Taken from the net.
First things first. Spark Plugs will increase your efficency, but you are not going to feel a huge power increase regardless of the brand of plugs you choose.
Lets do a little Automotive 101 then you will understand.
Today's engines are mostly using an ignition system called DIS, (Distributorless Ignition System). The ignition system of any car equipped with Electronic Ignition or DIS is only going to use enough electricity to jump the gap in the spark plug.
For example if it only needs to push 10,000 Volts accross the gap that is all it it is going to push. Though a system may be capable of producing 20,000, 50,000, or 100,000 volts, it will only use what it needs to complete the curcuit. If you don't believe me take your car to a shop and place it on a scope and check the voltages.
The voltages will only increase as the plugs become worn or fouled from oil, fuel or soot from the combustion process.
Now having said that, why are there so many different types of plugs available for your vehicle? Well its simple its called marketing!
Let me walk this path with you so you can understand what these different types of plugs do and how they will benefit you or cause you problems, and with that, lets start with the Platinum Tipped Plugs.
Platinum tipped spark plugs are designed to last longer than the standard type plugs. This is because the Platinum is harder than the steel alloy electrode used in most standard issue plugs. The advantage with platinum plugs is that you do not have to change them as often as a standard plug. Also the spark they produce is slightly hotter than your standard plug. But the real factor is that they transfer and conduct the electricity better than a standard plug. This is also to be said for the Iridium Plugs.
The draw back is that they are not always the best choice for some ignition systems. Due to the lowered resistance in the circuit, some of today's ignition control modules may conclude there is a short to ground in the system. Some of the ignition systems have a certain set of voltage and resistance specifications programmed into their chips. If these numbers don't fall into the programmed window of specs, the computer can flag a trouble code, and send you to the shop to get it repaired, so its just a word of caution. Nothing more.
Next we go into configuration and multiple electrode plugs. Lets start with multiple electrode plugs. Because a plug has multiple electrodes does not mean the spark os going to hit all of the electrodes at the same time. These plugs were first developed in Aircraft. This is because the fuel burns at a much hotter rate and it had a tendancy to burn the electrodes off the spark plugs under severe engine conditions.
When a spark plug fires it heats the ground electrode every time it sparks. The metal can become fatiuged or start to melt away. When this occurs the gap opens up to a point where the plug may not fire reliably, so to handle that an extra electrode was added to share the load. Huh???
The spark will always jump to the coldest electrode. Why? The metal is denser at the colder electrode. So with having multiple electrodes you have a more reliable source of ignition for the air/fuel mixture in the combustion chamber.
Now we can cover configuration. Two excellent examples of this are the Nippondenso U-Groove Plugs and the NGK V-Power Plugs. Both of which your car was probably equipped with from the factory.
In this plug the engineers have re-configured the shape of the electrode to create a "Wide Path" spark. In other words a spark that has more surface area for the air/fuel mixture to start the burning process. These plugs, though considered a standard plug do indeed provide better ignition. Though not through a hotter spark, but through a larger one. This also does not mean it takes more juice to create that spark, it just means the configuration of the spark produces a more efficent combustion process with a larger ignition flame front.
Now we get to the final part of your question, brands!
The rule of thumb we use in the field is as follows:
Asian Production Vehicles:
Bosch
NGK
Nippondenso
American Production Vehicles:
AC Delco, (GM)
Autolite, (Ford/Chrysler)
Champion, (Chrysler)
European Production Vehicles:
NGK
Bosch
The reason for this is because of the way the ignition systems are developed. Ameican Ignition Systems are developed around, Autolite/Motorcraft, AC Delco or Champion plugs.
Asian Systems are normally developed around: Bosch, NGK or Nippondenso.
Likewise the European Systems are normally NGK or Bosch.
I own both GM cars and Toyotas, and because I have been turning wrenches for a couple of years, I have seen some strange ignition problems from using AC Delco plugs in Asian Products and vice-versa.
Some of the other folks are not going to agree with the whole plug issue, but they are going to have a hard time proving different on the facts of how an ignition system actually works.
Just keep in mind that you should really change the plugs out about every two years, regardless of type or brand. That is the best way to keep your power and fuel milage at its peak. Don't forget the air filter and your oil changes, those are equally important!
---------- Post added 10-24-2013 at 02:17 AM ---------- 6 hour anti-bump limit - Previous post was 10-23-2013 at 11:58 PM ----------
Denso Iridium Power Spark Plugs
One of the main benefits of using iridium in spark plugs is its extremely high melting point - nearly 2500ºC. The Denso Iridium Power spark plug takes full advantage of this fact by using a fine-tipped 0.4 mm diameter electrode in place of the more traditional wide-diameter offerings. A standard electrode of that diameter would more than likely melt after prolonged use, but the Iridium allows for a more precise, controlled spark-to-ignition process. Combined with Denso's exclusive U-Groove pattern ground electrode, this allows the Iridium Power to handily outperform its competitors. However, this performance comes with a premium price tag - at more than three times the price of a standard spark plug, it's hard to make a case for the average, casual driver. If you are a performance enthusiast or a long-distance commuter, the cleaner burning capability and potential for increased fuel economy with the Denso Iridium Power may be worth looking into.
NGK Iridium IX Spark Plug
You'll find NGK spark plugs under the hood of many cars as they leave the factory, which shows just how well these spark plugs perform. The Iridium IX spark plug are practically maintenance-free, and reliably ignite fuel/air mixtures within the engine. Unfortunately, these spark plugs are pricier than the alternatives.
