Can New Spark Plugs Increase Horsepower?

Spark plugs are essential components that ignite the air-fuel mixture in the combustion chamber. Without them, gasoline-powered vehicles will not combust. They achieve this by carrying high voltage electricity of the distributor or ignition coils, depending on your vehicle design.

Unfortunately, this component does not last the lifespan of the car. You’ll experience issues like bad gas mileage, improper combustion, hard starting, and reduced engine performance as they age. One of the common questions among most folks is, can new spark plugs increase horsepower since dead ones will reduce engine performance?

Here, we’ll answer this question and discuss the benefits of changing spark plugs. You’ll also learn how often you should change spark plugs and what happens if you fail to change spark plugs.

can new spark plugs increase horsepower

Can new spark plugs increase horsepower?

There are many misconceptions about whether new sparks add horsepower to cars. Some experts say spark plugs boost horsepower in cars. Others have different opinions. These people may be right only if they throw more light on what they mean.

Yes, spark plugs improve horsepower and overall engine performance. Here’s the thing; when you replace old and weak spark plugs, the engine response will significantly increase when driving.

Technically, spark plugs do not increase horsepower; they only bring the engine back to its optimal operating horsepower. New spark plugs will make a car run as if it’s new. It doesn’t add to the predefined engine horsepower.

How to choose spark plugs for my vehicle?

Choosing the right spark plugs for your car is critical for achieving peak performance, especially in high-stress situations like a drag event where power gains are crucial. The secret to optimal engine performance lies in the spark plug itself and in its compatibility with your car’s combustion chamber and ignition systems.

For a stock car, factory spark plugs are usually sufficient, designed to meet the vehicle’s specifications and provide reliable maintenance. However, the process becomes more intricate if you’re looking to improve performance. Mechanics and car computers often suggest high-performance plugs that can handle increased heat and stress, potentially leading to power gains.

Consider the firing tip and gap of the spark plugs. The gap between the firing tip and the electrode must be precise; even a bit too much or too little can affect the spark’s ability to ignite the fuel-air mixture efficiently. This is particularly important for gasoline engines as it can influence both the condition of the engine and the vehicle’s performance.

Opinions vary, and land speed records may be influenced by numerous aspects, including the choice of spark plugs. Therefore, consult with a knowledgeable mechanic who understands the theory behind the sparks that lead to combustion. This ensures that the spark plugs you choose will fit and enhance your car’s performance according to your driving needs.

How much horsepower do new spark plugs add?

Basically, spark plugs increase engine performance and horsepower back to its base level. But, If new spark plugs are bad or wrong pattern, you may face starting issue.

However, Others have different opinions stating that using upgraded spark plugs will increase your engine horsepower by at least 2%. This means that if you have a 200-horsepower engine, upgraded plugs will add an extra 4 horsepower, increasing the engine horsepower to 204 hp.

They also believe the added boost is so insignificant that you may not notice it. By this, changing your old spark plugs with high-performance spark plugs like Iridium will not offer you the desired boost.

What spark plugs make the most horsepower?

As reiterated above, new spark plugs improve engine performance and horsepower back to its base level. Here, base level means factory performance. So, we’re discussing the best spark plugs to retrieve the possible horsepower.

You may ask, do spark plugs matter, anyway? A spark plug is as vital as the overall engine power. Without it, a gasoline-powered engine will not start. The best spark plugs for better engine performance are NGK 3403 G-Power, Denso (4505) PK20TT, ACDelco 41-962, and NGK Iridium IX.

There are better spark plugs, and there are the best spark plugs. Other spark plugs help enhance overall engine performance, but the Iridium is the no.1 spark plug in the market. And the NGK Iridium IX is the best Iridium spark plug for the price.

How often should you change spark plugs?

Always follow the manufacturer’s recommendation when considering replacing any component in your vehicle. And your spark plug is no exception. However, if the vehicle owner’s manual does not specify when to replace the spark plugs, or you don’t know when last the previous owner replaced the spark plugs, then you should only replace them when you notice the symptoms of worn spark plugs.

