E3 Spark Plugs

There has always been historical disagreement as to the inventor (Edward Berger versus Sir Oliver Lodge) and date that the first electric plug was used to spark the air/fuel mixture in an internal combustion piston engine. What we do know is the U.S. Patent office began issuing patents to protect a variety of ignition products in the late 1800s. Among the early engineers seeking protection for their ideas was Nikola Tesla for his ignition timing system. The early plugs relied on magneto-based ignition wires to provide the electrical flow that a plug requires to do its job. For the majority of vehicles on the road today, an ignition coil rather than a magneto is used to amplify the voltage traveling through an engine's ignition wires. However, both provide an effective high-voltage electrical spark. Once the voltage created by a magneto or ignition coil exceeds the dielectric strength of the gases in the motor's combustion chamber, an explosion occurs and the piston is send downward completing a cycle. At the end of the spark event, a small flame kernel remains as raw gases continue to burn. This is where E3's DiamondFire technology helps to reduce the amount of unburned gases emitted into the environment when the exhaust valves are open. You can read more about ignition theory and combustion cycle analysis in the Technology section of this website.

Components of Modern Spark Plugs

There are numerous spark plug designs available from online vendors, big discount stores and auto parts dealers. To better understand the differences between various types, it is important to understand how a plug's design impacts engine performance, thoroughness of combustion and the durability of the spark plug itself including:

Terminal - Opposite the threaded end of the plug is the terminal cap. For most cars and trucks, the rubber boot at the end of each ignition wire can be firmly pushed over the terminal's barrel-like tip. However, the barrel shaped connector can be unscrewed for installing ignition wires that used an eyelet connector, which is rare on today's street vehicles.

Shell - For most people, the shell is the most obvious feature of the traditional spark plug. The shell is a ceramic outer casing that is fitted into the threaded metal housing at the end of the plug where the ground electrode is found. Typically white in color, the shell may or may not include ribs but usually includes a brand name, logo or set of identifying numbers printed on the outer surface.

Ribs - The length of the shell and the number of ribs both play a role in the determining how and when the high voltage ignites the fuel mixture inside the engine. Since the central electrode and insulator run the length of the plug, ribs improve insulation and prevent electrical energy from leaking out before it reaches the ground electrode and creates a spark.

Insulator - The central electrode that runs from the terminal connector to the base of the spark plug is surrounded by an aluminum oxide ceramic like the upper portion of the plug's shell but is not glazed. A longer insulator may protrude past the base of the metal shell but must be short enough to avoid contact with the top of the engine's piston. The length of the insulator and the metal conductor core help determine a plug's heat range.

Central Electrode - From the terminal cap, the electrical charge passes through the metal conductor core to deliver the spark that ignites the gases in the engine's combustion chamber. After the mixture explodes, the plug emits heat away from the engine (thermionic emission) via the same conductive core. Virtually all spark plugs use a copper-core center wrapped in nickel, platinum or iridium to conduct the electrical charge, jump the gap, and promote efficient heat dissipation.*

*NOTE: Precious metals like platinum, silver and gold are not used on central electrodes for improved electrical conductivity. Since these high value metals have a higher melting point, the center wire can be smaller in diameter and still provide acceptable durability.

Metal Shell - The metal jacket that contains the threads allows the plug to be screwed into the engine's head. Most plugs have a specific torque requirement to ensure a tight fit without damaging the female threads in the engine. Ideally, anything that has a torque value should be torqued to that value to ensure a precise seal. The metal casing also serves multiple functions as it passes heat from the insulator to the cylinder head and acts as the ground for the electrical spark traveling through the central electrode. The length of the threaded portion of the metal case must match the thickness of the head to avoid internal damage to the piston.

Electrode Tip Design - Electrons are emitted from wherever the radius of curvature of the surface is the smallest, which is where the electrical field is the strongest. Ideally, a pointed electrode would be the most efficient in flow but would quickly erode due to heat. A traditional J-gap ground electrode design evolved to maximize flow to an edge rather than a flat surface. However, the less amount of material near the gap the more rapid growth of flame kernels.

Born to Burn - Over the years, manufacturers have attempted to design a spark plug that can provide better ignition and longer life. The traditional multiple side electrode and J-gap plug designs offer durability but shield part of the flame face as the fuel mixture burns in the engine's combustion chamber. This can result in less burn, increased emission of unburned gases (or raw fuel), and reduced gas mileage. E3's DiamondFire design utilizes a forced Edge-to-Edge spark discharge to better initiate electron migration inside the spark zone and to withstand the wear and tear of both highway and city driving.

E3 had independent labs conduct tests on a variety of plug designs to determine the influence of the ground electrode on flame kernel formation, cycle-to-cycle variation and overall performance. This research led to a multiple-edged tip that can lessen obstruction for flame propagation with a lesser mass of metal to reduce heat loss from the flame kernel. In other words, our DiamondFire plug was "Born to Burn".