How Many Spark Plugs in a V8 Engine? (+ 7 Things to Know)

Do you want to know how many spark plugs are in a V8 engine?

Most V8 engines have eight plugs. However, this is not a general rule as some v8 engines have 16 spark plugs. The number of spark plugs in a V8 engine depends on the design of the engine.

This article will give you extensive knowledge on how many spark plugs are in a V8 engine and help you find out if you have a twin spark engine (which is an engine with double the number of spark plugs)

This article also explains how to identify faulty spark plugs, the steps involved in changing a spark plug, and other related questions will also be answered as we proceed.

The type of engine determines spark plugs in a car engine and the number of cylinders in the engine, regardless of the brand or model of the car, be it an Alfa Romeo, a Mercedes AMG, a Chrysler, or a Dodge Charger.

Many V8 engines have 8 spark plugs, with one attached to each cylinder. However, two spark plugs could be connected to an engine cylinder, making sixteen plugs for a twin spark engine without a distributor and recent HEMI engines with MDS (Multiple-Displacement Systems).

The intriguing part is that this only applies to gasoline engines. Diesel car engines use glow plugs in place of a spark plug.

Glow plugs do not ignite air-fuel mixtures in the engine’s combustion chamber. Instead, each cylinder holds hot compressed air, which burns the fuel.

Hence, it is necessary to know the engine type in a car.

Also Read: How Many Spark Plugs Does a Diesel Have?

How to Know if Your V8 Is a Twin Spark Engine?

How Many Spark Plugs in a V8 Engine

A straightforward way a gasoline engine can be checked when on the lookout for a dual ignition system is by reading the owner’s manual.

Another method of checking for dual ignition technology in gasoline engines is to look at the car engine physically. Here are steps to carry out the inspection:

  • Lift the engine cover after it has popped and is no longer attached firmly. Be sure to have turned off the car for some minutes, so the engine will not be too hot.
  • Count every spark plug connection and cylinder head you see (The wires are usually red, blue, or black.) A spark plug cable has a spark plug attached to it.
  • If no spark plug connections are found, the engine utilizes coil packs. Coil packs are found far-off the crankshaft, at the topmost part of the engine, and are usually found in a spark with a spark plug.
  • If over eight plug cables or more than eight coil packs are seen, the V8 engine comprises sixteen plugs, and the car is equipped with a twin spark engine.

Note: An old engine like HEMI V8 works with ignition coils, distributor, and spark plug cables with a spark plug attached to a cylinder.

Recent engines like the 5.7 HEMI introduced in 2003 has two spark plugs attached to each cylinder.

Are There Any Benefits To Having More Spark Plugs In A V8 Engine?

There’s no definite conclusion to this. Every manufacturer designs their engines distinct from others, and although some engines have identical designs, their internal composition may differ.

The more important question is why engines have extra spark plugs and not the advantages of having different spark plugs.

All these relate to the engine design. Two spark plugs are required to complete burn at both low and high engine speeds for the HEMI V8 having an MDS (Multiple-Displacement System) and VCT (Variable Camshaft Timing).

Having VCT (introduced in 2009) in HEMI engines helps increase or reduce timing regarding camshaft. Usually, valve timing reduces when the engine speed is high to increase the horsepower’s efficiency.

Conversely, valve timing increases when the engine speed is low to give more force.

For this reason, some Dodge vehicles having recent HEMI V8 engines had their axle ratio reduced to 2.65 from 2.87.

Dodge did this without tampering with the resilient acceleration HEMI V8 engine is known for. This also led to better fuel management in regular driving applications.

This does not necessarily mean that V8 engines with single-spark units are inferior to twin-spark or dual-ignition.

However, Engine design and structure determine superiority. Other car producers prefer to go through the less complicated route to reduce expenses.

The disadvantage of having extra spark plugs exposes itself here. Firstly, more time is used in repairing twin-spark engines, which means extra hours will be spent on labor, resulting in additional expense for the car owner.

The price of changing 16 spark plugs should also be considered. The truth is, replacing spark plugs is not as expensive as changing sensors.

If looked at critically, twin-spark or dual ignition used by V8 engines needs to spark plugs twice the amount required for a single spark engine; hence, more money will be paid for the replacement.

