How Many Spark Plugs Do I Need For My Car? [It Depends On THIS]

There have been many questions about the types and number of spark plugs that every car needs. So, this article will sum up everything you need to learn regarding spark plugs.

Well, you will need several spark plugs as there are cylinders in a car’s engine. For an inline-four, inline-six, and inline-eight, you will need 4, 6, and 8 spark plugs, respectively.

However, the question you would be asking right now is, “how many spark plugs do I need?” Keep reading to find out.

What Are Spark Plugs?

Spark plugs are devices that deliver electric current coming from the ignition system to the spark-ignition engine’s combustion chamber.

This ignites the compressed air mixture or fuel through an electric spark while containing the engine’s combustion pressure.

In addition, spark plugs have a threaded metal shell, electrically isolated by a ceramic insulator from the central electrode.

These are the spark plugs’ main functions in internal combustion engines:

1. Ignites the air mixture or fuel in the combustion chamber as electrical energy is transmitted into the components.
2. Spark plugs can remove heat. The plug end’s temperature should be low enough to avoid pre-ignition. However, it should be high enough to fend off fouling.
3. Spark plugs also serve as heat exchangers by eliminating unnecessary thermal energy from the combustion chamber. And then, the heat is transferred to the engine’s cooling system.

How Many Spark Plugs Do I Need?

To answer the question, “how many spark plugs do I need?” you must first determine how many cylinders your engine has. However, some exceptions apply to those containing two spark plugs per cylinder, like HEMI engines.

V4 engine

Hot and cold are the V4 engine’s two types of spark plugs.

Hot plugs have more insulation and are usually found in standard engines. Its insulation maintains the spark plug’s temperature which burns the carbon deposits.

Meanwhile, cold plugs are ideal for high-powered engines with high horsepower and compression rates. Less insulation allows more heat transfer coming from the combustion chamber.

Also, modern car manufacturers keep an eye on fuel efficiency to decrease emissions. They do this by reducing the engine’s size and type. Almost every four-cylinder engine uses four spark plugs, one for every cylinder.

You can research the particular model, year, and make to determine if your engine contains one spark for every cylinder or check the engine bay’s displacement.

V6 engine

The V6 engine’s number of spark plugs can vary depending on the specific model and make. Other makes have dual-ignition systems and twin-spark engines.

Most vehicle models with a V6 engine have a single spark plug per cylinder, making it a total of 6. Jeep, Honda, Ford, Nissan, Chevy, and Toyota are examples of this.

You can physically count the number of spark plugs in the engine bay. Also, you can count the spark wires on the sides of the engine cover.

Having six wires means that there are six spark plugs. And if there are 12 wires, there are 12 spark plugs as well.

South Korea, the United States, Mexico, and Japan’s vehicle manufacturers usually have one spark plug per cylinder of the V6 engine. Only manufacturers in Europe tried using 2 spark plugs per cylinder.

V8 engine

While it’s a common assumption that every V8 engine has 8 spark plugs, the number usually depends on the V8 motor type in use.

Figure out the motor type if it’s a V8 engine for an accurate answer. The regular V8 engine motors have eight spark plugs in total, one per cylinder.  

However, some European and American manufacturers use dual-ignition or twin-spark technology. In that case, V8 motors have spark plugs that exceed the number 8.

V8 motors with dual ignition technology have two spark plugs per cylinder to maximize horsepower while reducing emissions.

The HEMI V8 motor has ignition coils and not wires. Every ignition coil power has two spark plugs per cylinder, making a total of 16 spark plugs.

V10 engine

V10 engine designs are great for large and heavy cargo vans and Ford trucks like the Ford E-series. Its engine has 10 piston cylinders positioned in a V pattern surrounding the same crankshaft.

In addition, V10 engines are a combination of 2 five-cylinder engines. So, they contain a total of 10 spark plugs. Aside from the enhanced performance, these engines are widely known for the remarkable sound they produce.

To understand the V10 engine’s capabilities, consider a V6 engine fitted with 4 additional cylinders or a V8 engine with two additional cylinders.

You will find V10 engines in powerful cars like the Lexus LFA and Dodge Viper. Also, it’s available in Ford E250 to E450.

V12 engine

V12 engines tend to be heavy and great in size because they are very powerful. They consist of 12 cylinders that form a V shape around a single crankshaft.

