all around your build for the best results. There may also be some need to consider different sparking settings, longer duration vs short multiple spark firing.

    What I can't find so far, is a forum where a group discusses making do it yourself ignition coils for small engines. It shouldn't really be any harder than winding any transformer though. I think this project would require a custom approach. Maybe something would have to be engineered from scratch. Part of the question might be in having enough magneto power. Maybe this is where those magneto kits would come in handy with the extra power input.

    I recall reading up on do it yourself x-ray devices. They were taking two regular automobile ignition coils and plugging 120 volts into the charge up side. The output of course would be like ten times more than it would compared to a 12 volt car system. The output (sparking side) would go directly into the charge up side of the second ignition coil and thus the output of the second coil would be something like a million volts or more. This super high voltage was not grounded, but just connected to a vacuum tube with a peice of aluminum foil wrapped around the outside of it (but not close to the contact). X-rays strong enough to take pictures of bones, things in bags and so on were emitted. So where there's a will, there's a way! Maybe a special little booster coil could be designed that would take the high voltage output of our standard coil and make it five times stronger along the way? Plus capacitors? I've seen such booster coils offered on the automotive performance market.

  3. jaguar

    jaguar Well-Known Member

    well it would take a special high output coil to make enough power to use with a capacitor.
    tell me the site of the place that makes high performance coils for motorcycles.
  4. lazylightning@mail.r

    lazylightning@mail.r Active Member

  5. jaguar

    jaguar Well-Known Member

    here's some good info from http://www.motorcycleproject.com/text/high_perf_ignition_coils.html

    How Does a High Performance Ignition Coil Help Performance?
    A high performance ignition coil helps engine performance four important ways. First, the higher voltage allows for a larger spark plug gap, which results in a more robust initial flame kernal at the start of combustion. The result is a real-world engine torque increase. Second, having more voltage on tap means the voltage required to bridge the spark plug gap gets there faster, leaving less time for voltage diversion through the spark plug's inevitable carbon deposits. Third, the higher voltage potential creates a stronger "push" on the electrical stream to the plug, resulting in increased electrical current, i.e. more energy, more snap. Fourth, with more voltage available, there is more in reserve for non-standard situations such as two-up plus camping gear and trailer while going uphill on poor fuel on a hot day with too low tire pressures and a 20 mph headwind. :)

    Why So Much Voltage?
    This last thought brings us to the subject of how much voltage is commonly used by the spark plug. The fact is the voltage needed to bridge the plug's gap is not constant but always changing, and is nowhere near the level of the ignition coil's voltage potential. That is, a 30,000 volt ignition coil virtually never fires its spark plug at 30,000 volts, but more often at 5,000-15,000. How can this be, and why the extra then? When a spark plug is about to fire, what happens is the air inside its gap is of course not conductive and must be made so. It is actually temporarily made conductive, and this is called by a fancy name that has to do with atoms and such, "ionization.". It simply means that the air is prepared to flow electricity. A pretty mysterious thing, this. Think of it as the air molecules getting so heated and excited by the rapidly building plug voltage that the result is voltage can flow through this agitated air to jump the plug's gap. How much voltage is required to make ionization happen depends on several things ranging from the amount of cylinder compression to how worn the plug's electrodes are. But in round numbers you will be safe to think 5,000 volts at idle. As soon as the throttle is used however this goes up, and if the transmission is put into gear then load comes into the picture and the requirement goes up even more. So let's settle on about 15,000 volts for a bike in a state of cruise. Now go uphill and the requirement increases. Be in too high a gear for conditions and it increases. Yank the throttle open hard and it increaes. Go downhill and it decreases, downshift to a lower geat and it decreases. So the actual voltage is all over the place while the bike is being ridden, and higher voltage ensures there is always enough and that it gets there fast.

    What About Modern Bikes?
    An interesting thing has happened in recent years. You now see high performance ignition coils being found on, and sold for use on, only older, non-fuel injected vehicles. Vintage carbed bikes, in other words. High performance ignition coils are not needed on modern vehicles, not because the factories have started putting better coils on their bikes, but because they are fuel injected. The main reason vintage vehicles benefit so much from better ignition coils is because their carburetion is heavily emissions spec and full of other fuel/air compromises that make carburetion far less than perfect. What a high output coil does in these cases is compensate by its superior ability to ignite less than perfect mixtures. That's right. Better ignition coils make up for poorer carburetion. It also works in reverse. Better carburetion makes fewer demands on an engine's ignition system (this is in fact one of the benefits of a properly rebuilt carburetor -- not only is carburetion good, combustion improves through more efficient ignition utilization too, as a by-product). The thing is, today's engines carburet so flawlessly due to fuel injection that mongo coils are no longer needed.