If the iridium spark plugs go for $30 each or thereabout, $480 will be set aside for sixteen plugs. But for the regular V8 engine, it only takes about $240, excluding labor and other allied fees, to change a complete set.

Also Read: Spark Plug Replacement Cost – Best Price Estimate

Should I Replace All Spark Plugs at Once?

How Many Spark Plugs in a V8 Engine

Yes, you should replace all the spark plugs at the same time when changing spark plugs in your v8 engine. Partial spark plug replacement by some people is done to reduce cost.

If spark plugs are identical, then there is nothing bad with partial replacement, provided that the remaining plugs are in good condition and of the identical type.

Although it’s practically good not to change all spark plugs once, it is best to replace them once. But, again, going through the car’s manual may convince you when unsure of what to do.

Some known engines like the Mitsubishi V6 have two groups of spark plugs; ordinary and long-life.

Three ordinary plugs and three long-life plugs are found in the engine. The second set of cylinders is tough to access, so there is a need for long-life plugs to avoid replacing them too often.

The other set contains the three ordinary spark plugs and needs regular replacements at definite intervals.

However, all spark plugs within a V8 engine should be replaced once. Regarding V8 engines like the HEMI 5.7-liter, the factory-made engine has ordinary plugs; Chrysler also advises replacing all plugs after 30,000 miles!

What Are the Symptoms of a Bad Spark Plug?

Symptoms of a Bad Spark Plug

Some known issues related to a defective spark plug include:

  1. Difficulty starting the car
  2. A lit check engine light
  3. Engine jerking triggered by misfires
  4. Higher emissions
  5. low fuel economy
  6. Broadened spark plug gap

When a spark plug, the plug gap, or any electrical connector connecting the spark plugs to the ignition system is damaged, the plugs will not function, and spark plug replacement will be necessary.

Air-fuel combination in the cylinder’s combustion chamber will not ignite if a spark plug is damaged, resulting in misfires, making driving more difficult.

Also Read: Oil on Spark Plug Threads (Causes & Solutions)

What Are the Types of Spark Plugs

Spark plugs are usually made from four different elements. They are:

  1. Silver-spark plugs are uncommon in recent times; they work remarkably for older car engines but are not the best plugs.
  2. Copper spark plugs: They are average plugs with a sharp melting point.
  3. Platinum spark plugs: platinum spark plugs last longer than copper spark plugs. They are efficient in decreasing carbon formation, but they do not last as long as the iridium plug.
  4. Iridium spark plugs: The finest plugs available are Iridium spark plugs. Their melting point is concentrated and usually lasts longer than the platinum plug.

Note: When getting a new spark plug for a gasoline engine, it’s better to get an Original Equipment Manufacturer (OEM) plug.

Aftermarket plugs become more expensive than OEM s plugs over time because OEM plugs use fuel better than aftermarket plugs.

How Often Should You Change Spark Plugs?

How Many Spark Plugs in a V8 Engine

The various types of spark plugs usually determine the life span of a spark plug. Here are the number of miles various spark plugs should be replaced

  • Silver spark plugs: Silver plugs should be changed After 20,000 miles,
  • Copper spark plugs: Copper spark plugs need to be replaced every 30,000 to 50,000 miles.
  • Platinum plugs or iridium spark plugs: Platinum plugs or iridium plugs should be replaced between 50,000 and 120,000 miles.

The owner’s manual can clarify which type of spark plug is in your V8 engine in case of uncertainty.

How to Replace Spark Plugs

The car owner can change spark plugs easily. However, it’s usually recommended that a mechanic change it, particularly when the car owner has no experience removing plugs.

This is because removing Spark plugs after a while in car engines can be seriously difficult and, if done incorrectly, could damage the cylinder head.