If you have a reduced engine performance, the spark plug is the first place to look into. First, open the hood and locate the spark plugs. Then, remove the spark plugs and inspect the tips. If the plug threads or tips look dirty, you likely have oil leaks or carbon buildups.

Spark plugs that look dirty, worn, or damaged could mean the engine is operating at an excessive heat or misfiring.

Generally, you replace old spark plugs with new ones every 20,000 to 40,000 miles, depending on the spark plug you’re using, the overall engine condition, and vehicle you own.

If your vehicle uses Iridium spark plugs, it’ll last longer than the cheaper ones. It is designed to run around 80, 000 to 1,00,000 miles.

Benefits of changing spark plugs

The primary function of spark plugs is to ignite the air-fuel mixture in the combustion chambers for optimal combustion. However, it does much more than that. Here are several benefits of replacing worn spark plugs.

Optimal combustion process

Good functioning spark plugs will ignite when needed and properly burn the air-fuel mixtures in their respective cylinders. Once all the cylinders appropriately combust at the expected time, most engine performance issues will be forgotten.

Having good spark plugs all the time will not only keep engine performance at the optimal level, but it’ll also minimize engine repairs.

Improve gas mileage

According to a National Institute of Automotive Service Excellence report, driving with lousy spark plugs will cause the engine to misfire, leading to a 30% higher fuel consumption. Of course, this means more visits to the gas stations.

If the spark plugs cannot effectively ignite the air-fuel mixture, the engine will consume more fuel than expected. Undoubtedly, spark plugs get worn over time, causing performance issues and increased gas mileage. But replacing them will restore the engine to its regular settings.

iridium spark plugs hp gain

Smooth start-up

Old spark plugs will likely cause hard starting and other issues. But replacing the worn or damaged spark plugs will improve the start-up and resolve rough idling, engine misfire, and poor acceleration caused by the previous plugs.

Reduced carbon emission

According to Environmental Protection Agency, imbibing a regular maintenance culture, especially replacing worn spark plugs, reduces toxic emissions from vehicles and improves gas mileage. This is one of the spark plug benefits that will benefit the car owner and the environment at large.

Enhanced performance with premium spark plugs

Premium spark plugs with advanced materials and designs can sometimes offer some special benefits. For instance, plugs with fine-wire electrodes can provide a more focused and consistent spark, further enhancing combustion efficiency and engine performance. In certain circumstances, these plugs might contribute to a small increase in horsepower, especially in high-performance engines.

What happens if you don’t change spark plugs?

The importance of spark plugs cannot be overemphasized. We’ve outlined the importance of replacing spark plugs when necessary. But what happens if you fail to replace them when they wear out or get damaged? Then, of course, you’ll have the opposite of the benefits of replacing them. Thus, clean it regularly and replace them when worn out.

The common and most prominent effects of not replacing spark plugs when they are due are as follows.

  • Hard starting
  • Reduced gas mileage
  • Engine backfire
  • Rough idling
  • Poor acceleration
  • Engine misfire
  • Rough revs
  • Harmful emission from the tailpipes
  • Engine knocking.


New spark plugs will significantly improve the overall engine performance. Replacing worn spark plugs with high performance spark plugs will enhance the gas mileage, engine response, and horsepower. However, improving horsepower doesn’t necessarily mean adding horsepower.

At this point, you’ll no longer ask, can new spark plugs increase horsepower, or do spark plugs add horsepower? People often mistake improving horsepower with adding horsepower. The new performance spark plug improves the engine power to the factory level.

Solomon Osuagwu

Osuagwu Solomon is a vetted auto mechanic with over ten years of experience in the garage and five years of experience as a service writer. He prides himself in writing accurate information on professional repair guides, DIY repair guides, buyer’s guides, comparisons, and car reviews. If he’s not in his repair garage, he’s writing automotive blogs to help car owners and fellow mechanics to troubleshoot and proffer solutions to several car problems.

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