    The Stick Coil Controversy
    In fact, manufacturers are today installing weaker ignition coils than ever before in powersports history, not stronger ones. What do you think "stick" coils, or as they are known in the auto world, "coil over plug" ignition coils are? Wimpy, minimalist, cost-down ignition coils, that's what! Seriously. And in their usual way, the Internet forums have everyone convinced retrofitting stick coils to vintage bikes is an advantage! But it is far from that, a disadvantage in fact. Modern engines get by with weaker ignition coils because fueling is now virtually spot-on and no longer compromised. Stronger coils are not necessary.
  6. jaguar

    jaguar Well-Known Member

  7. jaguar

    jaguar Well-Known Member

    from http://www.aquapulser.com/performance_ignition/faq.html

    What is a plasma spark and how does it differ from a standard ignition spark?

    By definition all sparks comprise of an ionized channel called plasma. However the plasma channel generated by a conventional ignition coil and CDI driven coils, even high performance modules such as MSD, is extremely low in net energy content, primarily due to losses owing to the high resistance of the thin wires of the secondary side of the ignition coil. A standard ignition spark is characterized by high voltage with peak current not exceeding 200 hundred milliamps.

    A plasma spark as referred to on the internet or by ignition engineers means a high voltage ignition spark with a very large ignition kernel with peak currents exceeding 20 to 30 amps. The net energy output of a plasma spark is several 100s of times greater than a conventional spark.

    A standard ignition spark is barely visible and generates little to no photonic energy. A plasma spark is characterized not only by a massive ignition kernel but with liberation of high energy photons as well. In addition, owing to the extremely short duration of the high current 'pulse' which breaks down a relatively large quantity of the surrounding gases, an audible shockwave is unleashed as the gases are 'cracked' which is the same physical phenomenon as a clap of lightning causing thunder.

    The air fuel mix inside the combustion chamber is ignited when an ionized plasma channel traces a path across the spark plug gap. The spark is the 'hottest' as it breaks across the air gap to the other electrode and the fuel is ignited ONLY during this initial break down phase which lasts less than 100 microseconds.

    As soon as the spark reaches the ground electrode the subsequent tail end of the spark is of little to no use in the combustion process and is wasted energy. Once the fuel ignites the efficiency or net energy content of the burn is determined by how fast the flame front expands and how much of the fuel is fully combusted. Full combustion results in a greater amount of heat energy liberated which is then converted to mechanical work by the piston.

    The rate at which flame front expands is determined by the amount of energy delivered in the first few microseconds as the gap breaks down. A stronger energetic pulse results in a much larger faster flame front while a weak spark results in a flame front that is lower and in some cases only partially ignited.

    A weak spark from a conventional ignition coil will ignite the fuel however, the owing to the low energy content of the spark, the combustion is usually partial with increased emissions, lower power and increased fuel consumption. MSD was founded in 1970 with a simple solution of repeating the low energy spark multiple times to increase combustion efficiency using a CDI to drive the ignition coil. The working theory being that the more weak sparks there are the greater the likelihood it will burn all of the fuel. The multiple spark discharge technology became the name of the company MSD.

    Multiple spark discharge not only increases plug wear it offers only a partial solution as all MSD boxes even the latest ones with �Digital� technology generate multiple sparks only at 3000 RPM and below. Once the RPM increases above 3000, all MSD boxes digital or otherwise generate a single low current high voltage spark for every ignition cycle.

    This is ironic as the MSD box is nothing more than a conventional CDI above 3000 RPM yet the brand has a near virtual monopoly when it comes to racing. As the engine speed increases above 3000RPM, complete combustion becomes near impossible as less fuel is combusted during each ignition cycle. This is one of the main reasons why power and torque significantly starts dropping at higher and higher RPMs.

    High energy Pulsed Direct Current Ignition works the exact opposite of MSD. Instead of multiple weak sparks, the SparkAmp ignition module discharges a single high energy pulse of DC current across the spark gap along with the high voltage spark from the ignition coil. This secondary current source dramatically expands the size of the ignition kernel of the conventional spark from a standard ignition coil. The surge current exceeds 100 amps during the initial break down phase which is responsible for igniting the fuel. As the capacitor discharges all of its energy in less than a fraction of the second, it also emits high energy photons along with a shock wave which causes the flame front to expand much faster than a conventional spark induced flame front.

    Unlike MSD (which is actually only MSD up to 3000 RPM), the SparkAmp ignition module generates a high energy plasma spark with an ignition kernel almost 100 times larger than a normal spark even at 16000+ RPM. This is the reason why dyno tests of the SparkAmp ignition module show consistent gains in horsepower and torque at higher RPMs, as more fuel is ignited consistently and reliably in a shorter amount of time.

    Can the SparkAmp unit be used on a small engine such as a motor bike or outboard motor?

