A Complete Guide To Spark Plug Performance
(origianlly posted on the now defunct Cooper Auto site - reposted here due to popular demand)
So What Does a Spark Plug Really Do?
Design and Technology
Why Do I Need To Use a Resistor?..
How Does Heat Range Affect a Plug?
Which Spark Plug Design Is Best For My Engine?
Will The Use of Champion Spark Plugs Affect My Manufacturer's Warranty?
Firing End Conditions
Normal Firing End
|So What Does A Spark Plug Really Do?|
The definition of the spark plug's purpose is straight forward. A spark plug seals the combustion chamber. It conducts a spark that is generated in the ignition coil into the combustion chamber and provides a gap for that spark to jump across. Finally, it conducts the heat it picks up in the combustion process to the cylinder head and into the cooling system. When a spark plug provides these three basic items, it is then capable of initiating the combustion process, There is a large amount of technology which goes into the design and manufacture of a spark plug that meets these requirements and provides long life and superior engine performance. It is important to remember that there is no design that will allow a spark plug to generate more voltage or hotter spark because the spark energy is generated in the coil. It is also important to remember that spark plugs do not produce heat. They pick up heat from the combustion chamber and move it to the cooling system. This basic definition of a spark plug will benefit you as the features and designs of Champion spark plugs are described. It will also help you to better understand the value of reading spark plug firing end conditions.
|Design and Technology|
The spark plug is made up of three major components: the shell, the insulator and electrodes. There is intense, ongoing research and development to improve all aspects of spark plug performance. Let's discuss each individual component.
The shell of a spark plug is a threaded metal hex that is used to seal the combustion chamber and provide a means to remove and install the spark plug. Shell dimensions are standardized within the industry. Both SAE and ISO have a set of standards which cover hex size, thread diameter and thread pitch. Most shells use an extruded steel to maintain exact tolerances. The extruded shell goes through a cold rolling process to form the threads of spark plugs. This prevents sharp edges which could cut new threads into aluminum cylinder heads. Modern automobiles use two types of seats to seal the combustion chamber - a gasket type which mates to a flat machined surface in the head, and a taper type which mates to an angled seat in the cylinder head, In most engines, these designs are not interchangeable. However, some late model General Motors engines have specially machined heads that can accept either.
Once the shell is formed and threaded, it is zinc-plated to extend its life and reduce the chances of seizure in aluminum cylinder heads. Our latest technology combines TinTac" and ULTRASEAL'M coatings over the plating to further reduce corrosion and seizure. This patented process is the result of our development work with 100,000-mile plugs and is used on all Champion spark plugs.
The second component of a spark plug, the insulator, has two functions. First, it insulates the secondary ignition voltage from grounding anywhere except across the gap in the combustion chamber. Its second function is to move the heat picked up in the combustion process into the cooling system. Champion insulators are made of a premium grade ceramic which consists of high zirconia content alumina oxide. This ceramic is able to contain the highest voltages used in today's ignition systems, while actually thriving in the harsh combustion chamber. The ribs at the top of the insulator are designed to prevent the spark from traveling to ground along the outside rather than the center of the spark plug. On most ignition systems, lack of these ribs can result in intermittent misfire and reduced engine performance.
The last major component of a s ark plug is the electrodes, These are designed to conduct the spark from the spark plug wire into the combustion chamber and to provide a gap. Champion Copper Plus spark plugs use a high chromium nickel alloy to provide long life and performance. Chemicals created in the combustion process are often corrosive and will quickly corrode lesser metals. In order to further extend the life of a spark plug, Champion uses a copper core in the center electrode which actually reduces the electrode tip temperature, further reducing electrical erosion and chemical corrosion. Champion pioneered this technology and today provides copper cored ground electrodes for the ultimate in long life. Further improvements in spark plug performance (life) involve the use of precious metals. Champion manufactures long-life spark plugs that use iridium, tungsten, silver, platinum and gold palladium electrodes. For automobiles, platinum and gold palladium have proven to be the most beneficial and are used in Champion Premium Gold and Double Platinum plugs.
|Why Do I Need To Use A Resistor?|
Today's spark plugs use resistors to eliminate radio frequency interference (RFI) which can affect on-board computer systems, AM and FM radio reception, TV broadcasts and even airplane communications, Each time the spark jumps across a gap, an electromagnetic field is created that can interfere with radio signals, By placing a resistor in the spark plug, we can substantially reduce RFI. Furthermore, the use of non-resistor plugs with today's complex computer systems can result in driveability problems, loss of performance and can even cause the computer to store trouble codes.
