As a vehicle owner, you strive to extract every last ounce of power from your engines. I mean, it’s what we all do. And this brings us to the key components of the ignition system, coil packs and distributors.
Now, the question is, coil pack vs distributor – which design unlocks the true potential? Well, coil packs are superior to traditional distributors in key areas like timing precision, spark energy, reliability, and modern engine integration. Overall, coil packs outshine distributors in nearly every major category.
Want to know how and why this is true? Then, sit back and enjoy the ride through this in-depth comparison till the end.
Coil Pack vs Distributor: Quick Comparison Table
First off, let’s get to know some of the major differences between coil pack vs distributor at a glance:
|Number of spark plugs||One coil per spark plug||One coil pack for all spark plugs|
|Ignition timing||Controlled by the car’s computer||Controlled by the distributor|
|Durability||More durable||Less durable|
|Ease of replacement||Easier to replace||More difficult to replace|
|Cost||More expensive||Less expensive|
Coil Pack vs Distributor: How They Work
To give you a bit of a background, the ignition process in gasoline engines involves four steps:
1) Generate a high-voltage current from the battery
2) Distribute the current to the correct spark plug at the right time
3) Create a spark across the spark plug gap
4) Ignite the air-fuel mixture in the cylinder. (According to a handbook on gasoline engines by Robert Bosch).
Coil packs and distributors differ in performing the second and third steps. The primary operating principles of each system differs in the following way:
- Coil packs
A coil pack consists of individual coils that are mounted directly on or near the spark plugs. Each coil has two terminals: one connected to the battery and one connected to the ECU.
The ECU sends a signal to each coil when it needs to fire, causing it to generate a high-voltage current. The voltage-current flows through the spark plug wire to the spark plug.
A distributor consists of a rotor, contact points, and a distributor cap. The rotor is attached to the camshaft and rotates inside the distributor cap. The contact points are a set of electrical contacts that open and close as the rotor spins.
The distributor cap has metal terminals that connect to the spark plug wires. As the rotor turns, it makes contact with each terminal in sequence, sending the current to the corresponding spark plug.
Timing Control Comparison
As articulated in a 2000 peer-reviewed study, the timing of the ignition system refers to when the spark is delivered to each cylinder. If comparing the timing control of Coil pack vs distributor, coil packs and distributors have different methods of controlling the timing.
- Coil packs
Coil packs are controlled electronically by the ECU. ECU uses sensors to monitor various engine parameters such as speed, load, temperature, and knock. The ECU then calculates the optimal timing for each cylinder and sends signals to each coil accordingly.
They use mechanical advance mechanisms that adjust the timing based on centrifugal force and vacuum pressure. Centrifugal force causes weights inside the distributor to move outward as the engine speed increases, advancing the timing.
Vacuum pressure causes a diaphragm inside the distributor to move inward or outward as the engine load changes, advancing or retarding the timing.
Spark Energy Comparison
The spark energy of an ignition system refers to how much voltage and current are delivered to each spark plug.
- Coil packs
They produce higher voltage and current output because they have individual coils that fire only once per engine cycle. This means that each coil has more time to recharge between sparks.
Coil packs tend to have higher combustion efficiency and lower emissions. It’s because they produce stronger sparks that can ignite the air-fuel mixture more completely. This results in complete combustion, less unburned fuel, less carbon deposits, and lower exhaust gas temperatures.
They are limited by having a single coil that has to fire multiple times per engine cycle. This means that the coil has less time to recharge between sparks, resulting in lower voltage and current output.
Distributors tend to have lower combustion efficiency and higher emissions. It’s because they produce weaker sparks that may not ignite the air-fuel mixture completely.
Maintenance and Serviceability Comparison
From an expert point of view, the maintenance/serviceability of an ignition system refers to how often and how easily it needs to be inspected, adjusted, repaired, or replaced.
- Coil packs
They require less frequent maintenance because they are largely sealed units with no moving parts. The only parts that need to be replaced are the coils when they fail, usually indicated by a check engine light or a misfire code.
Coil packs have lower ongoing costs for maintenance and service. The parts need to be replaced less often while the labor is also less intensive.
They have moving parts that are subject to wear and tear over time. The contact points need to be cleaned and adjusted regularly to prevent arcing and corrosion.
Additionally, the rotor and distributor cap need to be inspected and replaced periodically to prevent damage and misfires. The spark plug wires need to be checked and replaced as well to prevent deterioration and leakage.
Distributors have lower initial costs but higher ongoing costs for maintenance and service. The parts are cheaper. However, they need to be replaced more often. The labor is also more intensive and time-consuming.
- Coil packs
Coil packs are more reliable because, again, they have no moving parts that can wear out or break down. Coil packs typically last between 100,000 and 150,000 miles before they need to be replaced.
They are less reliable because they have moving parts that are more prone to wear and tear over time.
They are also more sensitive to environmental factors such as moisture, dust, heat, and vibration. These factors cause corrosion, damage, or misalignment of the components.
Distributors typically last between 50,000 and 100,000 miles before they need to be replaced or rebuilt.
Customization Potential Comparison
- Coil packs
Coil packs have less customization potential because they are controlled electronically by the ECU. This limits the amount of adjustment that can be done without reprogramming the ECU or installing a piggyback device.
Coil packs can also be upgraded with aftermarket parts such as high-performance coils, wires, etc. However, the effect may not be as noticeable as with distributors.
They have more customization potential because they can be adjusted manually for different timing curves. This allows for fine-tuning the ignition system to match the engine characteristics, fuel type, altitude, etc.
Distributors can also be upgraded with aftermarket parts such as high-performance coils, caps, rotors, wires, etc.
Modern Usage Comparison
Coil packs and distributors have different user bases at this point in time.
- Coil packs
Coil packs are now used in the vast majority of new vehicles because they offer higher efficiency and lower emissions than distributors.
They also reduce engine complexity and weight by eliminating the need for a distributor, a single coil, and long spark plug wires. Coil packs are compatible with modern engine technologies such as variable valve timing (VVT), direct injection (DI), turbocharging (TC), etc.
They are mainly used in older or custom vehicles with carburetor or throttle body-injected (TBI) engines.
Distributors are also preferred by some enthusiasts who like the classic look and sound of a distributor ignition system.
Now, in this subsection, let’s go through some common questions regarding this comparison:
Q1. How much higher voltage can coil packs generate than distributors?
Coil packs generate up to 50% higher spark voltages than distributors, typically 40-45kV versus 20-30kV. This results from lower secondary resistance in coil-on-plug designs lacking long spark plug wires.
Q2. Can a distributor ignition system be upgraded to coil packs?
Yes, upgrading from distributor to coil pack ignition is possible. But it’s labor intensive, requiring replacing the distributor with coil packs, adding an ECU, new plug wires, and potentially further modifications.
Q3. Coil packs versus distributors: Which one can damage the engine if it malfunctions?
Both can potentially damage engines if they severely malfunction. Failed coil packs can misfire constantly, producing excessive unburned fuel that overheats and washes down cylinder walls.
Distributor failures like stripped timing gears or broken advance weights can cause mistimed sparks, resulting in a detonation that can damage pistons.
At last, it’s clear that coil packs have an advantage over distributors in almost all aspects. So, here are some head-to-head, key factors worth remembering: Coil packs offer more precision for timing control and produce higher voltage and current output than distributors. So they have more spark energy.
What’s more, coil packs require less frequent maintenance and service than distributors. Therefore, coil packs are more reliable than distributors. As such, coil packs are predominant in modern vehicles today.