What Spark Plugs to use

[dkjones96]

I have a few people on here with the plugs in hand. I am eager to see what they are seeing out of the plugs.

There are a few cars out there that see little to no increase out of the plugs. The jeep 4.0 is one of those very engines. It will see a bit of an increase up top and owners say they feel a big difference down low at part throttle but we haven't run dyno tests at part throttle yet. Going from a long projected tip plug to a normal plug I'm not surprised to see a smaller increase than most other side plug engines but there are still gains to be had. When that happens to be the case, you return them, but those engines are usually few and far between. At least one person on here with a VX has plugs.

On that C6 in that link, one thing the story doesn't say is that while we didn't register any performance increase on that particular vette, here in house, not only do we have others that have seen an increase and been tested by an independent source here but after the stock plugs were changed out with our plugs the air fuel ratio trims did need adjusted because the O2 sensor was reading a leaner exhaust stream.

I wouldn't be working for a company if I had even the slightest hint that it was selling a product didn't actually work, anyone should be able to understand that.

[GasSavers_RoadWarrior]

There appears to be some vehicles that hate bosch platinums, general consensus on Ford Escort and FWD Mopar forums is that they are awful in those cars. Notably the Escort uses an EDIS system which is much favoured as an upgrade for older cars and for use with megasquirt, and the mopars have a coil that has quite high voltage output. So I don't know if you'd consider either ignition system as particularly weak or anything. There's a potential I guess that too high a resistance in the plug causes flashover further back somewhere if these systems are kinda of at the limit for what normal plugwire insulations handle.

Myself I've had the NGK G-power in my '88 voyager and wasn't impressed, in fact when I put standard Champions back in after a year or so of "suffering" them I seemed to pick up 1 or 2 mpg and power seemed up a hair. Currently messing around with sidegapped AC Delcos I go cheap, think my coil has been getting weak though, and forgetting to set the gap narrower was a mistake. However, it passed an e-test and seems good at the top end, but idle and low end could be better. Soon going to swap a newer coil in and probably inspect and re-gap them.

[gto78]

I'm thinking that better spark plugs only make a difference on vehicles that are inefficient in the original design. What I mean is, some engines are not very good at burning fuel, possibly the cam design, or ignition timing etc. On those engines I believe you'll see the biggest increase in fuel economy by installing pulstar plugs. But if the engine is already running at peak condition then there's not much room for improvement, except for better fuel.

Pulstars have an internal capacitor right? That causes the spark to last longer than normal, which is the same thing CDI ignition systems do (capacitive discharge ignition), which is stock on a lot of vehicles nowadays. If your vehicle already uses a cdi ignition, then installing a pulstar plug probably won't make a big difference.

[dkjones96]

Originally Posted by gto78

...Pulstars have an internal capacitor right? That causes the spark to last longer than normal, which is the same thing CDI ignition systems do (capacitive discharge ignition), which is stock on a lot of vehicles nowadays....

Pulstars do have an internal capacitor, however, that's the only thing correct in that statement. It does not cause the spark to last longer and neither does CDI.

CDI uses a capacitor in the primary loop to help create a short and accurate spark. CDI gets it's added benefit from that and by using high voltage in the primary and a transformer to the secondary so you have a very reliable way of controlling timing as opposed to relying on a magnetic field to collapse.

Lets look at a scope reading of the Pulstar plug going through a spark sequence.
Note: A normal spark plug has the same exact scope reading.


1)We start at zero volts, in an inductive ignition system this is when the primary is energized. When the ignition system is supposed to spark the inductive system disconnects the primary and causes a sharp collapse in the magnetic field in the coil which 'induces' a high voltage charge on the secondary. In a CDI ignition system this is when the control circuit gets the command to fire.

2)From here they are very similar except the rise on CDI is faster. The rise in voltage is called the ionization phase. This phase lasts about 4 microseconds and is where the Pulstar plug is charging and a normal plug is just sitting there.

3)The peak is called the break over. This is the voltage at which the spark is formed and depends mostly on pressure. Fuel saturation and temperature can make a difference but not near as much as pressure. When break over voltage is achieved the resistance across the gap drops to essentially nothing as the streamer is formed.

4)The sharp fall is the streamer phase and lasts about 2 microseconds. Since there is almost no resistance across the gap the amount of available energy in the system drops very quickly and is also where the Pulstar plug discharges the majority of it's power. As opposed to around 5 milliamps of current across the gap the Pulstar plug discharges multiple amps(yes, amps) across the gap. That was tested and proven true at Sandia National Laboratories.

5)Where the fall starts to level out again is called the resident phase. The Pulstar plug and a regular plug act pretty much the same here. It's a lower voltage discharge that lasts around 10 microseconds and is basically the ignition system taking further advantage of the lack of resistance across the gap and discharging what it's got left. In CDI this is a shorter phase as well because, remember, it's using a transformer.

Capacitive Discharge Ignition systems are named appropriately. They use a capacitor in the ignition system, that's a no brainer. But you can't say that a car with a capacitive discharge system will not see a benefit from the Pulstar plugs and let me explain why.

On a CDI system you have a capacitor in the primary loop. When the plug goes to discharge, even though the plug has almost no resistance in the gap you still have the resistance in the primary winding, secondary winding, plug wires and resistor in the plug itself for EMI filtering between it and that low resistance gap. With our plugs, the capacitor is after all if these resistances so when the gap reaches break over the capacitor has a resistance free path to discharge itself.

