Performance Distributor’s HEMI Coil Pack Design: A Vast Improvement

Ignition coils aren’t exactly new technology, and yet somehow the modern variety remains a mystery to many hot rodders. So, let’s start at the beginning, and then we can get into how modern aftermarket companies like Performance Distributors (PD) are improving on factory designs.

For older hot rodders, this may be ancient history, and for younger folk, this may sound like a snoozefest, so I’ll save you the drawn-out explanation. But, for argument’s sake, you’ll find an ignition coil is, at its core, (no pun intended), an induction coil for a car’s ignition system. Basically, it uses its primary and secondary coil windings to transform the current of electricity coming from a car’s battery via the ignition switch into the thousands of volts the spark plugs need to ignite the fuel mixture in the combustion chamber.

A modern engine’s ignition system is much different than in days past, but the same basic principles remain. If you want to put power to the pavement like this, you’re going to need a solid system!

In classic vehicles, a mechanical contact breaker, points, and condenser were standard to accomplish this, but we’ve come a long way since then. Nowadays, ignition systems use a transistor to provide pulses to the ignition coil or coils. In the case of the modern engine like, say a gen-three HEMI – it’s eight coils for each engine cylinder.

Those coils contain a primary winding which consists of a few turns of thick gauge wire. The secondary winding is made up of thousands of turns of thin gauge wire. On a modern Mopar engine like a gen-three HEMI, the electrical current passes through a capacitor before moving on to the primary and secondary windings of the ignition coils which increases the number of volts sent to the spark plugs.

Ignition components are often overlooked by enthusiasts because many people think the stock parts are adequate, but little do they know there’s much to be gained by upgrading something as simple as ignition coils. Especially if you’re planning on upgrading to a more aggressive camshaft!

So, why is this important, and what does all of this mumbo jumbo mean for someone looking to increase the performance of a modern ignition system? Well, even though factory coil design and technology is a far sight better than the ancient systems of the past, that doesn’t mean they still can’t be improved upon.

We called up the experts at Performance Distributors to find out what options enthusiasts have to upgrade an ignition system. We asked them about modern Mopar, specifically, but the same applies to most modern powerplants. When we spoke with Brian Caruth of Performance Distributors, he enthusiastically jumped right into the SOS Coils PD offers for modern HEMI’s, and what makes them so great.

When we asked the experts at Performance Distributors what people could do to upgrade the ignition systems on late model Mopars, they immediately answered with the SOS HEMI Coils.

Brian said, “the HEMI SOS Coils are designed as an exact factory replacement for the stock Mopar coil on plug systems. Our SOS (Sultans of Spark) Coils mount in the OEM location and plug into the factory wiring harnesses with no modifications. The HEMI SOS Coils pack a more powerful punch over the factory coils as they are designed to produce 40kv (40,000 volts) of spark energy from each coil. This is a 15-20% increase over the stock ignition.”

“Our engineers were able to achieve this by increasing the primary and secondary coil windings. With higher voltage, the coil can produce a spark strong enough to jump a wider air gap at the spark plug. This is why we recommend opening the plug gaps from .044″ to .065″. In addition, the dwell is set higher in the SOS coils which hold the spark at the gap for a longer period of time in the crankshaft rotation. This greatly improves throttle response and low-end performance. Overall, the SOS Coils increase horsepower, torque, and improve fuel mileage.”

We told Brian, that sounds great and everything, but what exactly does it all mean? The barrage of useful information is only useful if you understand how it all works, so we launched into a series of questions that allowed Brian to break it down Barney-style for us.

SM: What exactly does it mean to “Increase the primary and secondary coil windings?

BC: Our engineers were able to increase energy output and secondary voltage by using optimized and improved primary and secondary windings. The primary windings have reduced inductance and resistance which allows the energy to flow more efficiently through the windings. This provides a faster rise time with less loss to resistance heating. Inductance is higher in the secondary windings and that helps to create a greater turn ratio which boosts the secondary voltage.

What performance benefits does one gain by opening up a spark plug’s gap?

BC: Opening the gap to .065″ exposes more of the spark kernel to the fuel mixture for a rise in the burn rate. This reduces the amount of unburned fuel exiting through the exhaust normally associated with a smaller plug gap (stock coils). This unburned fuel is now combusting more efficiently for horsepower and torque gains, as well as improving fuel efficiency and reducing hydrocarbons.

With the dwell set higher, which holds the spark at the gap for a longer period of time in the crankshaft rotation, does that create an opportunity for even more performance gains if used in combination with a more aggressive camshaft?

BC: Absolutely! More aggressive cams have extended duration and higher valve lifts which equates to more fuel in the combustion chamber. The best way to maximize this additional performance is by maximizing the spark.

So, there you have it. A little history and a short explanation as to how modern ignition systems work and how they can be improved upon. If you have any questions about your vehicle’s ignition system, be it new or old, give the folks at Performance Distributors a call, and they’ll sort you out. They’ve been in the game long enough to be experts on modern and classic coils.

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About the author

Vinny Costa

Fast cars, motorcycles, and loud music are what get Vinny’s blood pumping. Catch him behind the wheel of his ’68 Firebird. Chances are, Black Sabbath will be playing in the background.
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