Spark Plug mod

Anyone try this one? The plugs are also sold commercially but I did not link that site, smelled too much like snake oil. The mod could be a DYI though.


Basically its drilling a .039 hole in the ground electrode of a spark plug.

Hogwash-- Voltage takes the easiest path and thats the very edge of the electrodes. There have been a thousand different plug designs but a plug serves one purpose-- it provides an airgap. LEE

It would be a waste of time at best.  Don't bother.

Basic electricity: voltage pushes, amperage works. The hole in the electrode is a plausible idea. That doesn’t mean it’s a fact. I can think of a theoretical model of a plasma jet through the hole and, maybe, having beneficial results. Drilling a hole costs nothing for a do-it-yourselfer. The world will end if you actually try it?

Two things stand out. The claims that obscuration produced by the ground tang inhibits flame propagation and the production of a “jet” of combustion through the newly formed aperture in the tang. If the first issue is to be believed, then why not simply switch to marine plugs? You know, the ones with no ground tang? I would have preferred to see some visual evidence of this “jetting” phenomenon. It doesn’t seem likely as the combustion will occur all around the spark and has no “incentive” to jet through the hole at a rate faster than the surrounding flame front.

They talk a bit about voltage versus amperage and it’s true that the spark intensity is a primary factor in igniting less than optimal mixtures. Increased voltage overcomes marginal conditions like fouled or worn electrodes, corroded connections, etc. Back in the sixties, people were marketing buttons you install in your distributor cap to increase coil saturation voltage- a button resistor was all that was.

All things being equal, higher voltage will produce a hotter spark. But that’s not the be-all-end-all of what makes an optimally running ignition system. Simply reducing spark plug resistance may produce unwanted side effects like RFI. The OEM system is designed with a wide range of considerations, not just spark intensity. The peak spark energy may be damped to produce the same amount of energy but spread over a longer period of time. Not so hot initially but able to survive poorly mixed combustion gases and not produce interference with electronics as two examples.

I don’t buy a bit of this garbage. The part that caught my eye was the bit about “heat” being the determining factor in combustion rather than voltage. Note they refer to setting the plug gaps at .030 to .035. If you narrow the plug gap on any spark plug it is going to take less voltage for that spark to jump the gap and heat or amperage has nothing to do with this. Narrowing the plug gap from say a factory recommended .050 to .030 can help prevent a plug misfire in the short term. In the long term the plug life may shorten since it will have a tendency to build up deposits and foul more easily.

They’re also making reference to the ground electrode shielding the flame front when it starts. True, but pretty much irrelevant.

If you want to make a couple of spark plug modifications that have been dyno tested and proven then you should do this.

  1. Round off the end of the square tip on the ground electrode into a semi-circle. (Some plugs come from the factory now like this.)
  2. Index your plugs. This means that you need to have the open side of the spark plug gap facing toward the center of the cylinder. This is done by placing a felt tip pen mark on the spark plug body to indicate the open side of the gap and noting that the mark is facing generally towards the center of the cylinder.
    It does sometime require buying 2 sets of plugs and interchanging them due to the cut of the threads, but those 2 modifications alone have been dyno proven to add anywhere from 2 to 5 HP on a street engine. Almost all of the race car guys do this.

One thing that would bother me…is it might change resistance. If it does it could produce engine noise on the radio.

I noticed the drawing was done before irridium plugs…with their nice pointy little center electrodes. And their nice hard irridium.

Love to play with ideas like this in a lab setting. Just for fun. I couldn’t actually justify the time to do this to a set of plugs. I have serious doubts.

I’d have said “What a load of hogwash,” but several others have pre-empted me. I will second the concerns about decreasing the wires’ resistance causing increased RFI. Maybe nobody listens to car radios any more, at least not to AM.

But note their basic claim: “The mileage gain is not huge but it is steady, and you get better performance.” And they say that they have drilled “perhaps 1000 plugs”. Now, even if all those plugs were in 4-cyl engines that would be only 250 engines. How long would you have to use those engines and monitor their fuel consumption and accurately compare it to an accurate baseline in order to demonstrate a “not huge” difference. And they don’t even present any data! And what other “performance” are they improving, and where is that data?

I think I’ll say it anyway: What a load of hogwash.

“This is done by placing a felt tip pen mark on the spark plug body to indicate the open side of the gap and noting that the mark is facing generally towards the center of the cylinder.”

Don’t use a black felt tip pen on the ceramic part of the plug. Some black pens use an ink that is conductive, Not all but some. Just to be safe, use a color like red or blue. You can also make the mark down on the base where it wouldn’t matter if it is conductive.

You don’t usually need a full extra set of plugs, one additional might be all you need, but I’ve never even needed that. There is a lot of latitude since all you really need is to keep the ground electrode from shadowing the center of the combustion chamber. In 4 valve per cylinder designs, it doesn’t matter as the spark plug is in the center of the combustion chamber.

In addition to rounding off the ground electrode, another trick is to shorten it so that it only covers about half the center electrode.

I posted this to see if anyone had tried this. The reason I was a little more open to this one is that this guy isn’t trying to sell anything, or if he is, I missed it. There is another web site trying to sell these modified plugs for $5.95, but they made more outlandish claims and used some mumbo jumbo that was pure, unadulterated B$. As far as spark intensity, neither one of these guys has a clue. There is more to it that voltage and current.

EMI created inside the combustion chamber, and a lot of EMI is produced inside the combustion chamber, doesn’t affect you radio. All the metal around the combustion chamber does a pretty good job of shielding it. I don’t think the hole changes the resistance of the plug at all.

You’re right, but the collapsing field in the coil is not shielded very well.

When I mentioned the resistance change, it wasn’t due to the hole. They talk about getting plugs with no more than 5000 ohms to increase spark intensity. There’s a very good reason the manfrs spec and use the parts they do…

Looks like I’ve wasted five perfectly good minutes to read this, thanks for posting.