Sparks of Power: Your Challenger’s Ignition System

The ignition system is responsible for sending spark to the combustion chamber during the combustion stroke. On modern Challengers, the computer sends a signal to the coil pack which sends power to the spark plug in order to ignite the compressed fuel and air mixtures in the engine.

Without the spark, the engine could not run. Modifying the ignition system is a great way to ensure that all the fuel in the chamber is burned. This will result in increased power, a smoother running engine and even increased fuel economy.

The spark plugs are actually what ignite the fuel in the combustion chamber. These plugs are diodes that actually use an electrical arc to ignite the fuel. By selecting the right plugs for your engine, you will ensure the best possible burn to optimize engine performance.

Heat Range: The heat range of a spark plug doesn’t actually measure how hot the plug’s spark is. This refers to the temperature the tip of the plug will reach.

Cooler plugs will dissipate heat better than a hotter spark plug. Understanding the proper heat range is crucial to proper performance. If the tip of the plug is too cool, it may not ignite all of the fuel in the chamber. If it is too hot, it can cause pre-detonation. 

Indexing: Indexing a spark plug is a great way to unlock one or two horsepower with your engine. Ideally, you want the opening of the ground strap on the plug pointed toward the intake valve; doing this can be a bit of a trick on the hemi as the plugs aren’t visible when they are installed in the valve cover.

One can mark the side of the plug with the ground strap and use specialized washers to ensure the plug sits in the right position once it’s installed. It’s important to remember to make sure each plug is gaped to the manufacturer’s specifications before attempting this.

Spark plugs perform well based on the material used for the core. The core of the plug is the conductor and this is how the spark is sent from the coil to the cylinder. The level of conductivity dictates how hot the spark burns and how well the fuel mixture is burned.

Copper: Copper is known to be the best conductor of electricity used in spark plugs. However, it does have a few drawbacks. The biggest is its low melting point. This makes longevity an issue. As a cool burning plug copper is often the choice for performance driving. These are also the cheapest plugs on the market.

Iridium: Iridium plugs are the most expensive spark plugs on the market. This is due to the fact that Iridium is the most durable material used in spark plugs as the core. This material will outlast platinum and copper and can perform well in both performance and street applications.

Platinum: Platinum is a much more durable material than copper as it is harder and has a higher melting point. These plugs run hot and this keeps them from fouling when used with rich mixtures. The real advantage of platinum plugs is their balance between a low price point and a long healthy life.

Hemispherical combustion chambers are much larger than common cylinder heads used on engines with similar displacement. This means that more air and fuel will need to be burned during the combustion cycle. Two spark plugs per cylinder are used as it is the best way to ensure all of the air and fuel is burned.

To pick the right plugs out, you will need to consider how you’re Hemi is set up. The Hemi uses two spark plugs, so in theory one won’t typically have to run very hot plugs. 

The reason two plugs are used is because the cylinder head allows it. The chamber is also much larger so multiple sparks will ensure that all of the fuel and air is ignited.

On the third-generation Challenger, you’re going to find a direct ignition system. No distributor is present. The timing is controlled by the ECM and coil packs that sit directly on top of the valve covers. The ignition coils job is to pick up the signal sent out by the ECM and release its stored energy to fire the spark plug as the ECM dictates it.

Aftermarket Coils: An aftermarket coil works much the same as the factory coils will but it will work to magnify the spark even more. Bringing up the voltage that is sent to the plug will actually make for a hotter spark. If you’re in the need of a hotter discharge, upgrading the coil is where to focus your energy rather than the plugs.

A voltage booster works just the same as a coil; it picks up a small electrical current and magnifies it. The voltage booster works to magnify the voltage that is sent to the coil. The more power that is sent into the coil, the more it can discharge. This is a great way to further increase spark temperature, but should only be pursued when you are switching from the stock coils to aftermarket ones.

Upgrading your ignition system is about taking advantage of a good situation. In stock form, an engine with the factory ignition system may have some issues burning what fuel and air is already present. If you upgrade the ignition at this point you will see a difference in power output and engine performance.

When you start throwing power adders onto an engine more air and fuel may go unburned with a weak ignition system. By Upgrading the ignition system, you are working to ensure all the fuel is burned and you’re taking that combustion chamber for everything it’s got. For maximum performance, the ignition system must always be addressed.