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TaKaI RTYPE Spark Plugs - Series I / II

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One last technical thread and information on our R-TYPE spark plug lineup.

The SERIES 1 and SERIES 2 spark plugs are designed for high performance and extended service life. The SERIES 2 will never need replacement for the life of the engine.

For some technical information


The largest mis-conseption in the industry is that because copper is a better conductor than Iridium somehow it is somehow superior on a spark plug electrode. The industry is full of mis-information when it comes to spark plug center electrode design and this is one of the biggest of them all. While copper is superior in pure conduction capabilities, it does not form the electrode on any spark plug due to the hardness characteristics required to prevent erosion in the spark gap. Typically these "copper" spark plugs use a nickle based center electrode which is a much worse conductor then Iridium.

Also, when designing a spark plug the criteria is not to conduct electricity, it is to ionize the spark gap. A majority of the electrical energy is wasted creating the initial spark when it could be used to maintain and initiate the spark across the spark gap. In this scenario a smaller center electrode usually makes a better spark plug since it requires less voltage to ionize and create a spark. Even though a smaller center electrode fires with less voltage requirements then a typical copper spark plug there are many other things to take into concideration in the development of tip size.

For example, a center electrode with a very small diameter 0.1mm will prove to deteriorate very rapidly. A 0.4mm body is fast approaching the limits of this phenomenon while a 0.6mm iridium tip is well within the safe area for long term operation.

Finding a well balanced tip design is fundamental for creating a spark plug that has a long, high performance service life. In this documentation TaKaI has recorded how the optimal tip size for thier 360degree laser welded Iridium tip was found.

In back to back comparisons of a 0.4 / 0.5 and 0.6 tip diameter the voltage required to fire the spark plug are all almost identical. Only when you take a spark plug with a common size center electrode (such as a copper or standard style spark plug) does the voltage requirement increase to a point where there is a compromise in power output. (see spark_gap.jpg)

In addition, electrons are emitted where the electrical field strength is greatest, this is from wherever the radius of curvature of the surface is smallest, for example, from a sharp point or edge. It would be easiest to pull electrons from a pointed electrode but a pointed electrode would erode after only a few seconds. Instead, the electrons emit from the sharp edges of the end of the electrode and as these edges erode, the spark becomes weaker and less reliable. If electricity prefers to jump from a smaller edge which spark plug design would be considered superior? Copper simply cannot be made smaller because of it's poor resistance to erosion. The Iridium design wins in 2 areas. The voltage requirement for Iridium is much less and the electrode can withstand erosion due to it's properties.


See servicelife.jpg

In tests using a high power ignition system. With a 0.4mm center electrode the threshold at which ground strap degrdation rapidly increases since there is not enough surface area on the tip to equally distribute the spark along the ground strap. This effectively causes rapid deterioration on a small area directly under the spark center electrode. This, in turn, causes failure of a high output spark through the service life of the spark plug. Soon after failure of the spark plug, misfire events, engine horsepower loss and compromised gas mileage follow.

Using a 0.5mm or 0.6mm center electrode rapid deterioration is not an issue giving the spark plug center electrode just enough outer diameter for a long life span with a high quality spark output. Even after 400 hours of use they are both outputting a more accurate and intense spark than the 0.4mm after just 200 hours. Clearly, the advantage starts to make itself known. 0.5mm offers the best potential of both worlds.

Iridium electrode design is over 2000x harder then typical electrode designs allowing for the development of precious metal high temperature electrodes which allows for the use of a smaller center wire, which has sharper edges but will not melt or corrode away. The smaller electrode also absorbs less heat from the spark and initial flame energy allowing for a further enhanced output. This allows the Iridium design to outperform conventional copper plug designs for over 60,000 miles of use with our SERIES I RTYPE spark plugs and over 500,000 miles with our SERIES II RTYPE spark plugs.


See ignite.jpg

Ignitability is a measure of how effectively and efficiently a spark plug can ignite the air fuel mixture in the combustion chamber. The best way to measure ignitability is to lean out the air/fuel mixture until misfire occurs. This is because lean mixtures are difficult to ignite. This gives engineers an indication of which spark tip style will gives better overall ignitability characteristics. These characteristics allow spark plugs to perform better under normal operation. The end result is more power, lower emissions and higher efficiency of the ignition system. Spark plugs with a smaller center electrode diameter offer better ignitability results.

A standard spark plug's center electrode of 2.5mm diameter has more than 15 times the surface area of a fine wire center electrode. You can see that moving from a standard 2.5mm electrode plug to a fine wire plug results in a dramatic improvement in ignitability.

During testing, limits to improving ignitability using a reduction in center electrode diameter are finite. Infact, past about 0.5mm the curve starts to flatten meaning that going to a 0.4 or finer electrode will yield almost no positive results especially since the 0.4mm center electrode has a tendency to deteriorate and electrode quickly.

At this point TaKaI decided that this negligible improvement in ignitability does not compensate for the loss of performance throughout the plugs service life. The 0.5mm fine wire electrode is superior to all others.

GROUND ELECTRODE DESIGN – further increasing ignitability

The ground electrode strap is a key area of spark plug development. The TaKaI MX groove is a new concept that increases area for flame front propagation through slotting the ground strap. This along with the tapered style ground electrodes holds tolerance over time and offers long service life and performance enhancements through reduced flame quenching and improved flame front propegation in our SERIES I spark plugs.

Our SERIES II spark plugs further enhance this phenomenon by using a fine wire center and side gap electrodes which opens the flame front to the combustion chamber, reduces ionization voltage to it's minimum and increases the flow of the A/F mix to the spark gap. The SERIES II is also used in applications where maximum reliability and performance are required for long service life intervals such as airplane applications where misfire events need to be held to a minimum and reliable high output performance is created over the service life of the spark plug.



see gap.jpg

TaKaI has designed the SERIES I and SERIES II RTYPE spark plugs with high output in mind. Since TaKaI spark plugs are classified differently then our competitions we do not have to follow FCC guidelines for noise emissions which mandates the use of a "resistor" style spark plug. TaKaI RTYPE spark plugs are classified as non-resistor in applications that are optimal for them and offer a lower internal resistance than competitor iridium spark plugs.

Federal guidlines for FCC noise supression mandate that all street driven vehicle spark plugs must adhere to standards that effectivly reduce the power output of the spark plugs. Typical street oriented spark plugs reduce power output by using internal resistances ranging from 5000 to 10,000 ohms compromising spark energy. By reducing internal resitance in the circuit spark output and ignitability characteristics increase above and beyond the competitions design by increasing the power at the spark gap.

Since the TaKaI RTYPE design uses less resistance in the ignition circuit energy is saved while the spark is initiated in the gap. This allows for higher current, longer spark on time and increased power at the spark gap.


The fact is, engines NEED a hotter spark for a more complete, higher horsepower combustion event. A small spark can only release an equivalent amount of energy in another process such as starting a large flame kernel in the combustion chamber. This is why it is also critical to increase available spark output. By increasing spark output more energy per combustion event can then be released by the spark itself. So what is needed to realize the full potential from an engine are the TaKaI RTYPE spark plugs which excel over other designs in increasing spark energy.

spark gap.jpg






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