Put a little spark into your engine performance
The right plugs can mean better power and fuel economy, writes Brian Turner.
If you’re a fan of improved fuel economy and engine performance (and who isn’t) you’ve probably stopped at the shelves of spark plugs at your favourite auto parts store and tried to sort out what would be best for your ride from the amazingly large selection.
You’ll find copper-core, singleand dual-tipped platinum, and iridium types, with or without traditional electrodes, gap-less, and many more. All will be available in a wide variety of heat ranges and sizes. But what is right for your vehicle?
First, understand that the spark plug is only one part of a multi-component system and a very limited part at that. Its only job is to provide a clear, hot, blue spark when its electrical circuit is completed to fire the fuel-air mix at the top of the piston. Efficient and effective combustion is key to rated fuel economy and performance figures, so automakers carefully choose their spark plugs to work in conjunction with the rest of their ignition systems. Therefore going with a hotter heat range isn’t likely to improve anything.
Copper-core plugs date back to almost the beginning of the internal combustion engine and are still used in a wide variety of vehicles today. Their main drawback is their limited lifespan, requiring replacement in the 40,000- to 50,000-kilometre range. This can also be a plus because, if an owner follows the carmaker’s schedule, these plugs seldom seize in cylinder heads. They are also the cheapest, averaging between $5 and $10 each.
Iridium plugs can cost only a few dollars more than copper core but last much longer. Some have successfully passed the 100,000-km mark with little wear. As any spark plug ages, its electrode gap gets wider, making it harder to get a clean, hot spark. While they may last longer, to avoid having them seize in their threaded holes and possibly break upon removal, iridiums should be pulled every 50,000 km for inspection.
Platinum types have earned their status as the best spark plug on the market and are available in two types: single and double plated. With single platinum plugs, only one of its gap sides is coated in this precious metal, leaving the other untreated and subject to normal wear and tear. So the only answer is to use double platinum plugs. Some automakers went cheap and used single coated plugs that were specific to each cylinder head. If you mixed up these plugs they would only have the lifespan of the lowly copper core type. Platinum plugs are also the most expensive, ranging from $15-$30 each and still need to be pulled every 50,000 km to avoid seizing.
Of all the mistakes one can make in selecting a spark plug, sizing can be the most expensive. Install a plug that extends too far into the combustion chamber and you risk some severe piston and cylinder-wall damage when the plug comes into contact with the head of the piston.