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Tech Review—E3 Racing DiamondFIRE Ignition Products


By Miles Cook

Photography Courtesy of E3 Spark Plugs

As testament to how time flies so quickly, it’s worth noting that the E3 Racing brand has been around for more than 20 years. Since 1997, E3’s main focus has been studying our beloved internal combustion engines by researching ways to improve combustion efficiency, and it didn’t take long for the engineering types at E3 to realize that one component that hadn’t been rethought for a while was the spark plug. So, for the next seven years E3 looked closely at designing a better plug. And in 2003, E3’s DiamondFIRE plugs were a new way of looking at spark plugs.

Since then, E3 has developed a complete line of automotive plugs for nearly all pushrod GM, Ford and Mopar engines, as well as all the popular overhead-cam Ford engines including Ford’s favorite son, the high-revving DOHC Coyote 5.0.

Within the last three years E3 is has become a manufacturer of a complete line of ignition-related products that just begins with the spark plugs, and now envelops the whole ignition system to include plug wires, distributors, ignition boxes, and coils. Also included in the mix are accessories such as an available external two-step rev limiter and a tach adapter. Our purpose here is to provide an overview of all of E3’s available high-performance ignition-system goodies. Let’s take a look.


Complementing the E3 spark plugs is a new line of DiamondFIRE racing plug wires. These 8.5-mm racing plug-wire sets are designed to optimize the power of E3 plugs. Sporting a class F40 spiral conductor and rated at only 40 Ohms per foot, the 8.5-mm silicone outer jacket encases a silicone inner-jacket with stainless-steel terminals. Available in universal and engine-specific as well as shown sleeved or unsleeved configurations, the E3 wire sets offer a high-silicone content rating to provide high-level heat protection and performance. Applications include several fitments for small- and big-block Chevys, as well as for GM LS engines and small-block Fords. There are also the aforementioned universal sets with a straight- or 90-degree- boot as well.


E3’s line of DiamondFIRE distributors are engineered for street performance and racing environments and are built to exacting tolerances with numerous features. They include a race-proven adjustable mechanical advance that features a cam plate and weights that are precision stamped and blanked for precise accuracy of dimension and balance. E3 TIG welds the cam plate to the top of the shaft assembly for reliable performance and long-term durability. The weight pivot pins are also stacked and TIG welded in place on the cam plate. The whole assembly also receives a proprietary nitrocarburized treatment, which significantly strengthens and hardens the surface, while reducing friction and providing a corrosion resistant finish. The cam plate has nylon rub pads on which the weights ride, thereby ensuring a smooth advance movement over time.

All E3 distributors comes with three sets of advance springs and four stop bushings, allowing you to customize the advance curve to a specific application. The high-output magnetic pickup is engineered specifically for racing and is bolted to the base of the distributor. The shaft mounted paddle wheel reluctor has been finely tuned to enable the whole system to generate an accurate trigger signal at all engine speeds including up to redline. The centerless ground shaft rides on an upper sealed roller bearing with an extra-long lower bronze Oil-Lite bushing for smooth operation at high rpm.

All E3 distributors also feature CNC-machined 6061-T6 heat treated aluminum housings. A special hot-forging process goes beyond the normal billet process to ensure there are no weak spots or porosity while producing the strongest possible flex-free parts. Available applications include Chevy and GM HEI as well as a number of Ford part numbers for 221-302, 5.0 TFI, 351W, 351C, 400M and 429/460 engines.

Ignition Box

The E3 DiamondFIRE 6CDI digital capacitive discharge ignition box has high-performance digital microprocessor-controlled circuitry contained in a lightweight extruded aluminum housing. Boasting a highly efficient design, the 6CDI’s features include: a draw of only 0.7 Amps per 1,000 rpm of engine speed, delivery of 525 volts to the coils, up to 130mJ of spark energy, a sequential (not random) fire-start mode for easier/faster starting, production of a multi-spark up to 3,000 rpm for faster acceleration and improved throttle response. A single-state digital rev limiter can be set in 100-rpm increments up to 9,900 rpm. The E3 6CDI comes complete with a wiring harness, hardware and a mounting kit. It’s compatible with even-fire 4-, 6-, and 8- cylinder engines and 12-volt negative-ground electrical systems. It will accept input trigger signals from break points, breakerless electronic modules as well as magnetic distributor or crank-trigger pickups. The E3 6CDI is not designed for systems with Hall-Effect pickups.


The DiamondFIRE high-output CD coil is specially engineered to work with the 6CDI ignition system. The design of the E-core and the use of heavy gauge windings produce a high-voltage step-up transformer to ensure the fastest possible delivery of the most energy to the spark plug. Highlights include it being shock and vibration resistant. Its high-temp epoxy provides excellent thermal conductivity and an extruded aluminum housing provides optimum cooling, while a superior boot/terminal design protects from arc-over. The E3 coil will also works with other popular 6 series street/strip CD ignition boxes. There are also coil-over-plug (COP) applications for late-model GM LS, two-valve modular and Coyote 5.0 Ford and Mopar Hemi applications.


E3 has an external 2-Step rev limiter that enables setting a lower rev limit when in the starting and staging lanes. Two easy-to-read rotary dials allow you to set the staging rev limit in 100-rpm increments while a bright LED indicator lets you know the unit is on and functioning even in low-light conditions. It works in conjunction with the built-in rev limiter in the 6CDI. The E3 tach adapter is designed to correct the operation of most voltage-triggered tachometers that do not work properly when a digital capacitive ignition box has been installed on the car. This occurs because the voltage-triggered tach does not work directly off the tach output terminal of the control module. Finally, E3 also offers an 02 sensor as well.

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Mike Galimi
Mike Galimi is the Director of Content & Marketing at ProMedia Publishing and Events with nearly 20 years of experience in motorsport writing and photography.