[gto78]

Great info, that much detail is almost impossible to find unless you talk to the right person. My next question is regarding the amount of amps going through a pulstar plug, or from the plug etc. I know that the ignition coil in my car is only going to use a certain number of amps from the car battery, and the output of the coils are only able to put out a certain number of amps/volts- watts of energy.

So if my spark plug wire is supplying the same amount of energy to a pulstar plug as any other plug, then where is all the amperage coming from?

Am I giving up voltage and replacing it with amperage? Where does ohms law fall in place here?

[dkjones96]

To answer your question I'm going to quote the inventor of the plug.

The area under the curve is energy (integrate to get the value) and in a spark plug this energy is wasted as heat. In a pulse plug this energy is stored in the internal capacitor.

The energy stored in the capacitor is discharged in a very hard, energy dense pulse of 1-2ns once the spark gap has been broken down. So the product compressed the energy collected from a 3.8microsecond pulse into 1ns pulse peaking the current of the discharge.

Measured current (by Sandia National Labs)during this 1ns discharge at 25kV is 1108a. An iridium spark plug discharge current at 25kV (also measured by Sandia Nation labs) is 0.5a.

In both cases once the gap is broken down with 25kV and a streamer forms a spark with the resident voltage at approximately 5V.

Formula for Peak Power: WATTS=I2V (I=current, V=voltage)
For a spark plug
PEAK POWER (WATTS) = I2 V
WATTS = 0.5a2 x 5 = 1.25 WATTS

For a pulse plug
WATTS = 1108a2 X 5 = 6.1 MEGAWATTS

This is the extreme case where breakdown occurs at 25kV. Operating gap breakdown typically occurs in the 10kV-15kV with idle breakdown around 5kV. This explains to some degree why ignition during idle is somewhat difficult and why multiple spark was coined to address idle only.

You can see the article submitted to SAE here.

[gto78]

That's a complicated answer. I still don't understand. If my spark plug wire is providing a total output of say 10 watts of power, than 10 watts is the total output period...right? No matter if the old plug wasted half of it with heat, stored it, shorted it out or anything else, the total amount of energy (watts) present is still the same unless I make a change to the ignition coil.

That formula above says the pulstar is providing 1,108 amps... that's 6X as much current as my starter uses. If there was 1 thousand amps going through the tiny electrodes on the spark plugs several times a second wouldn't they melt?

I'm going to guess that the pulstar plug does not initiate it's spark at the same time as a regular plug. With the above explanation from "pulstar" it seems to me that the plug starts charging it self with energy when the car's secondary coil discharges at the instant the piston reaches it's correct number of degrees before top dead center. The old plug normally would have sparked, but 3.7 ms later the pulsestar plug finally sparks but for only a 1ns period. During that 1ns spark it will have a lower voltage but higher current to maintain the same total wattage output... I'm probably wrong but that's how I read it.

[gto78]

OK, I think I got it all figured out. I take back all the bad things everyone else said...J/K. Basically the traditional style spark plugs are wasting an enormous amount of energy by transferring it into the form of heat during the voltage ramp up that occurs at the beginning of the ignition cycle. This build up takes several milliseconds until the voltage reaches a point where it can overcome the near infinite resistance of air and then finally sparks. On a pulsestar this same "build up" is simply charging a capacitor and storing all the power instead of wasting it as heat. Then it reaches a point where it is able to overcome the resistance of open air and throw a spark- but the difference is this spark has a capacitor supplying the power directly at the point of discharge. There's nothing wasted, and the spark only lasts 1ns.

My new question is this: how does a more efficient spark thats only 1ns long able to save me money, and how does it increase fuel economy? I see the insanely huge increase in spark efficiency, but I don't know how that will burn more of the fuel more efficiently. I can see it making a difference in a car that is running too rich or a car that has poor combustion characteristics, but not all cars are running overly rich.

[dkjones96]

That is exactly how it works. It's a huge amount of power but it stores the power over a longer period of time and releases it over a very short one. Think camera flash, the AA batts charge the capacitor over a long period of time and in an instant all that power is thrown through the flash bulb to create a light the batteries could never do alone.

The spark lasts just as long as with a normal plug. Remember, you can't really see a difference in the scope readings of a Pulstar plug and a normal spark plug. Timing and duration are the same. Intensity at the very first part of the actual spark is where it's different, but you still have an ignition system with voltage sitting in it behind the plug that needs to discharge after that fact.

How does this improve fuel economy in a good running engine? There are a couple of reasons it works in good, healthy engines.

First off, you can see in the picture I posted that it's a visually brighter spark. There is a lot of light we can't see one of them being ultraviolet light but more importantly, infrared light. This heat radiation that's created by the spark not only ignites what's right at the spark faster but is able to ignite fuel and air at a short distance from the plug. If you go about halfway down THIS page and look at the plug comparison(red start button) you can see what I mean. At the point the spark happens you get a quicker initial burn rate near the plug and that's the extra heat at work.

Now, when the spark is formed it's going to superheat the air and cause a compression wave exactly like lightning does to create thunder. This is the second part. That bigger spark also creates a bigger compression wave to help further agitate the fuel air mixture and help you get a better burn after the initial spark has taken place and the flame front is making its way to the far sides of the combustion chamber.

These are things that even a healthy ignition system can't do.

[GasSavers_RoadWarrior]

Hmmm compression waves are usually bad. That's what shoves mixture against the walls and makes it detonate rather than burn.