Spark plugs are a key part of any gasoline vehicle.
Below, we have compiled some key facts and information about spark plugs and gathered 10 of the best spark plugs on the market for you to have a look through.
Table of Contents
- The Invention of the Spark Plug
- What is a Spark Plug?
- What Can Go Wrong?
- What Causes Misfires?
- Why Would You Replace Your Spark Plugs?
- To Replace Your Spark Plugs, You Will Need:
- Ordering the Correct Spark Plugs For Your Vehicle
- View The Best Spark Plugs Below
- 1. NGK
- 2. Bosch
- 3. Champion
- 4. ACDelco
- 5. Motorcraft
- 6. Denso
- 7. Autolite
- 8. E3
- Spark Plugs Buyers Guide
The Invention of the Spark Plug
In the late 1800s and early 1900s, ignition was one of the most difficult problems for automotive manufacturers. The best method they used was the glow tube ignition system, invented by Gottlieb Daimler, but it created a constant fire hazard. Other possibilities included a battery ignition system, but as alternators had not yet been developed, this restricted the vehicle’s range to a few miles at best – not very far at all.
In 1897, Bosch’s factory manager, Arnold Zahringer, patented the first magneto. This was an early version of the spark plug. However, it was complicated – it needed to be redesigned for every engine and was prone to breaking. Following this, in 1901, Bosch came up with the first spark plug.
They patented it in 1902. This was the first time a product with a timed spark across two electrodes to ignite fuel in an internal combustion engine had been invented. Big names, such as Kart Benz, had experimented with it before this time. However, there hasn’t been any success until now. From then until now, the spark plug was updated and refined to make it more durable and efficient.
What is a Spark Plug?
In short, spark plugs are what makes a vehicle’s engine work. The plug is made from metal, with a ceramic exterior to prevent the electrical charge from shorting out before the spark is produced. A charge passes through the plug, jumping across the “gap” at its base. This action causes a spark, hence the name “spark plug.”
This spark then ignites the fuel and air mixture inside the engine’s cylinder, forcing the piston inside the cylinder down. This causes the crankshaft at the base of the engine – where all the pistons are attached – to turn. This drives the wheels.
Spark plugs may only be used in gasoline or petrol vehicles. Diesel ignites due to extreme force compression. Therefore no spark is needed in these engines. Newer cars tend to run on things such as battery or hydrogen power, so they don’t need an iridium spark plug, or a cooper or platinum spark plug – all their power comes straight from the source to the wheels.
The best car spark plugs are built to withstand extreme pressures and temperatures that get inside your engines, such as 5 MPa and 1000 degrees Celsius, as many fuel deposits as possible are burnt off by the engine.
What Can Go Wrong?
Problems arise when your gasoline engine develops a “misfire” in one of the cylinders. A misfire is simply when that particular cylinder’s spark plug is not sparking, and therefore the fuel is not igniting. Therefore, there’s no power going to the engine from that particular cylinder. This results in a loss of performance, which can also damage the engine and cause worse fuel efficiency.
You can spot misfires by a dramatic drop in power. Often, if only one or two cylinders are misfiring, the engine will continue to run, albeit with a weak performance and fuel efficiency. If three or more cylinders are constantly misfiring, then the engine is likely to stall and not run at all.
Other obvious symptoms involve shaking, especially the gear stick inside the cockpit. When you open the hood, the engine block itself may look like it’s throwing itself around and vibrating more than usual. Both of these are due to the imbalanced forces occurring in the engine. This is due to one or more cylinders that are not firing.
When spark plugs need replacing, you might notice:
· Reduced performance
· Reduced fuel efficiency
. Unusual noises from the engine, such as rattles, knocks, and pings
· Starting the car may take longer or sound louder than usual
Never be afraid to take your vehicle to your mechanic if you’re not sure about something. It’s their job to investigate the problem, and it’s always best to be safe than sorry!
What Causes Misfires?
Misfires can be caused by a variety of things. Most often, the spark plugs are simply old, broken, or they may be caked up with fuel deposits from the engine, and therefore aren’t working or have a low performance. The gap could have expanded on the spark plugs due to the very high temperatures and debris in the engine, which over time, cause the gap to increase slightly. As you can imagine, if the electrical charge has to cross a greater gap, it won’t be as efficient, or it might not work at all, therefore causing the misfire.
