Spark plugs

kjjohn · Tue Oct 20, 2009 6:53 pm

I am thinking of wiring up 5 small spark plugs in a metal chamber for my hybrid. I am going to use the spark plug electrode as the HV wire, and the chamber itself as the return. How do I insert a spark plug through the side of the chamber? I am thinking that I will just use a tap, but I want to make sure I do it right. I have never done this before. Do I have to drill a hole that diameter into the chamber first, then use the tap?

D_Hall · Tue Oct 20, 2009 8:01 pm

1) Select your spark plug.
2) Find out what threads are on said spark plug.
3) Buy a tap for those threads.
4) Buy the proper sized pilot drill for that tap.
5) Use drill/tap as appropriate.

Really, it's not that damned hard. You just have to buy the right tap and drill the right sized hole.

kjjohn · Tue Oct 20, 2009 8:04 pm

Thanks, sounds pretty easy.

Moonbogg · Tue Oct 20, 2009 8:19 pm

When you buy taps at home depot or Lowes or wherever, they are available in "kits' that come with the needed drill bit as well as the tap.

jimmy101 · Wed Oct 21, 2009 9:21 am

kjjohn wrote:I am thinking of wiring up 5 small spark plugs in a metal chamber for my hybrid. I am going to use the spark plug electrode as the HV wire, and the chamber itself as the return. How do I insert a spark plug through the side of the chamber? I am thinking that I will just use a tap, but I want to make sure I do it right. I have never done this before. Do I have to drill a hole that diameter into the chamber first, then use the tap?

That means you will need five separate spark sources.

If all the gaps use the chamber as the return then the gaps are in parallel. A single spark generator won't work with gaps in parallel since only one of the gaps will actually spark.

Technician1002 · Wed Oct 21, 2009 11:23 am

jimmy101 wrote: That means you will need five separate spark sources.

If all the gaps use the chamber as the return then the gaps are in parallel. A single spark generator won't work with gaps in parallel since only one of the gaps will actually spark.

Done properly with a current balancing coil, a single current source can be current split to drive several plugs. It works much the same way a 2 tube fluorescent ballast works. If the current drops in one, it drops in the other. If one tries to draw all the power, more current is forced into the other one. There are configurations to drive 2,3,4, & 6 lamps or gaps with even current in each. This requires a proper HV transformer.

It is easier to simply drive 5 separate ignition coils from a single trigger source.

jimmy101 · Fri Oct 23, 2009 1:06 pm

Technician1002 wrote:Done properly with a current balancing coil, a single current source can be current split to drive several plugs. It works much the same way a 2 tube fluorescent ballast works. If the current drops in one, it drops in the other. If one tries to draw all the power, more current is forced into the other one. There are configurations to drive 2,3,4, & 6 lamps or gaps with even current in each. This requires a proper HV transformer.

Now all you need is a current balancing transformer that puts out several channels at 10X~100X the voltage of a florescent ballast. (Startup voltage is what ~600V? Continuous voltage ~60V?)

AngryChauncey · Wed Oct 28, 2009 11:48 pm

If you are going into PVC, you can really just self tap with the spark plug itself. Take it out after you tap it and put Teflon tape on it and then put it back in.

theBOOM · Wed Oct 28, 2009 11:53 pm

AngryChauncey wrote:If you are going into PVC, you can really just self tap with the spark plug itself. Take it out after you tap it and put Teflon tape on it and then put it back in.

What do you mean self tap you mean Creating threads with the plug? sorry.. but how would you do this.. ? care to illustrate a bit

That is one way you could do it, you could also just build a sparkstrip and get a high voltace source.... that way you wont have to deal with making so many holes in your chamber which will probably weaken it some and create more weakpoints or make a future failure point.... anyway just my opinion.

AngryChauncey · Wed Oct 28, 2009 11:55 pm

You use a drill bit a hair smaller than the spark plug, drill a hole, and then use the spark plug as the actual tap. If you do it right, it's the same thing as tapping it.

Coodude26 · Thu Oct 29, 2009 12:03 am

IE, a wood screw is technically self-tapping. It screws in on its own.

BTW, Sparkstrips do not need to continuously feed in & out of the chamber. If you have a couple flat pieces of copper, they can be bent & put in the barrel like this:

___| ~ |____| ~ |____| ~ |______

~ being a spark.

AngryChauncey · Thu Oct 29, 2009 12:07 am

IE, a wood screw is technically self-tapping. It screws in on its own.

Thank you for the update professor

.
Anyways a spark strip with a stun-gun is the way to go.[/quote]

Coodude26 · Thu Oct 29, 2009 4:45 pm

I was just extending what you were saying to theboom.

kjjohn · Thu Oct 29, 2009 6:12 pm

jimmy101 wrote:
kjjohn wrote:I am thinking of wiring up 5 small spark plugs in a metal chamber for my hybrid. I am going to use the spark plug electrode as the HV wire, and the chamber itself as the return. How do I insert a spark plug through the side of the chamber? I am thinking that I will just use a tap, but I want to make sure I do it right. I have never done this before. Do I have to drill a hole that diameter into the chamber first, then use the tap?
That means you will need five separate spark sources.

If all the gaps use the chamber as the return then the gaps are in parallel. A single spark generator won't work with gaps in parallel since only one of the gaps will actually spark.

I've worked with electronics many times before, as well as high voltage, but I have never had problems wiring circuits in parralel. If I have a 50kv coil, with the chamber as the return and the spark plug terminals obviously as the HV line, the voltage will be the same for each plug. I can see how this many plugs would be a problem in series, but not in parralel. Unless the amperage becomes too low, as ignition coils are fairly low amperage anyway, but I still don't think that 5 spark plugs is enough to lower the amperage enough (per spark plug) to only allow ignition in one of them.

Technician1002 · Thu Oct 29, 2009 7:40 pm

kjjohn wrote:
I've worked with electronics many times before, as well as high voltage, but I have never had problems wiring circuits in parralel. If I have a 50kv coil, with the chamber as the return and the spark plug terminals obviously as the HV line, the voltage will be the same for each plug. I can see how this many plugs would be a problem in series, but not in parralel. Unless the amperage becomes too low, as ignition coils are fairly low amperage anyway, but I still don't think that 5 spark plugs is enough to lower the amperage enough (per spark plug) to only allow ignition in one of them.

Have you worked with the dynamics of an arc? Air resistance changes from near infinity to often less than 100 ohms when broken down. First arc will take the current and drop the voltage preventing the other gaps from reaching breakdown voltage.

Only a really high series resistance can prevent loading it or a current sharing transformer to ensure several gaps are driven with the same current by raising the voltage on the second gap when a current is drawn on the first.

Arc welders, carbon arc search lights and the like run on less than 50 volts across the arc. Open circuit voltage is considerably higher. Carbon arc lamps typically have 70 volts as the open circuit voltage. Arc current is limited by a ballast resistor.

Spark plugs

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