Plasma Ignition | Plasma Jet Ignition

[Gary Hammond]

Hi Jeremiah,

The capacitor has to go in parallel with the plug, not in series.

[RB176]

Gary

First thanks for the help. Could you please explain what you mean by “In parallel.” Let me explain myself as well. What I did was put one of the ceramic capacitor wire ends, soldered to a washer under the spark plug and the other to positive end under the plug boot. This method was one I had seen on YouTube. Would a diode work, perhaps in a 10kv instead of a 20kv?

[Gary Hammond]

Hi Jeremiah,

I took your statement

inline with the spark plug

to mean in series between the coil and plug so that all the current had to pass through the capacitor on the way to the plug. This would greatly limit the spark output.

What I did was put one of the ceramic capacitor wire ends, soldered to a washer under the spark plug and the other to positive end under the plug boot. This method was one I had seen on YouTube.

This is putting the capacitor "in parallel" with the plug and is the correct way to do it.

You may have used a capacitor with too low of a voltage rating which allows it to break down internally. Or it may even be shorting out externally if the wire end attached to the plug boot is too close to the plug base. Or the capacitance may be either too much or too little for the desired effect with the particular coil you are using. And adding an extra washer under the spark plug gasket will raise the plug in the combustion chamber causing a shrouding effect which is detrimental to the combustion process. Without being there, it's had for me to troubleshoot exactly what's happening.

Have you considered just using a high performance coil instead of the stock Kohler coil?

Would a diode work, perhaps in a 10kv instead of a 20kv?

It's my understanding that a diode works only in conjunction with a capacitor discharge box supplying power to the primary. Aaron ??

[Aaron Murakami]

I was wondering if someone could help me out with creating better spark with a Typical battery points and condenser/capacitor ignition system on a old Wheel Horse lawn tractor http://gardentractorpullingtips.com/animate/ign1ani.gif
I do not want to put a msd box on it because that system would probably cost me more than the tractor lol. Could I use a 20kv diode like Peter did in the video on page 1 of this thread. Thank you Jeremiah

Gary is correct, you need a capacitive discharge system.

$115 USD https://www.speedwaymotors.com/Proco...Box,19685.html I've never tested that but it is a low cost option.

I have had 100% success with this unit, $152 USD https://www.amazon.com/gp/product/B0...SIN=B001O28622

[Aaron Murakami]

The diode goes from the + of the ignition coil where the CDI is connected - that connection from a CDI or MSD to the + of ignition coil is connected to the + of the capacitor in those units. Diode goes from there to the top of each spark plug - I'd use 1 diode per cylinder. When the spark is made, the capacitor will then discharge directly over the spark plug gap.

[RB176]

Some good information there. Gary I actually do have an upgraded Bosch coil I bought used which is a 30kv. And as far as plug depth I took the compression washer off and used another washer that was the same thickness just bigger around which gave me enough space to soldier on the capacitor and also I soldiered the other end to the wire crimp under the plug boot. The one thing I can say is if were to use a capacitor between the coil and the boot the capacitor wires are very thin and probably not with stand the vibration.

[Gary Hammond]

Hi Jeremiah,

Here's a video I found that shows the proper values for a peaking cap and how to wire it. Enjoy.

[RB176]

This video is basically the same setup that I tried. I used a 30kv and also 3 15kv capacitors in series all with the same results. Gary you mentioned maybe trying a bigger cap, what size would you recommend?

[Gary Hammond]

Hi Jeremiah,

Please understand that I have not worked with peaking caps. All I know about them is based on reading literature and watching videos.

My experience is with switching from points triggering to solid state triggering for conventional ignition set ups on small engines. I also have installed an MSD 6A ignition box, triggered by a Compu-fire hall effect trigger device, driving an MSD Blaster 2 coil on the modified VW engine installed in my Bradley GT kit car. I'm running a .060" or .070" plug gap and expensive plug wires which gives me a very hot ignition with easy starting and no misfire to the engine red line of 6000 RPM.

I have ordered, and am going to install, high voltage diodes as well so I can get the plasma effect. Then I'm going to experiment with water vapor and lean burn on this engine. It also has dash adjustable electronic fuel injection running in open loop which should work great for experimentation.

As for the value of the peaking cap, it's my understanding that too much capacitance will take too long to fill the cap at high RPMs and you will lose the effect and may get misfiring. So whatever you were using, I would try a capacitor with about half that value but still rated for 20,000 to 30,000 volts. If I were doing it I would probably start at 50pF and go up or down from there.

[RB176]

Again thanks

The capacitors I tried were 15kv 2200pf and a 30kv 1000pf. I’ll try some different pf caps and see what happens.

[RB176]

30kv 102. 15kv 222

[Faraday88]

30kv 102. 15kv 222

You can use Home made Glass Layden jars for the peaking Capacitor discharge best and cheap one after all!
Rgds,
Faraday88.

[ahGM]

Hi , Please explain about the Glass Layden.Thank you

[Bradley Malone]

A leyden jar is a homade capacitor that can withstand high voltage. If you put liquid into a glass bottle and submerge it half way into a bucket of water ....the water in the bottle is one capacitor plate and the water in the bucket is the other capacitive plate. As long as you don't go above a voltage that can not jump through the glass "dielectric" it is a capacitive system. You can use many bottles with jumpers between the inner water to raise the capacitance. If you think of how much voltage it would take to "jump" from the water inside to bottle to the water outside the bottle it would take a very very high voltage. So it is a very cheap and effective way of making high voltage capacitors with some beer bottles water and a bucket....or many other variations.

[Faraday88]

Hi , Please explain about the Glass Layden.Thank you

Hi,
For our purpose here, you need not actually have a classical Layden jar set up..meaning bottel size.. you may use miniature size Plastic/HDPE photographic film boxes and make Layden jar as Bradley malone described in the post.
Ideally, the inside of the boxes you may use brine water and aluminium foil for the outside plate of the Capacitor (Layden jar) that it forms.
Rgds,
Faraday88.