Most V8 engines have eight spark plugs — one for each cylinder.
However, some V8s use dual ignition systems, meaning they have 16 spark plugs instead.
The exact number depends on your engine design, not just the number of cylinders. Certain performance and modern gasoline V8s use two spark plugs per cylinder to improve combustion and emissions.
In this guide, we’ll explain how many spark plugs a V8 engine has, how to tell if your engine uses a twin spark setup, and answer common questions about spark plug types, lifespan, and replacement.
This Article Contains:
- How Many Spark Plugs Are in a V8 Engine?
- How to Tell if Your V8 Comes with a Twin Spark Engine?
- 5 FAQs About Spark Plugs
How Many Spark Plugs Are in a V8 Engine?
Whether you have a Dodge Charger, a Chrysler, a Mercedes AMG, or an Alfa Romeo, the total number of spark plugs in your car’s engine depends on two things: The type of engine and the number of cylinders you have.
Most V8s have eight spark plugs — one per engine cylinder.
However, twin-spark engines without a distributor and newer HEMI engines with MDS (Multiple-Displacement Systems) have two spark plugs per engine cylinder — so sixteen in total.
Let’s find out why that’s the case.
Why Do Some V8 Engines Use 16 Spark Plugs Instead of 8?
Some V8 engines use two spark plugs per cylinder (16 total) to improve combustion efficiency, reduce emissions, and enhance engine smoothness.
Larger V8 combustion chambers take longer to burn the air-fuel mixture. Using two spark plugs allows the flame to spread more evenly and quickly, resulting in a more complete burn. This design helps certain engines meet emissions standards and perform more consistently, especially under load.
However, modern single-spark V8 engines achieve similar efficiency through advanced fuel injection and ignition timing — making dual spark systems less common today.
Interestingly, this is only true for a gasoline engine. A diesel car’s engine utilizes a glow plug instead. A glow plug doesn’t ignite the air-fuel mixture in the diesel engine combustion chamber. Rather, superheated compressed air in each cylinder fires the fuel.
Therefore, you need to know what type of engine you have.
How to Tell if Your V8 Comes with a Twin Spark Engine?
The easiest way to check if you have dual ignition technology in your gasoline engine is to look inside your owner’s manual.
Alternatively, you can visually inspect your car’s engine. Here’s how:
- Pop your hood and remove your engine cover. Just make sure your car has been off for a while, so your engine isn’t hot.
- Count each spark plug wire located alongside each cylinder head (generally blue, red, or black wires). There’s one spark plug wire per spark plug.
- Now, if you don’t see any spark plug wires, your V8 engine uses coil packs instead. These are located on top of your V8 engine, away from the crankshaft, and there’s one coil pack per spark plug.
- So, if you count more than eight wires or coil packs, you have a twin spark engine with sixteen spark plugs in your V8 motor.
NOTE: Earlier generations of the HEMI V8 engine utilized the ignition coil, distributor, and spark plug cables with one spark plug per cylinder. The modern 5.7 HEMI engine with 2 spark plugs per cylinder was introduced in 2003.
With that said, let’s check out how many spark plugs some common V8s have:
| Car Make | Number Of Spark Plugs In V8 |
|---|---|
| 2015 Ford Mustang GT | 8 |
| 2003 5.7L HEMI Chrysler | 16 |
| 2003 Mercedes CL55 AMG | 16 |
| 2006 Dodge Charger R/T | 16 |
| 2008 Chevrolet Corvette | 8 |
| 2016 Ford F150 | 8 |
| 2013 5.7L Dodge Ram | 16 |
If you’re still unsure how many spark plugs your V8 engine has, ask your automotive dealership or a professional mechanic for help.
Now, let’s look at some FAQs on spark plugs.
5 FAQs About Spark Plugs
Here are five FAQs about spark plugs and their answers:
1. What Are the Signs of a Faulty Spark Plug?
Here are some common problems associated with a bad spark plug:
- Trouble starting the car
- Illuminated check engine light
- Engine shakes caused by misfires
- Increased emissions
- Reduced fuel economy
- Widened spark plug gap
If your plugs, the spark plug gap, or any electrical connector linking them to the ignition system is faulty, these tiny electrodes won’t do their job, and you’ll need a spark plug replacement.
