If you have a vehicle, you have spark plugs, and it’s important that you know which are best for your specific car or truck. The job of your spark plugs is to deliver an electric current from the ignition to the combustion chamber, which ignites the fuel/air mixture using an electric spark.
They look quite small to the eye, but are very important to the overall operation of your vehicle. Spark plugs must be well-made and able to withstand a lot of pressure, and they are used every time you run your vehicle. On top of that, they are used multiple times during your travels, so they often need to be replaced.
At first glance, these spark plugs from Denso look like any other spark plug on the market, though the appearance is a bit different because it is shiny thanks to the iridium, and they just look new because they doesn’t have the coppery appearance that you might see on other spark plugs made of platinum.
The packaging of iridium spark plugs Denso is simple; it comes in a small, cardboard box. You get four pieces, and each piece comes in its own box. All four boxes fit into a larger box, making it convenient to keep everything together and organized until you are ready to install the spark plugs into your vehicle.
The Denso spark plug uses the 360-degree laser-welding process with iridium. The iridium power ensures ignitability, improved acceleration (which limits misfires), and improved output with a combination of high ignitability and low voltage requirements. You don’t always get this type of performance with spark plugs that are made of other metals.
The voltage requirements are reduced as firing performance improves, too, which adds to the performance value of these spark plugs.
Users can get a longer life from the Denso spark plug, too, up to 63,000 miles. You can also see improved fuel economy (up to five percent in most cases).
Advantages/Functionality/The main differences
The Denso spark plug (Iridium) can minimize heat loss, and the smaller electrode diameter can improve ignitability.
While it is more expensive, compared to other spark plugs out there, you can purchase a four-pack, which can save you some money as you are buying in bulk. Plus, you never know when you might need to replace a spark plug in your vehicle, so it’s always good to have some available when you need them.
Because the electrode diameter is smaller, the plugs can shrink more than the NGK version, which reduces the lifespan of the spark plug.
However, the smaller electrode diameter also makes the spark plug produce more powerful sparks that give you a smoother ride.
Is This Product Recommended?
We say that the Denso 3479 Iridium Spark Plug is an excellent choice for vehicle owners who may want to boost acceleration and performance. While anyone can enjoy getting up to full speed faster, those who have race-cars or wish to race may particularly enjoy the fact that they can get better performance and accelerate faster just by changing out the spark plugs they currently use with this one.
What the Customers Say
No customer had any complaints about the product. As long as you select your vehicle to ensure that it fits, you won’t have any troubles when it comes to installing these spark plugs.
Most people mentioned that they work just as they are advertised to do and last as long, or even longer, as claimed. Plus, many consumers have solved hesitation and stumbling problems in low gears just by using these spark plugs instead of the ones they normally would use.
NGK IX Iridium spark plugs are manufactured using the latest technology to fit modern vehicles and those of the future. NGK also manufactures A/F sensors, spark plugs, and oxygen sensors for imported and domestic US vehicles.
The fine iridium tip maintains a stable spark, which ensures durability. The trivalent metal plating on the body ensures that it won’t corrode or seize up with time.
The insulator nose is also longer, which helps to prevent fouling. Along with such, the corrugated ribs on the insulator prevent flashover.
With this spark plug, you can see better fuel efficiency, high durability, and outstanding acceleration, which are all necessary to maximize power and maintain performance for every ride.
Because the NGK has a larger gap at .054, it takes more energy for the spark to jump between the two contact points, which could adversely affect performance, depending on the terrain and weather conditions.
- Designed specifically for the performance enthusiast, Iridium IX offers extreme ignitability, improved throttle response and superior anti fouling
- The 0.6mm laser welded fine Iridium tip ensures high durability and a consistently stable spark and the tapered ground electrode minimizes electrical Quenching Effect
- Longer insulator nose prevents fouling, the corrugated ribs on insulator prevents flashover, and a triple gasket seal eliminates combustion gas leakage
- Iridium alloy has extremely high melting point, giving it high durability to heat and electrical wear, perfect for today's high-performance engines
- Trivalent Metal Plating - superior anti-corrosion and anti-seizing properties
Is This Product Recommended?
If you want to experience faster acceleration and starting times, as well as better fuel economy, this spark plug could be right for you. You also get better ignitability than with other products, and the plugs are OEM-quality.
What the Customers Say
Most people agree that if you’re going to purchase a Japanese vehicle, you definitely need NGK spark plugs for the engine. Another market ‘rule’ is that since NGK spark plugs are more expensive, they’re definitely better and durable.