    Yes. The SparkAmp unit can be used in inline mode for any single cylinder or V twin engine. You will require non resistor plugs and a copper core cable to connect from plasma output to the spark plug. Refer to the SparkAmp Manual
  8. jaguar

    jaguar Well-Known Member

    One main problem is that this ignition system gets weaker as RPM rises because there is less time to charge the main capacitor inside the CDI. (see blue graph) If a battery driven voltage multiplier would supply the 1uf capacitor continually with 180 volts then we could gain back the spark power that is being lost. I figure increasing the cap voltage from 150 to 180 at 6000 RPM gives a 20% gain.
    For my Suzuki 100 at 9500 RPM the gain in spark power would be a whopping 64%.
  9. lazylightning@mail.r

    lazylightning@mail.r Active Member

    I remember those electrical upgrade systems for our China bike engines have a setup to charge a battery as well as a secondary coil to pick up more juice from the spinning magnet. I think it may be neccesary to have the extra juice to do this. If it will need more, then a small generator will have to be added. In that case it would be good to have the option to switch between standard spark system and enhanced spark system for when you need more power.

    As I understand, this system just enhances the standard ignition coil by sending high amp/high energy DC current in at the same time the ignition coil is sparking."High energy Pulsed Direct Current Ignition" So this is the better one, that we need? In this case we wouldn't have to wind a special coil. But these aquapulser modules are quite expensive. We will have to make something like it with our own hands.

    Here's a rundown of about everything, including the capacitors on the sparkplug. It may not be objective or include evrything though. http://www.knite.com/tech/comparison.aspx

    This seems really interesting, I'm sure the patents show for reference on this page could really useful: http://www.hho4free.com/sparkplugs.htm

    These papers may be of interest: https://repositories.lib.utexas.edu/bitstream/handle/2152/30893/PR_172.pdf?sequence=1



    I think this one is about capacitors being in paralell with the plug. https://pulstar.com/technology/patented-capacitor/
  10. lazylightning@mail.r

    lazylightning@mail.r Active Member

  11. lazylightning@mail.r

    lazylightning@mail.r Active Member

  12. lazylightning@mail.r

    lazylightning@mail.r Active Member

  13. jaguar

    jaguar Well-Known Member

    from that first link you gave:

    A small peaking capacitor mounted next to the plug can be added to a conventional ignition system as an aftermarket application. This will deliver more energy during the initial breakdown phase of the discharge and a larger spark formation. This increases ignition system performance for a small increase in cost.

    At low load, however, when more potent ignition is needed to ignite the air/fuel mixture, the system shows little improvement, because it produces a low breakdown voltage. At high load, when enhanced ignition is not usually required, the capacitor is charged to high voltage and delivers significant unnecessary energy. In addition, the peaking capacitor causes rapid electrode wear, due to the high currents passing through a stationary arc.
  14. jaguar

    jaguar Well-Known Member

    I disagree with the previous statements concerning low and high load needs. I agree that plasma spark may not produce great power increases but every little improvement helps add to a good package.
    Retesting today with 6 capacitors in series for a equivalent capacitance of 113pf, and a spark gap of 1.8mm (to simulate being inside the engine), the spark would only happen from 1300 to 9300 RPM. So I am ordering smaller capacitors to test equivalent values of 73pf and 50pf to see what happens.
  15. lazylightning@mail.r

    lazylightning@mail.r Active Member

    I was thinking the same thing. And what did they mean by too much energy discharge at higher loads(rpm's?)? I cant imagine that there would be too much discharge at any point.
  16. jaguar

    jaguar Well-Known Member

    "At low load, however, when more potent ignition is needed to ignite the air/fuel mixture, the system shows little improvement, because it produces a low breakdown voltage. At high load, when enhanced ignition is not usually required, the capacitor is charged to high voltage and delivers significant unnecessary energy."

    yeah low load is not that important because that is when you are off the throttle or just idling but it doesn't change the breakdown voltage. That voltage needed to spark the gap is more dependent on the compression which is more when you are on the gas within the expansion chambers powerband. The voltage from the high voltage coil is low at real low and real high RPM, not anything dependent on the load.
    And I don't see why they think a fatter spark is inconsequential at high load. Possibly with a denser mixture it takes less spark power to ignite it, but still the speed of the flame front increases or decreases speed with the strength of the spark. Flame front speed needs to be as fast as possible when performance is important. Of course then that may require retarding the ignition to have the peak combustion pressure happen at the same time of each engine cycle.
  17. jaguar

    jaguar Well-Known Member

    I had to keep lowering the capacitance trying to find what works. Even down to 50pf it still lowered the spark voltage too low to run my Suzuki 100 although it seemed to work on my bench tester with the spark gap set at 1.8mm
  18. HeadSmess

    HeadSmess Well-Known Member

  19. lazylightning@mail.r

    lazylightning@mail.r Active Member

  20. jaguar

    jaguar Well-Known Member