At one time, resistors were the weak link in spark plugs. The old technology was to make resistors out of carbon and epoxy. Just like a spark plug wire, if excessive heat or an electrical arc developed inside the plug (not at the electrode), the resistor could quickly be damaged and cause a misfire. Champion has patented a semi-conductor resistor, called SAC9, which suppresses RFI below SAE J551 standards and will not fail under any circumstances in an automotive engine. It is made up of strontium, aluminum oxide and copper oxide. This semi-coflductor will not be affected by either internal arcing or the wide range of temperatures found under the hood. It increases both the life of the spark plug and its ability to suppress RFI.
|How Does Heat Range Affect A Plug?|
As we've discussed, a spark plug is made up of ceramics, steels and nickel alloys. These materials do not have the ability to produce energy or heat. When we talk about the heat range of a spark plug, we're referring to its ability to move heat away from its tip or core nose into the cooling system. A cold spark plug would have a cooler tip temperature than a hot one. With today's fuels, we know that anytime the tip of the ceramic core nose goes below 850 F, carbon will build up and the spark plug will foul. We also know that if the tip temperature of the plug exceeds 1550', the metals will begin to break down. At approximately 1700, the plug will glow and can become a source of pre-ignition within the combustion chamber. Armed with this information, it becomes clear that maximum performance can be achieved with a spark plug that has a temperature of greater than 850 at idle, but no more than 1550' under wide open throttle. Rather than using the industry standard cross-referencing, Champion uses thermocouple spark plugs to read tip temperatures of a spark plug in an engine and determine the proper heat range. Champion actually tests each application listed in its catalog every year for proper selection rather than depending on other companies' testing. Our ability to do live testing on engines allows us to quickly adjust our application information to changes in fuels and other factors, which are not spark plug related. Because of our extensive thermocouple testing, Champion strongly recommends that plugs not be selected based on cross-referenced information, but be selected based on the application section of our catalog.
|Which Spark Plug Design Is Best For My Engine?|
Champion has four lines of automotive spark plugs, each one designed to meet the need of a particular segment of the automotive industry.
Champion Copper Plus is a spark plug line that leads the industry with innovative performance benefits. Copper Plus is available for all import and domestic vehicles and carries the best warranty of two years/unlimited mileage. One of the features that makes the Copper Plus stand out among other spark plugs is an extra hard and dense ceramic insulator. This allows flawless functioning with high energy ignition systems, while maintaining extremely accurate heat ranges. Champion uses an extruded copper core in our center electrode which allows for accurate control of heat range, optimizing the performance and fongevity of the spark plug. A patented semi-conductor resistor is used to remove RFI from on-board electronics and assures maximum plug life. Our zinc plated shell uses TinTaC« and a patented process known as ULTRASEALTM which eliminates the need for use of anti-seize compound when installing spark plugs. This process provides the best corrosion protection of any spark plug in the industry.
When only the best will do, Champion Premium Gold is the plug of choice. In addition to the benefits described for Copper Plus, Premium Gold utilizes a precious metal insert on the center electrode which drastically reduces electrode wear, providing the best performance over a longer period of time. Because wear on the center electrode is virtually eliminated, its diameter has been reduced by 20%. This smaller diameter allows for reduced voltage firing requirements and contributes to smoother idle and better acceleration. Premium Gold also uses its exclusive copper cored, inverted V-tip ground electrode. By extruding copper into the ground electrode, it runs up to 3000 cooler, minimizing wear and pre-ignition. Champion Premium Gold carries the best premium plug warranty in the business of three years/unlimited mileage.
