With a couple of exceptions, platinum plugs use a conventional electrode configuration with a small platinum plug welded to the tip of the center electrode (single platinum) or the tip of the center electrode and ground electrode (double platinum). ACDelco also offers a platinum version of its "Rapidfire" plug that features a fluted center electrode for improved ignition reliability. Likewise, Split-Fire offers a platinum version of its split electrode plugs for motorists who want extended life as well as reduced misfiring. By comparison, iridium plugs have a small wire center electrode, and like platinum plugs may be single iridium (center electrode only) or double iridium (center and ground electrodes).
The latest development in spark plug technology is Ruthenium Spark Plugs. Electrodes made of a special ruthenium alloy are said to last 2X longer than current iridium spark plugs, and 4X longer than standard nickel electrode spark plugs. The increased wear resistance of the electrodes means these plugs may truly become "lifetime" spark plugs that never need to be replaced. They are also said to offer better ignitability for improved performance, emissions, fuel economy and acceleration.
Choosing Racing Spark Plugs
Selecting the proper spark plugs for a performance engine can mean the difference between front of the pack and not finishing the race. When using this guide, understand that race plugs are usually of a much colder heat range rating than standard automotive spark plugs. Colder spark plugs must be used in engines with increased cylinder pressures, higher temperatures and greater horsepower. Other factors such as fuel delivery (turbo, supercharged), fuel types and piston-to-head clearance will also affect proper plug selection.
Step 1: Shell Design - The first step in choosing the proper race spark plug is determining the plug type that your cylinder head/piston will accept. Thread diameter and pitch, thread length and shell seat, as well as hex size are all factors that will define what shell type works best for your engine.
Step 2: Electrode Design - The second decision is electrode design and configuration. Is it a fine wire center or standard electrode? Projected or non-projected? Full coverage 'J-Gap' or perhaps a cut-back or angled ground wire? A good rule of thumb is to attain as much projection into the cylinder as possible. But be aware of piston clearance that could prohibit projected spark plugs from being used.
Step 3: Heat Range - The third factor in choosing a race plug is heat range. Correct heat range is critical in maintaining peak performance throughout the duration of your race or event. Switching to a colder or hotter plug will not increase horsepower, but could affect engine performance. Choosing a plug that is too hot can result in preignition or detonation. A plug that is too cold could cause an engine to stumble, misfire or foul.
The main factors to consider in selecting the proper heat range are: type of race, methanol, specific output, nitro-meth, compression ratio, nitrous oxide, horsepower, super or turbo charging and racing fuel.
Courtesy: Champion Spark Plugs |
Spark Plug Replacement Tips
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Spark Plug Torque and Gap ![]() Spark plugs come pregapped from the factory, but because of parts consolidation the factory gap may not always the specified gap for your engine. Always refer to the specified electrode gap on your engine emissions decal. This typically ranges from .028 to .034 inches. Wider gaps are often required for leaner air/fuel mixtures, but if the gap is too wide it increases the risk of misfire when the engine is under load. On Bosch Platinum+4 and Platinum2 spark plugs, DO NOT change the factory electrode gap regardless of what the gap specification is for your engine. The Bosch plugs come with a 1.6-mm gap, which Bosch says works for ALL applications with their unique spark plug design. How much the spark plugs should be tightened depends on the size of the plugs and the type of plug seat. Spark plugs with gasket-style seats require more torque than those with taper seats. Always follow vehicle manufacturer torque recommendations, but as a general rule:
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