Denso vs NGK – Which Spark Plug Is the Better Choice?

Spark plugs have a crucial role to play in the mechanism of automobiles. A car needs good-quality and fully-functioning plugs for running the engine. There are a couple of spark plug models in the market. Two popular models are Denso and NGK, which work extremely well with all types of vehicles. But, which one will have the edge in a Denso vs NGK comparison?

About Denso Spark Plugs

Developed and marketed in 1957, Denso spark plugs are used on all vehicles, especially for racing cars. 

Denso spark plug construction includes:

  • Ceramic insulator
  • Positive electrode
  • An upper pole
  • A glass seal
  • A resistor
  • Negative electrode
  • Sealing ring

The heat transfer index of Denso spark plugs is from 9 to 37, the smaller the number, the hotter the spark plug, and vice versa.

Some features of Denso spark plugs:

  • Good electrical insulation and good thermal conductivity.
  • The cement part is made of a mixture of copper and glass, which prevents the amount of gas from burning and conducts electricity well.
  • The carbon insulation resistor helps to reduce the interference of the spark plug radio signal. Especially, the positive electrode part is made of copper core to increase the ability to conduct electricity and heat.
  • The negative electrode represents the exclusivity of the Denso spark plug, which has a U-groove to increase the spark plug’s ignition efficiency.
Denso spark plug
Developed and marketed in 1957, Denso spark plugs are used on all vehicles, especially for racing cars (Photo:

About NGK Spark Plugs

NGK is one of the leading brands in the field of manufacturing spark plugs for cars and motorcycles in the world. NGK spark plug company was founded in 1936 in Japan and now has become one of the multinational company with branches in many different countries around the world. NGK spark plugs use advanced technology and high-quality materials to produce spark plugs for different types of engines. NGK spark plug products are designed to meet the stringent requirements of auto manufacturers worldwide, ensuring the best performance and reliability for all types of engines:

  • Iridium tip ensures high durability and stable spark
  • Iridium alloy has an extremely high melting point, perfect for the high-tech, high-performance engines
  • Trivalent metal plating provides superior anti-corrosion and anti-corrosion properties
  • Outstanding acceleration, high fuel economy, and durability
  • Optimal design, technology, and performance

NGK Iridium spark plugs are a popular choice for car owners looking to enhance the performance of their vehicle’s engine. Besides the advantages, NGK spark plugs still have some limitations such as:

  • NGK Iridium spark plugs can easily corrode when used in high-humidity environments or poor-quality fuel. This can cause insufficient combustion, resulting in reduced performance and reduced spark plug lifespan.
  • More expensive: Compared with ordinary spark plugs, NGK Iridium spark plugs are more expensive. However, if you want to enhance the performance of your vehicle, this is a valuable option.
  • Unsuitable for many vehicles: NGK Iridium spark plugs are not suitable for some vehicles and engines. Before deciding on this type of spark plug, check if the spark plug is compatible with your vehicle.

Overall, NGK spark plugs are a leading brand in production. Its products are manufactured using advanced technology and high-quality materials, ensuring the efficient and reliable performance of vehicles.

Denso vs NGK: What Type of Spark Plugs Are They?

On the market, there are many types of spark plugs, but two famous and popular spark plug brands are Denso and NGK spark plugs. Compare Denso and NGK spark plugs to see what difference there is between the spark plugs of these famous brands.

Both types are iridium spark plugs. The metal is much less conductive than copper but lasts longer and works at a low temperature. It is also 4-5 times costlier than platinum.

Iridium spark plugs are not the best in terms of performance but nothing can beat their longevity. When a copper plug lasts for around 20,000 miles, the average lifespan of an iridium plug is 40,000 – 60,000 miles.

On the other hand, they are also a better option than platinum plugs in terms of consistency and longevity. Unlike the platinum models, they are stable, don’t grow gap over time, and don’t create extra stress on the ignition system. They also need less maintenance as checking their condition every 3 to 6 months is enough.

In a word, iridium spark plugs last longer than other types and their performance is better than the platinum units.

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Denso vs NGK Plug: Which One Is Better?

It is hard to pull out a winner in the NGK vs Denso debate since both are iridium spark plugs and offer almost similar performance.

Denso plugs are installed on almost every automobile model manufactured in Japan. The iridium used in them has a superior hardness. The electrode’s diameter in these plugs shrinks more than an NGK. For this reason, Denso plugs won’t last longer than NGK units but they will be better at producing powerful sparks.

denso spark plugs vs ngk
NGK plugs are cheaper and last longer. (Photo: Amazon)

On the other hand, NGK plugs will be a standard replacement for their platinum alternatives. They require less maintenance and provide a more stable and consistent performance than a Denso.

In short, regardless of the brand, according to our advice, you should choose the suitable type for your car as the manufacturer’s recommendation so that the fuel is burned out completely, thereby saving more fuel, increasing engine power, and accelerating faster also improving the lifespan of your car. 


With the passage of time, spark plugs have been developed into a much more heavy-duty component. Both Denso and NGK plugs work well with all types of vehicles – from light cars to heavy-duty pickup trucks. In this choice between Denso vs NGK, you will choose the first one if you care about the horsepower of your vehicle. It is only a fraction of a percent of the power increase, though. But, NGK should be your choice if you want a stable, long-lasting performance at a lower cost.