Champion Truck PlugTM was designed specifically for pickup trucks and sport utility vehicles. Features include a black glazed, zirconia-enhanced ceramic insulator which offers 40% more strength than other spark plugs. This provides durability under rough driving conditions. The massive copper cored it center and ground electrodes are 20% larger than ordinary spark plugs. This design allows the plug to thrive in the rough environments of trucks and sport utility vehicles. Tests have shown substantial increase in electrode life over standard designs in truck engines. The plug carries a threeyears/unlimited mileage warranty. When you want a no-compromise spark plug for a truck or sport utility vehicle, Champion Truck Plug is the only choice.
This spark plug not only embodies all I technology available for spark plugs used manufacturers such as GM, Chrysler, Mitsubishi a Toyota, but it's actually the OEM design for these engines. Tapered cone, platinum center electrode and platinum tip ground electrodes provide the ultimate in long-life design. Our patented ts ULTRASEALTM and TinTac® coatings assure ease of spark plug removal, even after 100,000 miles. Our zirconia enhanced insulator will live under the most demanding ignition requirements in the industry. In all, this spark plug is the original equipment lly replacement for your engine. In addition, the Champion Double Platinum design carries an unheard of five-years/unlimited mileage performance guarantee.
|Will The Use of Champion Spark Plugs Affect My Manufacturer's Warranty?|
Absolutely not! Champion extensively tests each engine design using patented thermocouple technology to determine optimum spark plug design and heat range. Our testing assures that we meet, and in many cases, exceed OEM specifications. Often, the OEM design is simply a Champion spark plug which we have privately labeled for that car manufacturer. Under no circumstances will Champion spark plugs have a negative impact on the manufacturer's engine or emission warranty.
Here are a couple of tips to help assure the success of changing spark plugs. The first is to remove spark plugs from aluminum cylinder heads only when the engine is cool. Since aluminum and steel expand and contract at different rates, removing spark plugs from an aluminum cylinder head while hot can actually cause thread and cylinder head damage. Before installing the spark plugs, make sure the threads are clean and in good condition. If in doubt, run a thread chaser through the plug opening in the cylinder head. Champion recommends that you do not use an anti-seize compound, since one has already been applied to the plugs at the factory. Next, install the spark plugs finger tight and, it using a taper seat spark plug, use a ratchet to rotate 1/16 of a turn. If using a gasket seat type spark plug, after installing finger tight, turn 1/4 to 5/8 of a turn. If this procedure is followed, spark plugs will not back out nor will they seize in the cylinder head.
|Firing End Conditions|
We have provided a list of firing end conditions to help you identify situations that may occur in your vehicle. It is helpful to use a magnifying glass to view these deposits. Champion recommends the use of our service tool CT456. This is a 5 power magnifier with a light that will allow you to see small deposits on the corners of the spark plug and make an accurate diagnosis.
|Normal Firing End|
A grayish tan to while color indicates the correct heat range spark plug is in use, the fuel and ignition systems are in good shape and overall engine mechanical condition is good. Replace with Champion plugs of the same heat range. Refer to the owner's manual for recommended spark plug change interval.
Worn or rounded center and/or ground electrodes indicate excessive wear and can cause misfire during acceleration, hard starting or reduced fuel economy and damage to other secondary ignition components e.g., spark plug wires, coils and distributor cap with continuous use. When a plug has this type of appearance, it has simply exceeded its useful life. Replace with new Champion spark plugs of the same heat range and design.
In cases of light detonation, small black or gray spots will be noticed on the core nose of the spark plug. In cases of severe detonation, insulators may be cracked and/or chipped. The same high pressure waves created during detonation can break spark plugs, damage intake valves and break pistons. Make sure that the correct octane fuel is being used, assure proper operation of emission and computer systems (paying special attention to the EGR system) and assure the correct heat range of spark plug is being used.
Bent and/or broken electrodes and core nose indicate mechanical damage caused by foreign objects in the combustion chamber or improper reach spark plugs, Remove the foreign object from the engine and check the Champion catalog for proper spark plug application.