A bad spark plug won’t ignite the air-fuel mixture in your cylinder’s combustion chamber — causing misfires and making driving a challenge.
2. What Kinds of Spark Plugs Are There?
You’ll typically find spark plugs made from these four different materials:
- Silver spark plugs: Silver plugs are rare these days. They work well in older car models but aren’t the best spark plugs.
- Copper spark plugs: They’re mid-range plugs with a low melting point.
- Platinum spark plugs: Platinum spark plugs reduce carbon build-up and have greater longevity than copper plugs, but lower than iridium plugs.
- Iridium spark plugs: Iridium plugs are the best spark plugs you can buy. They have the highest melting point and a longer lifespan than platinum plugs.
NOTE: When buying a new spark plug for your gasoline engine, it’s recommended that you get an Original Equipment Manufacturer (OEM) plug. Cheap aftermarket plugs can cost more than OEM spark plugs in the long run, as OEM spark plugs tend to have better fuel economy.
3. How Often Do You Need to Change Your Spark Plugs?
How long your spark plugs last depends on what type of spark plugs you have.
- Silver spark plugs: Silver plugs can last up to 20,000 miles.
- Copper spark plugs: Copper plugs need to be replaced every 30,000 to 50,000 miles.
- Platinum plugs or iridium spark plugs: Platinum plugs or iridium plugs will last 50,000 to 120,000 miles.
Check your owner’s manual if you’re unsure which plugs your V8 motor has.
4. What Are the Benefits and Drawbacks of More Spark Plugs?
There’s no correct answer when it comes to wanting a dual ignition system or not. What matters is the engine design.
Generally, more plugs result in a cleaner burn — meaning increased fuel efficiency.
However, modern single spark engines have a better fuel economy, fewer emissions, greater torque, and more horsepower than when Alfa Romeo invented dual ignition technology in 1914.
So, the benefits of having more of these electrodes in a V8 or V6 engine have diminished in recent years. Unfortunately, the increased cost of fixing a more complicated V8 or V6 engine hasn’t.
5. How Do You Replace Spark Plugs?
Changing spark plugs yourself can be a DIY project.
However, it’s always better to let your mechanic do it for you, especially if you don’t have any spark plug removal experience. Spark plugs can be notoriously difficult to detach after many miles in the engine, and a mistake could cost you a new cylinder head.
Here’s a general guideline for spark plug removal:
- Pop your hood and remove your engine cover.
- Locate your spark plugs by checking for the spark plug cables or ignition coil packs.
- Remove the spark plug cables or coil packs from each spark plug.
- Use a spark plug socket or a torque wrench to unscrew your spark plug from the cylinder head.
- Attach a new spark plug to the magnetic tip of the spark plug socket and drop it into the hole.
- Tighten your new plug to the correct torque specifications using a torque wrench.
- Do this for each existing, old spark plug.
- Apply dielectric grease to the boots of your spark plug cables to act as an insulator. (Don’t add too much dielectric grease).
- Reconnect each plug wire or coil pack to each new plug.
- Finally, try turning on your car.
Ready for a Spark Plug Replacement?
Depending on your V8 engine, you either have eight or sixteen spark plugs. Consult your car owner’s manual or physically count the number of spark plug cables or coil packs your V8 motor has.
Once it’s time for a spark plug replacement, it can be a DIY project. However, you should always err on the side of caution and avoid changing spark plugs yourself to prevent damage to your car.
So how do you do that?
Well, you could always reach out to AutoNation Mobile Service and let our expert technicians replace them for you.
AutoNation Mobile Service is a mobile maintenance and auto repair solution with competitive and upfront pricing, available 24/7. And you can easily book us online.
Contact us now, and our mechanics will drop by your driveway and do a spark plug replacement in no time!