Occasionally the misfire could be caused by something more complicated, such as an ignition coil, which is what sends the electrical charge to the spark plug. In this case, that would also need to be replaced. If you have a multimeter or other similar electrical testing equipment, you can use this to check all the coil packs. If these are all fine, you’ll likely need to change the spark plugs. There’s no real way to know if changing them will fix your problem until you have actually done it and run the engine.
Why Would You Replace Your Spark Plugs?
So why would you consider replacing your spark plugs?
Well, first of all, replacing your spark plugs will ensure that your vehicle is running at good performance. Engines require a little Tender Loving Care to keep them ticking over smoothly. New spark plugs will give you not only a good performance but also the best peace of mind possible that you’re burning fuel in the best, most efficient way. New plugs also maximize fuel economy.
Some studies suggest that the best spark plugs can reduce fuel consumption by up to 30%, so changing the spark plugs could save you a chunk of gas money, as well as ensuring that you’re looking after your vehicle properly. At the same time, new spark plugs will result in smoother fuel-burning, helping to protect the environment.
However, you’ll notice the biggest change of all when starting your car. Old spark plugs may make your vehicle struggle to start, particularly on cold mornings. New spark plugs will completely do away with that, provided there are no other issues with the engine.
This includes the battery, alternator, coil packs or fuel injectors, and the carburetor. The first time you start your car after having replaced the spark plugs can be a truly eye-opening experience, as you might not realize how much of a difference a new set of spark plugs will make.
To Replace Your Spark Plugs, You Will Need:
To change your spark plugs, you may need a ratchet, an extension for the ratchet, and a spark plug socket of the correct size. They can be obtained from any automotive hardware store. Spark plug sockets have a specially designed rubber flap in them, which grips the plug and pulls it up out of the engine.
You’ll find that a normal deep socket of the correct size will do the job of loosening or tightening the spark plugs, but you’ll then struggle to remove the plug from the engine without a magnet of some sort – you may need a magnet, and these are also available in hardware stores.
When you’re replacing your spark plugs, be careful not to touch the ceramic part. The ceramic around the spark plug should be protected by some sort of card or plastic cylindrical covering. Use this to handle the spark plug and be very careful not to drop or damage the plug in any way, in particular the ceramic section.
The reason for this is because the ceramic acts as an electrical insulator, preventing the charge from shorting onto the engine block. If the charge was to shorten onto the engine block, then it wouldn’t reach the electrodes at the tip of the spark plug. Therefore, no type of spark would be made.
If you were to damage the ceramic part of the plug, then it wouldn’t act as an electrical insulator so well, and therefore the spark plug would not work at all. This is the last thing you’ll want after having gone through all the effort to change the spark plug!
You may be able to adjust the gap on your spark plug, or sometimes they’re sold with a fixed gap. Always make sure that this gap on your new plug also matches the distance mentioned in the owner’s manual. These gaps are usually around about 1mm. If the gaps are adjustable, then make sure they’re adjusted to the correct distance. If the gaps on the spark plug you’re looking at is fixed but different to what the manual recommends, then find some different plugs.
Ordering the Correct Spark Plugs For Your Vehicle
Important: each vehicle has an engine designed for a specific size and type of spark plug. You can’t just buy any type of spark plug for your vehicle – spark plugs all have different electrode gaps, insulator properties, metallic components, hex sizes, and so on. They also come with different materials, such as copper, platinum, or you can get an iridium spark plug.
You’ll find the spark plug specifications in your owner’s manual. If you’re in any doubt, give your vehicle information to the store or mechanic, who’ll make sure that you get the right parts for your vehicle. If you order the wrong parts, then the car will suffer from poor performance, or it might not start at all. Or, quite simply, the spark plugs won’t even fit into the engine.
With this in mind, if you’re thinking of replacing your spark plugs for the best performance, or even just browsing what’s available, we’ve come up with a selection of top-quality spark plugs available on Amazon. Before ordering a spark plug, please ensure that they will fit your vehicle.
View The Best Spark Plugs Below
Without a doubt, one of the world’s leading companies in the field, NGK Spark Plugs, was set up in 1936. After years of development, NGK branched out into producing oxygen sensors (also known as lambda sensors) in 1982, and glow plugs (for diesel engines) in 1985. Through the following years, its products were honed and advanced, making NGK one of the most trusted names out there for both iridium and platinum spark plugs.