Spark plug replacement can be done following this general procedure:

  1. Pop the bonnet and lift the engine cover.
  2. Look around and find ignition coil packs and spark plug wires or find spark plugs.
  3. Spark Plug wires or coil packs should be detached from every spark plug.
  4. A spark plug socket or a torque wrench can be used to loosen the spark plug from the cylinder head.
  5. A new spark plug should be coupled to the metal edge of the plug socket and dropped into the cylinder head.
  6. Screw in the new plug, bearing in mind the exact torque specifications with a torque wrench.
  7. Apply this for every spark plug that is being replaced.
  8. Use dielectric lubricant on the boots of the plug wires to work as insulators. (Avoid using excess dielectric grease).
  9. All plug wires should be re-connected to every new plug or coil pack as the case may be.
  10. Then, try starting the car.

Check out this video for more tips on how to replace spark plugs

Things to Remember Before You Replace the Spark Plugs in a V8 Engine

Spark plugs are replaced in any car by merely removing the plug cable or ignition coil, detaching and fixing new ones in place of the old spark plugs removed. Although the HEMI 5.7-liter V8 engine requires a different process.

  1. Allowing the heat from the engine to diminish completely is an important step that should not be forgotten. This applies to all engines having aluminum heads. Aluminum being more brittle than steel requires serious care to be observed when replacing spark plugs. It is critical to allow a V8 engine with an aluminum head to cool off (advisably overnight) before taking out the plugs.
  2. Every spark plug has a gap that ought to be confirmed before replacement. For a V8 engine like the HEMI, 0.043-inches is the adequate gap for an ordinary plug. Cars are built differently; hence, the owner’s manual can be used to decide the adequate gap required for the spark plugs.
  3. Using the correct amount of force when screwing spark plugs is essential. The aluminum head can be easily destroyed if spark plugs are screwed too tight. You can check your car’s manual for the required amount of torque. 13 lbs.- ft is the torque specification for screwing spark plugs for HEMI V8 engines.

Frequently Asked Questions – How Many Spark Plugs in a V8 Engine

Does a V8 Have 16 Spark Plugs?

There are two plugs attached to each cylinder in the HEMI V8 engine. Hence, when changing spark plugs, remember that not eight but sixteen plugs will be replaced. In addition, remember that all engines like the HEMI V8 are built on coil-on-plug ignition structures.

How Many Spark Plugs Does a 5.7 Hemi V8 Have?

A 5.7 HEMI V8 has 16 spark plugs. A HEMI V8 engine has 2 spark plugs per cylinder, making the total number of spark plugs 16.

How Much Are Spark Plugs for a V8?

For a V8 engine, spark plugs are priced at around $16 to $100 per set; however, this is subject to the number of cylinders the engine has and the kind of plug. When considering the cost, it should be remembered that specific specialty engines have two plugs attached to a cylinder.

How Many Spark Plugs Do You Need?

The number of plugs required can be determined by the engine’s totality of cylinders—a plug to a cylinder. For instance, four plugs are attached to 4-cylinder engines. Many spark plugs are manufactured from various kinds of metal to fit the engine, with some not as expensive as the rest.

How Many Plugs Does V8 Have?

A V8 engine has 8 spark plugs. There is one spark plug attached to each cylinder. Hence, in an Ordinary V8 engine, eight plugs can be found.

How Many Spark Plugs Does a V8 Tundra Have?

A V8 Tundra engine has 8 spark plugs. Every cylinder in the Tundra has its own spark plug. Hence, in a V8 Tundra, eight plugs can be found.

How Many Spark Plugs Does a Diesel V8 Have?

Although spark plugs can’t be found in diesel vehicles, the method is comparable. All V8 machines, including V8 diesel, have eight cylinders. Hence, the engine of a V8 diesel has eight glow plugs.

How Many Spark Plugs Does a V8 Chrysler 300 Have?

A 5.7L HEMI engine is found in the 300C, which has 16 spark plugs. Each cylinder has two spark plugs attached to them. If the owner of a Chrysler 300C decides to change the plugs himself, it is advisable to set aside a good time for doing so.

Conclusion – How Many Spark Plugs in a V8 Engine

There are either eight or 16 plugs in a V8 engine. Go through the car’s manual or ascertain the spark plug wires or coil packs the engine has physically.

When spark plugs are due for a change, the car owner may choose to do it personally. However, caution ought to be taken.

So, car owners are usually advised not to change the spark plugs in their engine to avoid damaging the car.

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

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