 Spark Plug Tech for Internal Combustion Engines - Part 3
This section of the Tech Zone will hopefully educate you in the how the Spark Plug works, and also introduce you to the techniques of proper plug reading.
SPARK PLUG TYPES & DESIGNS
There are hundreds of different spark plug types, designed for different engines, as well as specific applications.
The two main styles (simplified) we are all used to seeing are the standard tip and extended tip. It is this author's opinion that any time you can use the extended tip version, to do so. The longer tip gets the spark kernel started further into the center of the cylinder bore/combustion chamber for a more complete combustion process. This is also achieved with the use of better aftermarket cylinder heads (racing and performance applications) that are available for a variety of engine applications. In many cases, the newer head designs position the spark plug location closer to the most optimum location.
New engines leaving the manufacturer facilities have been exposed to more engineering knowledge and attention to spark plug location, chamber design, port/runner design, and piston design. Look at some of these engines closely and you will see important changes from previous designs. Good examples include: GM LS1 & LS2, GM Ecotec, and the Ford Modular. BMW. Mercedes, and other imports have always paid attention.
As a safety note though, if your engine was not designed for an extended tip plug, you won't need one or want one. What can be good for one application could be destructive to another. Don't go searching for some gimmick or exotic spark plug if your engine does not require it.
If you have paid any attention to advertising you have seen that there are specially designed spark plugs that are supposed to increase the spark kernel size. The larger the spark kernel that is created by the event of the spark jumping electrode gap, the more complete burn, the greater the power, efficiency and length of time the engine runs well before a service. The specially designed spark plugs will typically have multiple angles that allow the spark to find the easiest path to the ground strap. They may also have a larger area in or around the ground strap to allow the spark kernel to grow without as much restriction or quench, to prevent limits on size of expansive growth. The idea is good, but how the plug manufacturers go about getting the results is sometimes engineering, and other times gimmicks, smoke & mirrors, or just plain lies.
Of these plugs, there are those that work, those that are hype, and those that seem to have a good idea but they are manufactured by a company whose sole purpose is profit, not quality. Use common sense and don't believe all the hype that a marketing company is paid to bombard you with so as to confuse or stimulate you to make a purchase in their favor. The worst is getting celebrities to claim use of a product, and typically they have never personally used it. I know of one advertisement/article that claims a well-known Racer/Race Team used a particular plug on a record setting run. They had pictures and examinations of the plugs that were supposedly in that engine, and how these plugs helped with the record result. I know for a fact that the claimed brand plugs were never in that engine, and would never be in any of their (or any of their competitors') competition engines. Be Aware!
Something to also be aware of is plug material. Of the plugs I've tested on performance/racing applications, the fine-wire gold center electrode spark plugs made the best power, but at the price of also having the shortest life of any of the plugs tested. The platinum material plugs are really only good for longevity, and many manufacturers of aftermarket ignition amplifiers tell you not to use platinum if using one of their units. Platinum came about for a couple reasons. The first being the extremely small and hard tip allowed for the plug to keep clean easier (burn-off) and the second being its ability to keep its shape for tens of thousands of average miles. This played right into the auto manufacturer's hands to claim 100,000 miles before a tune-up is required. Those of us that have inspected many of these high mileage vehicles can only shake our heads, seeing the lost performance and efficiency that eroded over time. Wake Up ... It is not just the spark plugs that keep the engine running! The other problem is that platinum is not as good a conductor as other materials.
The Iridium material that showed up recently has many good traits, and benefits over platinum, including being a better conductor and being able to operate in high cylinder pressure applications. Ignition manufacturers also do not seem to be complaining about this material causing voltage leaks. The down side is the cost, and is switching to this type of plug really going to be that much better than a standard replacement spark plug? Only you will be able to decide if this is a worthwhile experiment.
How a spark plug material reacts with other materials in the engine is also important. A spark plug's outer shell must offer a perfect ground to the cylinder head it is screwed into, and how the cylinder head grounds to the engine block and rest of the vehicle. If there is a conflict in how the spark plug gets an effective ground there will be problems. A good example is on Chrysler 3.0L V6 engines. If you were to run anything other than a Champion brand spark plug in these engines there will be performance and drivability issues. It could be as simple as idle surges at a stop light, check engine light occurrences, or worse, a complete engine shutdown while driving under load (say, climbing a grade). There are other engines have these same problems, and in many cases the tech working on your vehicle may not realize the true cause being as simple as the wrong brand plug being installed. The more we see exotic materials in modern engines, the more often these annoying issues will arise.
People ask me or our tech staff all the time on plug brand recommendations, and I have to admit that most of the time we can only offer a vague answer. Not because we are trying to confuse the consumer, but because there is not strict rules written in stone somewhere. If your vehicle is stock and using the manufacturer specified plug and working fine, the only reason to change would be for experimental purposes to see if there is something better. If you have a performance application you have to start with a base plug recommendation, either by what the cylinder head manufacturer or engine builder recommends, and then go from there by reading the plugs and testing. Take to heart this statement, that "If it works, don't try to fix it ... but you could experiment to see if something works better".
I personally like the Accel plugs (made by Nippondenso), NGK V-Power, AC Rapid Fire, and the Champion Fine-Wire Gold plugs for most domestic engine applications. (for reference, we do sell the Accel plugs). Different vehicles may get different brand plugs. You may not be able to just stick with one brand and say it is always the best. On import engines the Bosch or NGK plugs usually work best. I'm not a fan of the Autolite or Split-Fire (made by Autolite with poor materials and simply a "V" welded in place of a standard ground strap) plugs. We have seen more out-of-the-box failures with Autolites than all other plugs combined. Autolites are the least expensive plugs anywhere, and they toss a lot of freebies at the race teams (read as "Marketing and Advertising"), but these teams toss the plugs after a single pass or race. Don't just look at the sticker on the side of the car, look at what hits the ground in the pits between rounds, or what is being used in the dyno cell. I do have to laugh at some of these alien-looking plugs like the +4 and others. Note that I'm not trying to bash Autolite plugs. Hell, I know some mechanics/builders that swear by them. I can only tell you what my experience has presented to me.
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