Here are a couple of examples of their iridium and platinum products.
NGK 6046 PK2 DCPR7EIX Iridium IX Spark Plugs
NGK 7090 G-Power Platinum Spark Plugs
NGK BKR5E-11 V-Power
Bosch is the oldest name in the history of spark plugs (see “The Invention of the Spark Plug”). Bosch was the first company to invent the spark plug in 1902. This replaced what was previously used at those times: glow tubes and naked flames. Bosch has been making spark plugs since their first factory opened in 1914, and have since been constantly researching and developing their products.
To this date, Bosch has produced over 20,000 different types of spark plugs, ranging from platinum spark plugs to iridium spark plugs. It currently manufactures more than 350,000,000 spark plugs every year, securing its status as a brand traditionally associated with making the best spark plugs.
Bosch is particularly associated with quality and performance, as one of the oldest and first producer of spark plugs. It’s well known in the motorsport world – the top competing teams often use Bosch spark plugs. Notably, the last 17 Indy500 winners all used Bosch spark plugs in their vehicles. If that’s not a sign of durability, quality, and high performance, we don’t know what is.
Bosch produces all types of plugs. Its iridium spark plugs, in particular, are well-known for performance and reliability. Here is a couple you can find on Amazon:
Bosch Automotive 9603 Double Iridium Spark Plugs
Champion was founded in 1908 in Boston and moved to Ohio in 1910 to be closer to the Willys-Overland Auto Company. It’s been producing spark plugs ever since. Its current line includes one of the widest available ranges of different spark plugs for all sorts of vehicles from iridium spark plugs to platinum spark plugs.
It also produces other different kinds of automotive maintenance equipment, such as glow plugs, wiper blades and oil filters, amongst others. To try to boost their reputation in the late 1920s and early 1930s, Champion sponsored a music radio show called Champion Spark Plug Hour, which was broadcasted from New York.
Here’s an example of one of its spark plugs:
Champion RC12YC Spark Plugs
ACDelco is an American company owned by GM (General Motors). When GM manufacture their vehicles, it uses ACDelco parts. ACDelco also produces aftermarket parts for vehicles produced by companies other than GM. It was founded in 1916 by William Durant, the owner of Buick and founder of Chevrolet after he bought his way back into GM.
ACDelco’s spark plugs, as of all its parts, are all made to OE specifications. An example of one of their iridium spark plug:
ACDelco 41-993 Iridium Spark Plugs
Motorcraft is Ford Motor Company’s auto parts brand. It still designs and makes parts for Lincoln, Ford, and Mercury vehicles. The company was originally launched in the 1950s but was disbanded when Ford began using the brand Autolite for their parts (see Autolite). In its current state, the company has been running since 1972.
As with most markets on this list, all of the best spark plugs are made to OE specifications. If you want to get the best spark plug for your vehicle, you can find an example of Motorcraft’s platinum products on Amazon here:
AD Auto Parts OEM Finewire Platinum Spark Plugs
In Japan, Denso became separate from Toyota in 1949 and set up as its own company. However, around 25% of it is still owned by the Japanese motor giant. In 2016, it was the fourth-largest auto-supplier in the world. The name Denso is a blend of the Japanese words for “electricity” and “device.”
It has supplied many parts for Toyota’s production vehicles as well as racing ventures, including Toyota’s old Formula 1 team, its WRC team, and its FIA World Endurance Team, which vouches for the high levels of performance of their products.
Here are a couple of its products:
Denso SK20R11 Iridium Spark Plugs
Autolite is an American brand that makes spark plugs and ignition coils, founded in 1911, to produce early day buggy lamps. In 1927 it began producing automotive batteries and, in 1935, entered the spark plug market.
As mentioned previously (see Motorcraft), it was bought by Ford in 1961 remained under Ford’s name until a federal lawsuit forced them to sell the company to the Bendix Corporation by 1973. It has been producing the official spark plug of NASCAR since the year 2000.
You can buy some of Autolite’s products here:
Autolite AP5263-4PK Platinum Spark Plugs
E3 is a relatively new spark plug company, having invested a lot of research and development into developing a more environmentally friendly spark plug. It claims that their sparks offer some of the most efficient burnings of fuel available in today’s market. The Environmental Protection Agency reported that there were “clear advantages in hydrocarbon and carbon monoxide emissions control while at the same time improving power and fuel economy” (https://e3sparkplugs.com/blog/e3s-history-making-spark-plugs/) when using E3’s plugs.