However, the biggest reason why they’re a favorite for many consumers is that they are available from a variety of retailers and can also be purchased online.
The Winner Is…
While both types of spark plugs do what they claim and most consumers have nothing but good things to say, the NGK did come out as the winner, if just by a hair.
The factors that were considered to choose the winner included pricing, what negative things the customers had to say, and the fact that Denso spark plugs claims to work for a variety of advertised vehicles and many with those vehicles had issues or couldn’t use them. NGK was less expensive, would not reduce fuel efficiency with time, and worked correctly for all vehicles it advertised.
The Bosch 9659 Double Iridium Spark Plug offers a double-iridium firing pin with ground electrode inlay, which provides up to four times as long of a service life compared to copper plugs, The 0.6mm firing pin ensures superior performance and ignitability.
The spark plug offers 360-degree continuous laser welding, which helps to fuse the corrosion-resistant firing pin to the base for more durability.
It is an original equipment replacement, which means it is designed to work well with most systems. While Iridium is the forefront, copper is used for the core, which provides better heat transfer. The fine-wire firing pin also reduces voltage requirements.
- Double Iridium firing pin and ground electrode inlay provide 4X longer service life compared to standard copper plugs
- 0.6mm fine wire firing pin provides superior ignitability and performance
- 360° continuous laser weld fuses corrosion resistant iridium firing pin to base for increased durability
- 7 year performance satisfaction guarantee
- Original equipment, pre-gapped replacement delivering optimum fit, form and function
Is This Product Recommended?
If you can find an authentic seller of authentic Bosch Double Iridium Spark Plugs, this could be an alternative to the Denso and NGK spark plugs reviewed here. However, the NGK spark plugs are slightly less expensive and provide many of the same benefits and features, such as both using iridium and both boosting performance and fuel economy.
Bosch is a manufacturer of a variety of automotive products, spark plugs, air management systems, batteries, brakes, alternators/starters, fuel pumps, filters, fuel injectors, diesel parts, and much more. It offers a variety of spark plugs, such as silver, Platinum+4, copper and nickel, double platinum, iridium, and double iridium.
The company has been setting the standard for spark plug technology since 1902, using innovative and proven products trusted by OEMs worldwide.
What Customers Are Saying
Most people rave about the Bosch Iridium spark plugs because of the seven-year guarantee. The company wants to ensure that you are satisfied and, in a sense, proves that the spark plugs are designed to last seven years without issue.
- Where are Denso Spark Plugs manufactured?
- How long do Denso Spark Plugs last?
- Are Denso plugs pre-gapped?
- Is Denso an OEM?
- Are NGK and NTK the same?
- Should I use anti-seize on NGK Spark Plugs?
- How tight should spark plugs be?
- What do the numbers on NGK Spark Plugs mean?
- Where are Bosch spark plugs made?
Where are Denso Spark Plugs manufactured?
How long do Denso Spark Plugs last?
While all spark plugs are different and those made of other materials may not last as long, Denso Iridium Spark Plugs are designed to last more than 100,000 miles with very little (or no) loss of performance.
Are Denso plugs pre-gapped?
Primarily, yes, Denso plugs leave the factories pre-gapped for many popular vehicles and applications. However, you should understand that one plug variety can fit hundreds of engines, from golf carts to vehicles. Gapping your plugs to the engine’s specifications is essential to prevent pre-detonation, fouling, pre-ignition, and poor fuel economy.
Is Denso an OEM?
In a sense, yes, Denso is an original equipment manufacturer. However, some may call Denso a supplier of OEM products rather than a manufacturer who produces original equipment. Since the 1970s, Denso has been creating aftermarket products available for Import, European, and Domestic vehicles. Because Denso supplies to OEMs that desire to use the products, Denso can be considered an OEM.
From the beginning, Dens consistently offered distributors with a variety of products for use across many models and makes, allowing for easy and quick installation, longevity, and product reliability.
Are NGK and NTK the same?
Many consumers have heard NGK referred to as NTK and may wonder if they are the same company. In a sense, they are. They have a Twins-mark, which is a symbol of both companies being reliable and trustworthy. The Twins-mark suggests that both companies have a mutual business support system and has trust between both brands, as they both uphold the same philosophies.
Should I use anti-seize on NGK Spark Plugs?
No, you should not use anti-seize with your NGK Spark Plugs. It goes against manufacturer regulations to use anti-seize products. The NGK spark plugs already have a trivalent plating. These spark plugs might have a chrome or silver finish on their threads.
This trivalent plating reduces the risk of corrosion from chemicals and moisture. It also acts like the release agent during spark plug removal. Therefore, you should install NGK spark plugs dry and without anti-seize.