Chalky white insulator with little or no coloration, accelerated electrode wear and possibly blistered or pitted electrodes are indications that a plug has overheated. The shell may also be discolored from light gray to a dark blue, almost black. Check for the correct heat range spark plug. Verify that ignition liming and air fuel mixtures are adequate and that all emission systems are operationaf. Inoperative or malfunctioning EGR systems are often the cause of an overheated condition. Engine overheating and restricted exhaust systems can also cause this condition.
Light brown deposits encrusted on the ground and/or center electrodes indicate ash deposits. This situation is caused by oil and/or fuel additives. When the deposits are found on only one side of the spark plug core nose, it is usually considered to be a problem with the cylinder head (valve stem seals or valve guides). When they are found on both sides of the spark plug, it is often considered to be a problem sealing at the piston rings. This condition can mask the spark and, in some cases, contribute to misfire. Check for worn valve guides and valve stem seals and/or piston rings. The spark plug is the correct heat range and was a victim of the engine's condition, not the cause of it. Champion does not recommend the use of fuel additives which leave deposits on the core nose of the spark plug.
Symptoms of oil fouling include black oily coating caused by poor oil control. This situation is more severe than what is seen with the ash-fouled spark plugs and usually represents advanced engine wear. When the oil enters the combustion chamber and covers the core nose of the spark plug, the spark no longer arcs across the gap. Rather it takes the easier path to ground by tracking down the oil on the core nose. This results in a complete cylinder misfire condition. Check for worn valve guides, valve stem seals and/or piston rings, In some engines, a defective PCV valve can contribute to this condition. Replacing the spark plug may help for a short time, but the new plug will soon foul.
Signs of the spark plug being hot or blistered and/or melted center and ground electrodes are indications of initial preignition. Check that the correct heat range spark plug is being used, assure ignition timing and air fuel mixture are appropriate, assure entire ignition system is functional and check its specifications. Pay special attention to the EGR system and/or knock sensors. Routing of spark plug wires on some engines can contribute to cross induction which will lead to pre-ignition. Excessive carbon deposits in the combustion chamber may contribute as well.
Melted center and/or ground electrodes and/or a melted insulator are symptoms of sustained pre-ignition. See initial preignition, description above. Also expect to find damage to the pistons and/or exhaust valves.
Small islands of contaminants on the insulator indicate splash deposits. Replace with new Champion plugs of the correct heat range. The use of fuel additives, carburetor and choke cleaners or other aggressive solvents before installing new plugs is the most common cause of this condition.
Soft, black, sooty, dry-looking deposits indicate a rich air fuel mixture, weak ignition or wrong heat range spark plug (too cold). These carbon-based deposits are conductive, much like oil fouling, and will allow the voltage coming out of the center electrode of the spark plug to track down the core nose rather than jumping the gap. This will result in an engine misfire and further aggravate the carbon fouled condition. Check for correct plug heat range. On fuel injected engines, check for sticking injectors, malfunctioning cold start valves and/or circuits. Also check for correct fuel pressure specifications. On computer controlled vehicles, the "limp home" computer mode will always result in a rich condition. Therefore, it is imperative that you check the operation and condition of the on-board computer system. On carbureted vehicles, check choke and choke pulloff, high float level, and needle and seat condition. On all engines, severe vacuum leaks can decrease manifold vacuum, resulting in a rich condition. Weak and/or damaged secondary ignition systems will fail to spark across the gap lowering combustion chamber temperatures and promoting carbon deposits. This condition could also result from continuous low speed driving or poor cylinder compression.
Red to purple deposits on one side of the core nose are an indication of a fuel additive. While many of these deposits are non-conductive and do not contribute to lack of performance, some fuel additives contain octane boosters that leave conductive deposits on the core nose. Care should be taken to select fuel additives which are compatible with ignition systems and do not contain conductive materials such as octane boosters.
Copyrightę 1998 Cooper Automotive
This page was edited on: May 3, 2004