Regular engines of this type have a single spark plug for every cylinder, with 12 spark plugs in total. However, other manufacturers like Mercedes use 2 spark plugs per cylinder, making a total of 24.

These twin spark plugs provide a more thorough fuel-air mixture ignition in the combustion chamber. So, having 2 spark plugs igniting simultaneously can provide two flames providing total combustion.

This process is also faster than the ones with one spark plug.  Also, the double ignition is great for optimizing the power generated while keeping emission levels at a minimum.

A V8 engine can fire 4 times, while a V12 engine can fire 6 times. This means that the engines run more smoothly and work faster.

Types of Spark Plugs

Four main spark plug types have been developed over the past years. The older types of spark plugs have been surpassed, but their use in small low-power engines and classic cars is still valuable.

Copper Spark Plugs

Copper spark plugs are composed of a copper core with a nickel alloy coating where sparks are generated.

Their drawbacks are their low melting point because of the nickel and alloy components, which means they cannot support high-power engines that long, the need for the highest voltage, and the shortest lifespan.

However, these plugs still have various uses on older cars without direct fuel injection, not affecting fuel economy.

Lastly, copper spark plugs are the least expensive. So, upgrades are not needed if your engine is using them.

Platinum Spark Plugs

A platinum spark plug replaces the copper alloy tip with platinum. This can significantly increase its lifespan.

Also, they can generate more heat which helps in reducing carbon buildup. It’s another factor that gives its longevity.

This plug type is best for new cars with a coil-on-plug ignition system.

Double Platinum Spark Plugs

The platinum coating is found in double-platinum type spark plugs at the ground and center electrodes. This makes them last longer and more efficiently.

It is ideal for wasted spark ignition systems that usually generate more wear on electrodes.

Also, in this system, each ignition coil can ignite two plugs at a time. One in the exhaust stroke’s cylinder and the other in the compressor stroke’s cylinder.

Lastly, the spark becomes wasted because the air or fuel mixture already burnt out in the past stroke.

Iridium Spark Plugs

This spark plug type lasts longer because iridium is a more durable and harder material than platinum. Its center electrode is small, requiring less voltage to generate a spark, making it more expensive.

At present, most vehicles use the iridium spark plug to minimize the possibilities of car breakdowns.

Silver Spark Plugs

A silver spark plug is not durable enough and is not meant to be used on old-performance cars. Also, it does not last as long as platinum or iridium spark plugs.

Its lifespan is the same as or better than copper spark plugs, but platinum alternatives now replace this plug.

Parts of a Spark Plugs

This section teaches the components making up a spark plug and their functions. Their design has not changed much since the combustion engine’s inception in the late 1800s.

Insulator

Insulators insulate the center shaft, terminal, and center electrode from their housing. It helps prevent the high voltage’s escape from the electrodes.

Gasket

Gaskets make the engine and housing perfectly fit each other and maintain the combustion chamber’s airtightness.

Terminal

Terminals are attached to a high-tension cord, allowing high-voltage currents to flow to the ignition system. Also, it contains a terminal nut to support all high-tension cords. It can be removed if the vehicle does not use a terminal nut.

Center Shaft or Stem

Center shafts connect to the center electrode and terminal. It is steel and allows high-voltage current to flow from the terminal to the center electrode without losses.

Ring, Parking Washer

This component helps the housing and insulator to fit tightly to each other and keeps them air-tight.

Electrode with Copper

This special nickel alloy is placed at the center electrode for reducing electrode wear. Also, copper is sealed into its center section for enhanced thermal conductivity.

Glass Seal

Glass seals are located between the insulator and center shaft to maintain air tightness. It is made of a mixture of copper and glass powder.

They are charged in the center electrode and center shaft’s installation section and then melted at high temperatures. Also, they prevent gaps even under harsh conditions.

Housing

This component creates an outer shell to support and surround the insulation. It allows the engine installation of a spark plug.

The ground electrode at its bottom part makes the current flow from the engine to the center electrode over a gap.

Center Electrode

Center electrodes are laser-welded to an iridium alloy tip. It is usually 0.4 millimeters in diameter to produce the center electrode.

The purpose of center electrodes is to secure a reliable spark, improve the ignition, lower the spark voltage, and reduce the quenching effect.

U-groove Ground Electrode

U-groove ground electrodes are important because they allow large ignition energy and easily widen the flame core size.