Use of anti-seize can cause the installation technician to overly tighten the spark plugs. Anti-seize is designed to act as a lubricant, which affects the torque value by up to 20 percent. Using anti-seize against the manufacturer’s recommendations can be possible, though it is not recommended.
If you plan to use anti-seize, you should decrease your set torque of the torque wrench with that same amount (up to 20 percent). Otherwise, you risk breaking your spark plug, damaging the cylinder head threads of the spark plugs, or distorting the shell.
How tight should spark plugs be?
Installation recommendations are likely to differ based on the design of the spark plug. Therefore, it is best to read through the directions and installation instructions that come with the spark plug. If you aren’t sure you can do the job right, you can always take your pre-purchased spark plugs to a trusted mechanic to have them installed correctly.
Pre-gapped spark plugs usually have no issues and can be turned until they can’t be turned by hand anymore. However, some people do not know their own strength or cannot reach the spark plug area without tools, so this can be problematic.
Tapered seat spark plugs must be finger-tight, and you should always give an extra 1/16th turn with the spark plug wrench to ensure that it is tightened correctly based on the manufacturer’s recommendations.
A good formula to consider is to tighten the spark plug to about seven to 15 lb-ft of torque for 14mm threads or 15-20 lb.-ft of torque for 18mm threads, ensuring a gastight seal.
What do the numbers on NGK Spark Plugs mean?
For example, part number BKR6E-11 has a heat range of six, which would be hotter than a BKR7E-11, which indicates a heat range of seven. However, a spark plug with the part number BKR5E-11 indicates a hotter plug than the BKR6E-11 because it has a heat range number of five. If you purchase an NGK Racing Plug, the heat range number is located after the hyphen.
The first letter, in these examples, “B,” indicates the thread size, which is 14mm x 1.25 pitch. “D” letters indicate a 12mm x 1.25 pitch and “C” part numbers indicate a 10mm x 1.0 pitch. If you see a “J,” it indicates a 12mm x 1.25 pitch that includes two ground electrodes.
The second letter, in this example, “K,” indicates the wrench size (you would use a 3.8” hex. If there was a “P,” it indicates that the spark plug uses a projected tip design.
The third letter, in this example, “R,” indicates that you have a resistor type of spark plug. A “U” indicates a surface discharge gap.
The first number is the heat range, as explained earlier. The letter behind the number, in this case, “E,” indicates the length of threads on the spark plug. “E” has a 3/4″ reach while “H” indicates a 1/2″ reach.
Where are Bosch spark plugs made?
Primarily, most Bosch spark plugs are made in Germany at the Bamberg plant. Almost 8 billion spark plugs were manufactured at this plant through 2018. However, Bosch also operates a variety of plants throughout the world. These factors are located in Brazil, India, Russia, and China, and they all produce spark plugs for their local markets and automotive industries.
The alternative product produced by Bosch offers a variety of similarities, and there are some new developments soon to crop up. For one, Bosch spark plugs are an integral part of the engine system.
As such, they provide more efficient fuel consumption and cleaner combustion. They also ensure that the catalytic converter and engine is more reliable.
Significant increases in performance haven’t changed the fact that most spark plugs only stay alive for 10,000 to 20,000 miles. Of course, Iridium spark plugs can last much longer, which is an innovation that is sure to remain in the coming years.
Bosch works hard to adapt engine technology by offering spark plugs that are versatile enough to work with ultra-efficient, lean-burn, and 4-valve fuel injectors.
Denso is also focused on moving forward to new heights. The high-performance iridium center electrode presents an evolutionary apex for the spark plug. Thinner electrodes are easier to grow flames and provide more stable combustion.
Most Denso spark plugs offer the thinnest electrode on the market. It also offers a high melting point when you choose the iridium version, giving more resistance to corrosion, even when temperatures reach several thousand degrees. Compared to nickel plugs, iridium plugs have a higher capacity.
Because the automotive world is ever-changing, engine space is decreasing to make the cabin area more comfortable. Therefore, the components have to be smaller, and Denso doesn’t disappoint. The smallness doesn’t compare to the performance, which is always improving.
NGK, not to disappoint, is also looking to the future with EMEA aftermarket structuring. Currently, the company is working to launch its OE-identical (meaning it isn’t an original equipment manufacturer, but the product is similar) spark plug for the SsangYong vehicles, which is a Korean manufacturer. It guarantees a perfect ignition each time and has a 14mm thread diameter, though it has nickel ground electrodes rather than iridium.