Gasoline engines are - in contrast to diesel engines - dependent on 'sparks from outside'. Those sparks must come from the spark plugs. Otherwise the gasoline-air mixture will not ignite.
Spark plugs deliver top performance in that context. If the engine runs high in revs, they can also do their job up to 60 times per second in classics. They have to do that work at high and low temperatures. Their electrical insulation capacity must be enormous and they must also seal off the combustion rooms with working pressures up to 100 Bar.
In addition, there are also many different types of spark plugs. Well more than a thousand! What remains invisible to us are things such as the wall thicknesses of the insulators, the metallic composition of central electrodes and a lot of other things that together determine the application possibilities of a certain type of spark plug. The 'heat value', or 'heat degree' is of vital importance in that context.
The heat value
We have all heard the cry 'heat value'. But what exactly does that mean? That heat value is clearly legible on the spark plug. That is to prevent that a high-revving twelve-cylinder with 150+ hp thoughtlessly gets the same spark plugs as a Ford V8 side valve. The instruction booklet or workshop manual states which spark plugs should be in your engine. Pay attention to that!
This degree of heat indicates how quickly the spark plug in question reaches its optimum working conditions. The working temperature of spark plugs is between the 600-700 degrees Celsius. Spark plugs with a too high heat value quickly become hotter than 850 degrees Celcius. This causes the electrodes to wear quickly, but it is even worse that the heat from the electrodes causes uncontrolled ignition of the mixture.
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Too cold spark plugs, the electrodes do not reach their operating temperature
At the maximum 400 degrees Celsius that occurs at that time, the electrodes quickly become contaminated with unburnt residues and the dirty spark plugs cause a poor engine run or the engine stopping.
After turning off the spark plugs, these can be 'read'. The external appearance of the electrodes tells a lot about what is going on inside the cylinders.
The good spark plugs in the right place must be able to do their job for approximately 50.000 kilometers
But it is advisable to replace them significantly earlier. You don't have to leave it for the costs. In addition, old spark plugs increase consumption and can be the reason for the death of your catalytic converter. And catalytic converters are really expensive things! Pay special attention to transversely placed V6 blocks. The 'rear' spark plugs are often so short on the bulkhead that they are very difficult to replace. They are therefore often not replaced.
It is incredible how complex these inexpensive parts are
Spark plugs consist mainly of metal and ceramic material. The insulator is compressed from aluminum oxide beads. The press form is then ground into a model. In this compressed form, the insulators are very susceptible to breakage. That is why the handling of these semi-finished products is done by robots. The stacked insulators then enter the sintering furnace to stay there for 30 hours. At a temperature of more than 1.600 degrees, the insulators shrink about twenty percent and get their final shape and hardness. After cooling, they are tested for their functioning by means of a voltage test, whereby the test voltage is 20-30 kiloVolt. After having passed this test, the insulators are provided with their texts and they receive a glass protective layer as regards their visible part.
The electrode in the spark plug consists of two parts: the ignition pin on which the spark plug cap is mounted and the center electrode. Just like the mass electrodes, these central electrodes are cold pressed from steel. To get rid of their sharp edges, the parts go into a rotary drum with ceramic particles. To improve their service life and their conductivity, the mass and center electrodes are increasingly assigned a copper heart. The electrodes then receive a durable jacket made of nickel alloy. At the wedding between the parts, a conductive glass mass serves as a welding agent that also provides the gas-tight seal between the parts. This phase is done on the conveyor in a continuous oven.
Exotic
The metal body parts of the spark plugs are also cold pressed and have bar material as their origin. In six fully automatic working steps, a piece of rod material turns into a steel spark plug body. That semi-finished product is then turned to size and is provided with its internal crimping edge in a difficulty. After the ground electrode has been welded on, the thread is rolled up cold and the ground electrode is bent. Beru currently has spark plugs with up to 4 mass electrodes in production. Everything of course in favor of optimum combustion! It is clear that classic spark plugs are generally less exotic. After the lettering has been applied to the metal, it is given a galvanic treatment in a nickel bath.
The nickel layer provides protection against wear and protects the surface. The parts are finally pressed together on the assembly line - with another inner seal. The shrink edge is briefly but vigorously heated and crushed. The shrinkage occurring during the cooling process ensures an absolutely secure connection between the insulator and the metal spark plug body part. After the sealing ring has been pressed into place, the electrode distance is automatically adjusted. Then there is a visual check. Then the spark plugs go on a world tour in their boxes.
The miracle spark plugs
Splitfire, Halo, Pulsstar Power Plugs… They all promise more power and less consumption due to a much better and hotter spark. That was clear with a test device from such a supplier. Until we got hold of such a test / comparison box and opened it. The 'normal' good spark plug was fed by an ordinary high voltage coil. The super spark plug got its food from another coil that delivered much higher power. That explained the difference in spark size. Nice is not it? Three side electrodes or a ring electrode as a ground electrode? The spark really only skips at one point. They can't hurt those super spark plugs. And if all goes well, you will receive a nice sticker set… And those platinairidium copies? These have actually only been developed to allow the spark plugs to run in parallel with the increasingly longer service intervals. They don't necessarily spark better, they just last longer ...
Miracle spark plugs do not exist. Pulstars are fragile spark plugs, but they work a bit better than the good municipality of competitors. The price, on the other hand, does not cooperate.
Electrode distances and the upstream 'power plant' determine the spark power. With poorly set mixes, a high spark capacity is necessary for a successful flop and anyway for the general engine and emission performance.
Electrode distances that have become too large often cause stick coils to die. Keeping the distance well below the maximum is important.
The multi-electrode spark plugs are only useful if there is something wrong with the mixture to be ignited. In other words, if there is something unconsciously or consciously "wrong" in terms of fuel, then the ignition can still take place by means of a multiple spark plug electrodes. The Irridium spark plug certainly has more advantages than just a longer life. The high voltage required to ignite is on average 5Kvolt lower compared to a conventional spark plug. That is why they are also offered as “LPG” spark plug. With a Denso Irridium spark plug, for example, the chance of ignition is many times greater and in, for example, a classic there is less chance of breaking the hood, rotor and cables due to a lower required voltage.
Thank you for this addition!
The spark plug with 2 or 3 ground electrodes is not that strange and certainly not a “sales pitch”.
The spark finds its way along the least resistance and if there is only 1 way it stops, but with 2 or 3 it jumps over the least resistance and the engine can indeed run “a little” nicer.
It will not be immediately noticeable in Opa, s Corsa, but in the current with very nervous engine management computers.
Toyota already had models with double electrodes in the 80s in certain models, including the leanburn engine that was also very sensitive to combustion.
Thank you for this addition. So let the approach be “it can help, but there are no miracle spark plugs”.