Tapered Cut Ground Electrode

The electrode’s tip is cut to a tapered shape. It reduces the quenching effect that can help enrich the ignition performance.

How Spark Plugs Work

This video starts with a 3D model of a spark plug and its functions. It is followed by explanations of every component and its significance in the spark plug.

The next part is about the applications and how electrical noise can disrupt other electrical circuits. And then, he dives into how spark plugs work by letting the current flow in high voltage until it flows into the center electrode and the resistor.

Next is, he explains that reach needs to be the same if you replace the old spark plugs. Having too long a reach can cause the piston crown to collide with the spark plug. Lastly, he discusses the hot and cold spark plugs and their differences.

Spark Plug States You Should Be Aware Of

These are the ten states your spark plug can be in. Generally, it’s best to have your vehicle inspected to prevent further problems if you suspect an issue. Keep reading so you won’t miss any.

Normal state

Normal plugs usually have a bronze to grayish color while using an electrode that has been worn a bit. It will have proper operating conditions and heat range when the motor is in good condition.

Carbon deposits

These are sooty, black, and dry deposits on your plug. Carbon deposits are conductive and create a path for spark plugs to misfire.

Ash deposits

Ash deposits are light brown remains gathered on the sides, the center of electrodes, or both.

These remains are created from oil additives. Also, extreme amounts may cause a spark that will trigger misfiring.

Overheated

This is when the electrode becomes worn out, and the remains disappear. The result will be a reduced plug life.

Having your plugs checked for proper heat and being careful with over-advanced ignition timing are how to detect and prevent it, respectively.

Oil deposits

This condition involves an oil coating covering the spark plug and preventing the spark from arcing across the gaps.

Also, it can lead to delays, misfiring, and tough starting. Having necessary repairs and putting in innovative plugs can fix this.

Detonation

Here, the insulators might have cracked or chipped. It is caused by improper gap setting that may lead to piston damage that has not been resolved early.

Worn

In this condition, electrodes are rounded and may have tiny deposits on the firing end. You will have a hard time creating a spark to start the engine.

High-speed glazing

This means that the combustion chamber temperature has suddenly risen during hard acceleration. The normal deposits melted to form a conductive coating, causing misfiring at high speed.

Pre Ignition

This phenomenon occurs when the air-fuel charge ignites, and the piston compresses the charge. The source can be caused by lead or carbon deposits, a cracked spark plug tip, or a burnt exhaust valve.

Oil fouled

Oil fouling happens when oil enters the combustion chamber. The oil deposits will cover the spark plug, keep the spark from arcing across the gaps, and take a shorter way to ground the oil.

This is a common early sign of engine wear.

Frequently Asked Questions (FAQs):

Can You Change Your Own Spark Plugs?

Yes, you can replace your spark plugs yourself, although there might be some caveats. You must use factory-approved or OEM parts to avoid compromising your engine quality.

Make sure to replace spark plugs correctly with enough research and knowledge of the special tools needed. Follow the manufacturer’s instructions as overtightening the newly installed spark plugs can damage cylinder heads.

How to know your spark plugs are failing?

When your spark plugs are starting to fail, you will experience problems with your engine. The initial symptoms are jittery and rough idle, followed by difficulty starting your engine.

Another common problem is surging. When the engine’s revolutions per minute become higher than normal, it makes up for the faulty spark plug. Other symptoms are poor acceleration, increased fuel consumption, and engine misfiring.

Can I replace only one spark plug?

Replacing only one spark plug will mess with the rotation of the plug’s lifetime. Although it may be fine for quick fixes, they should all be changed simultaneously to attain the engine’s best performance.

Are all spark plugs the same size?

Spark plugs do not all have the same sizes. They have different gaps and are manufactured using various metals. The common spark plug sockets used with a normal socket wrench are popular in different cars.

However, you cannot be sure that your car uses these. You should find out your socket type and then check the size.

When Should Spark Plugs Be Changed?

The general rule of thumb for changing spark plugs is every 30,000 miles. However, keep in mind that there is a possibility that they may fail sooner or later than that.

The Takeaway

To answer, “how many spark plugs do I need?” is that it often matches the number of cylinders a vehicle contains. So, open the hood and count how many cylinders you’ve got.

When replacing your spark plugs, remember to replace the whole set instead of the single failed one to keep your engine at peak performance.