Can spark plugs increase horsepower?

In short, yes, in some situations spark plugs can increase horsepower.

Now, before you go booking in with your local mechanic or signing your car up to the next drag event, you should know that we’re talking about power gains of maybe one to two per cent, so you’re not exactly going to be breaking any land speed records by simply ‘upgrading’ your spark plugs.

These ‘massive’ gains of one or two per cent generally won’t be exceeded, even if you’re replacing really old and worn spark plugs for new ones.

In this case, your essentially just restoring your car back to its peak performance.

The theory behind spark plugs increasing horsepower is that by providing more spark to the firing tip of the spark plug, it will (and does) combust more fuel.

However, this is negated due to modern cars being so smart and efficient that they’re already making sure that they’re burning every bit of fuel available.

This is thanks to the intelligent in-car computers and powerful ignition systems with which cars of today roll out of the factory.

So how should you choose your spark plugs?

If your car is deemed 'high-performance' from factory, it's not necessary to change to a different type of spark plug because the manufacturer will have already fitted the most appropriate type. However, if your car has since had its engine modified resulting in a changed overall compression ratio, you'll need to look at changing from stock spark plugs. 

Things that need to be considered when selecting a new type of spark plug; 

Will they efficiently remove heat generated by your engine
Will they light all the air/fuel mixture by providing efficient spark
Will they survive the added stress and heat generated by your engine
Do they achieve the desired piston-to-plug clearance

Although spark plugs can be replaced at low cost, if you’re looking to increase the horsepower in your relatively stock car, it would be worth exploring other avenues.

A performance specialist on AutoGuru can help advise you on what the next best steps are to squeeze some more ponies out of your car.

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