You can find some of their plugs here:
E3 Spark Plug E3.36 Powersports Spark Plugs
Spark Plugs Buyers Guide
Price or Quality?
When looking for spark plugs, we would always suggest prioritizing quality over price. You will almost always find that quality spark plugs last much, much longer than cheaper ones, and this will cancel out the extra amount you paid for them. We would recommend avoiding dirt-cheap spark plugs – there’s a reason for the price, and they will almost certainly cause more harm than good!
Do New Spark Plugs Add Horsepower?
Well, yes and no. Adding new spark plugs helps the engine restore some horsepower, which it might have lost due to old spark plugs. The best spark plugs may add a slight amount of horsepower to your engine if they’re more efficient at burning the fuel and air mixture than the manufacturer-installed plugs. Even this, though, will result in a maximum power increase of up to 1-2%.
Which Types of Spark Plugs Should I Get?
The best spark plugs will last about 20,000 miles -30,000 miles, provided the vehicle isn’t driven harshly. A quick look at the owner’s manual or service sheet should inform you if the spark plugs are due for renewal, and whether or not you can feel a misfire. It’s always better to avoid the problem than have to fix it. How often you need to replace the spark plug, though, would depend on what plugs have been installed.
A common question to ask would be wondering whether spark plugs made of precious metals such as iridium are worth it. In our opinion, yes. A premium iridium spark plug gives better fuel efficiency over a much longer-lasting life. They will cost you a bit more upfront, but over time you will almost certainly save money due to not having to replace them as often.
As mentioned earlier, plugs with a copper core tend not to last very long, whereas ones made from precious metals such as platinum or iridium spark plugs can last four times as long as a standard plug with a copper core. That’s something worth bearing in mind.
It’s often a good idea to get at least the same plugs as were originally fitted by the manufacturer. This is provided the vehicle has not had any engine modifications such as a new chip or forced induction kit (a turbocharger or supercharger) being added in an aftermarket job.
Alternatively, you could choose to upgrade your plugs to a more premium plug. You don’t want a plug, be that iridium or copper, that will last less than 20,000 miles – that’ll make for poor performance.
Things to Bear in Mind When Changing Plugs
How complicated is it to change your spark plugs? Well, it can range – from extremely simple to soul-crushingly, painfully tricky. This is entirely dependent on how the manufacturer has designed the vehicle, but, as a general rule, follow this advice:
· Inline engines (usually four or six cylinders) – easy. The spark plugs can be easily accessed from the top of the engine by taking the cover off and removing the coil packs.
· V-engines (usually six or eight cylinders) – are often tricky. This is due to the plugs being at an angle, and sometimes difficult to access.
· Flat/boxer engines (usually four cylinders) – very tricky. In these engines, the spark plug needs to be accessed from the side, horizontally. This is because of the nature of the engines. If you’re preparing to change the plugs yourself on one of these engines (usually found on Subarus and Porsches), we would suggest watching or reading a “how-to” guide for your particular model. It might save you at least some bruised knuckles.
When changing spark plugs, allow anything from 20 minutes to 6 hours for the more difficult engines.
Changing spark plugs must always be done when the engine is reasonably cold, quite simply so that you, or your mechanic, don’t burn themselves on the hot parts you’re working with. Metal also slightly expands when it’s warm, so fitting cold plugs to a warm engine may result in an inefficient fit.
If you’re changing the plugs yourself, always make sure that you tighten the spark plugs tightly, but not too tight. Always follow the recommended torque settings, which you can find in the owner’s manual, or by entering your vehicle’s details online. The last thing you want is for a plug to snap off in the engine. That can be quite difficult to fix.
Overall, the best spark plug for you will depend on what you’re after for your vehicle. The brands we’ve looked at all offer high quality, manufacturer specification products, excellent performance, and all come with a good reputation.
Most importantly, as mentioned before, when purchasing online, make sure that the spark plugs fit your vehicle! We hope this article has been useful and will help you to make the most of your spark plug shopping.
- NGK 7090 Spark Plug - Pack of 4 (7090)