A burning question:

HuntingTarg

Tuner
Points
52
Location
Cali USA
Car
'02 Kia Spectra LS
I have a wonderment:
[Danger Will Robinson! Highly electrical content ahead.]
Whether one thinks they work better or not, PulStar is known for making spark plug capacitors, which concentrate and suddenly release the energy of DC current going to the plug. Most modern engines now use ignition coils instead of a distributor, which has a solenoid to time the firing of an individual spark plug instead of a distributor that times the firing of all spark plugs.
Putting an induction coil and a capacitor in the same circuit run, series or parallel, when subjected to AC produces something called a RESONANCE FILTER or a FILTER circuit. It allows AC of a particular frequency to be admitted and all other, non-resonant frequencies to be dampened or 'filtered' out.
MY QUESTION IS:
Even though it is variable square wave and not true AC, could combining capacitors and induction coils have the same or a similar effect in an engine?, improving delivered spark energy at a certain RPM and reducing delivered energy outside of it?
 
A shorter more intense spark is created, capacitors are notoriously unreliable as well, and won't last as long as a conventional coil IMO. Not convinced this is beneficial really, a longer spark duration will surely be better and help start the burn/bang cycle.
 
Thank you kindly for your response, honorable sir; however your input does not address my curiosity.

First off, the capacitor is added, not substituted for the ignition coil. Without coils, there would be no electronic timing control, because the coil is what enables a very low voltage to be transformed into a very high voltage. Pulstar's redesign integrates a capacitor into the spark plug instead of selling add-on boots. I'm sure they found a good temperature- & vibration-resistant dielectric or they'd've run afoul of consumer lawsuits over engine failure the same way the maker of Slick-50 did.

I have to disagree that a longer spark is better for one reason; energy density. What happens with a capacitor in DC is that it stores up energy until it reaches its charge capacity (measured in joules if I remember correctly), and then discharges. This discharge is based off of the capacitor's electrical specs: in this application it has reduced current but increased voltage, a voltage even higher than what is required to arc across the plug gap. It durates for less time but has an increased ability to break chemical bonds, which is the whole point of creating an electrical arc in a combustible mixture. If the model is accurate, this should ignite more molecules in less time, producing a hotter flame front which will cause the rest of the air/fuel mixture to burn more quickly and completely.
Whether this results in actual performance improvement and whether it is worth quadrupuling the cost of otherwise inexpensive parts depends on the car and the driver. I saw a video, rather smartly done, that superimposed a stopwatch on the speedometer of a particular car (Mazda rx-6, if I remember rightly), and did 0-60 mph runs with the only change being from NGK Iridium plugs to PulStar plugs. 0.5 second improvement. For daily drivers, that may not mean much, but half a second can mean big things to a racer.
This doesn't mean capacitors will make ANY engine better. Finely engineered products from names like BMW, M-B, Porsche, Aston-Martin, etc. may see negligible, if any, improvement or require re-tuning.
My counterpoint is this: the theory is sound, but it's no magic bullet solution.
 
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Saab used capacitor discharge ignition in the 1988 900 model. Modern systems are usually coil per plug, with the coils mounted directly atop each plug. Earlier mechanical systems using a distributor used a single coil to feed all the plugs via a HT ignition harness.
 
It would also be interesting to see them go back to 2 spark plugs per cylinder - and with magneto ignition to boot. The Lycoming I0-360 engine runs that set up. You do a mag drop test around 2100 to 2200 rpm where you should see a drop of up to 175 rpm when you test the system by switching one mag off then the other.
 
2 plugs per cylinder is very difficult with 4 valves per cylinder. The latter arrangement allows the plug to be located centrally in the combustion chamber.
 
IIRC using 2 spark plugs was said to indicate poor combustion chamber design/flame front spread.
 
Toyota also had 4 cyl 20 Valves " in some 85 ?? Carollas as well and I seem to remember that the first/early 4 cyl Audi 1.8 turbos were also had 5 valves per cylinder.
 
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That old 1.8 turbo Passat I had was a 20 valve engine, quite an impressive array inside the hemi-head (I didn't have to take the head off mines, I got a spare cylinder head with it). Thing I thought was strange about that engine was it had a timing belt drive for one camshaft (inlet i think) then a chain drive from a sprocket at the back of that camshaft over to the other one. You would have thought there'd be some lag in a system like that but it seemed to work OK.

Back to the twin spark plugs, Lycoming's main concern was a back up in case of one plug fouling up or magneto failure so two off 18mm plugs per cylinder. I think you could get two spark plugs in a modern 4 valve head but definitely not 18mm ones. Think of the 4 valve diesels with a fuel injector and a glow plug in each.

6 or 8 mm spark plugs anyone?
 
Toyota also had 4 cyl 20 Valves " in some 85 ?? Carollas as well and I seem to remember that the first/early 4 cyl Audi 1.8 turbos were also had 5 valves per cylinder.

That's the VWs I we referring to. There was also a narrow angle V5 with 4 valves per pot in the Golf, Passat and Seat Toledo. Audi never used this motor for some reason. Possibly because many Audi models then had the engines mounted longitudinally despite being fwd.
 
This is all quite intriguing; from my experience dual spark plugs are quite redundant; I had a plug failure (on a gifted vehicle, NOT my negligence) not too long ago, and I was able to limp home on 3 cylinders and fix it myself. It has run fine for 5,000 miles since.
Yet I should point out that nothing said actually bites on my original question. Maybe it's too much electronics and not enough gears...
 
This is all quite intriguing; from my experience dual spark plugs are quite redundant; I had a plug failure (on a gifted vehicle, NOT my negligence) not too long ago, and I was able to limp home on 3 cylinders and fix it myself. It has run fine for 5,000 miles since.
Yet I should point out that nothing said actually bites on my original question. Maybe it's too much electronics and not enough gears...

Electronics are the saviour of such things. Digital domain engine management that protects the engine itself and emissions management systems from permanent damage. Limp home is better than stranded and fix it myself is better than $1000 for spoilt cats etc.

I had a plug top coil fail in my BMW on cylinder #5. ECU shutdown fuelling to that cylinder. Limp mode. The fix cost £33 for the plug top coil at a local specialist,
 

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