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FyreDaug
08-16-2006, 10:49 AM
At TDC how close is the piston the electrode on the spark plug? Assuming its a stock gap of 0.045 would you say the piston is as close as another 0.045? Or more?

Reason I ask is because Ive been planning out a quad ignition coil system for some time and I think I may have figured out the charging issue the coil may have, but I havent actually put it to work yet.

We all know a spark will take the shortest distance between 2 point, so if we were to remove the lower electrode of the spark plug (so its just the exposed tip) it wouldnt work at all right? Right.

One thing I dont know is if our spark plugs we use have built in resistors that we can either remove, or use plugs without them.

Why? Well spark is the most important thing of combustion, so the bigger the spark the better. So why be limited to 0.045" of a spark, when you can have significantly larger? I dont know if this idea will work, and it may not be the best way of doing it but heres the idea, the spark ground after being fired goes to the lower electrode, and up to the engine and back to the battery or whatever. What if we used the piston as the ground? This totally depends on the clearance we have, but if and open valve can be hit, maybe the distance isnt too big (maybe custom longer spark plugs even) and the spark could jump from the electrode to the top of the piston.

Each spark plug will have an ignition coil on it that has constant power to it, but since the plug doesnt have an electrode the only way it would ground is if the piston got close. And this doesnt give you ANY tuning for ignition timing, problems involved is if its only firing right at TDC (closest point) isnt quite the best time to be firing the spark (where as, slightly advanced before TDC is the way to go).***************

So what about this, each plug will have a relay in it aswell. Use the distributer to put a 12V signal to the main point (where the coil normally connects to) and when it spins, it gives 12V out to each cap terminal. With that 12V you can send that to a relay. The relay will control the actual spark wire going to the plug. The problem I see with this, is that if the spark is able to jump the distance to the piston itll probably be able to jump around inside the relay and pretty much bypass it and be constant anyways.

Then theres the idea I had before, about skipping the whole relay thing, but using the 12V dizzy. As it turns and gives the 12V out at each point that 12V will go supply the coil with the 12V power it needs to create the spark. Problem I see with this one is that the coil will be turning off and on 4 times each second for each cylinder at 1000rpm, and I dont think itll be able to "charge" in time to give the 30000V it uses to produce a spark.



************- Is there any way to have the coil have the constant 12V they need to operate, and a constant connection to the spark plug aswell, but be able to trigger the coil when to fire? (aftermarket coil maybe?)
I dont know too much about our stock coils, but I know there are 4 wires going into it, and 1 coming out (ignitor). 1 of them going in I imagine is positive (ground being the bolt connected to the frame) and there are 2 coming from the distributor that connect to the coil (not sure what that does) and an extra wire which I dont know what it does. Can someone clear this up for me? Because if this is possible to trigger it while its on, this idea is much more plausible (esp with higher powered aftermarket coils)
As for tuning issues, may not be a problem. The ignition will essentially be retarding itself as the rpms get higher because the piston is moving faster, and advance slightly during lower rpms. No need for vacuum advance or anything either. This seems like a hit or miss issue though (no pun intended)


So imagine the spark behaving like this, instead of acting normally or grounding to itself in anyway that it does use the piston, what if the plug was just long enough, that contact is made at about 12* before TDC, thats where it is close enough to arc. So during the engine rotation, the spark will be that long for the 12* until it gets to TDC, then for another 12* on its way down (if it can reach 12* on its way up, it can reach 12* on its way down too) So you will DEFINATELY be getting a full explosion going on.

I just need to think of a way to make this work now.

2ndGenGuy
08-16-2006, 12:32 PM
I'm pretty sure that lots of high end sports cars use individual coil packs on each spark plug. That way they're electroncially controlled, and the timing can be adjusted more precicely by the computer. My friend's base model 97 Corvette has this. I think thats something thats faily easily attainable to try to set up.

As far as your idea with grounding out on the piston, I don't think you'll be able to do so. You'd have to have a HUGE arc. It would probably just arc onto the head first, since thats always going to be closer. I don't think that it will give you any performance benefits anyways, unless you're running fuel thats harder to ignite or something.

Besides to make the arc that long, you're goign to have to increase the power of the coil quite a bit, and that will just cause your wires to burn out.

FyreDaug
08-16-2006, 01:05 PM
But there is no electronic controls on this car, its carbed (well its the kart project) and actually, I dont think it would arc to the head, it would rather carc to the side of the spark plug (well close to the head anyways) I guess that wont work. Though it would be cool to have a long/big spark

A20A1
08-16-2006, 01:18 PM
The lower electrode? you mean the outer electrode.

It sounds like you want to build a corona discharge ignition system.

Those are supposedly much more efficient and the flame is larger/faster.
But they require a longer rise time... but this can be compensated with by advancing the distributor.

You might have to modify your plugs center electrode too...

FyreDaug
08-16-2006, 01:58 PM
Link to the corona discharge system: http://carambola.usc.edu/research/coronaignition/

Well it seems a little more advanced than what I am trying to come up with, though everything usually is more advanced if you want it to work.. Ill look into it

A20A1
08-16-2006, 03:27 PM
Take a look at the power point presentation.
http://carambola.usc.edu/research/coronaignition/coronaengine.html