In a reciprocating gasoline engine, power is created by a sequence of events as a piston travels up and down inside a cylinder. Near the top of the compression stroke, a mixture of air and fuel is compressed in the engine's combustion space above the piston. Once the piston has reached a specified point during the compression stroke (typically just before TDC piston position), the compressed gases are ignited by a spark from the plug's tip (or electrode). When this combustion occurs, an incredible amount of energy is released in the form of expanding gases. Because it is attached to the engine's crankshaft with a connecting rod, this downward movement of the piston creates the rotational energy needed to propel your vehicle.
Better Burn of Air-Fuel Mixture
Today most car, truck and motorcycle engines use a 4-stroke combustion cycle to convert fuel into power. During the fourth cycle of strokes (intake, compression, power and exhaust), no spark occurs. Any unburned gases are delivered to the atmosphere during the exhaust stroke, after which the intake stroke follows to provide a fresh air-fuel charge. Unfortunately, both 2-stroke and 4-stroke engines emit hazardous, unburned fuel residues into our atmosphere. Consequently, the power generated by the engine and the amount of unused fuel exhausted are dependent upon the effectiveness and completeness of the burn.
The Path for Going "Green"
During the engineering research, E3 discovered that the electrode on a typical J-wire plug utilizes a single sharp edge that often wears much too fast. The company's conclusions led to the development of a diamond shaped design with a center electrode tip that exposes multiple edges to the engine's combustion space. Since electrical impulses naturally follow the path of least resistance, this made it easier for E3's new electrode design to provide a well-formed spark. When tested, this configuration resulted in a better burn of the compressed air-fuel mixture before the beginning of the exhaust cycle. By lowering the emission of unburned gases, E3 had discovered its path for going green.
Reduction of the Coefficient Variance
Engineering scientists studied the actual pressure rise from a single combustion event with different spark plug designs. The measurement is called the Indicated Mean Effective Pressure (IMEP). This value is determined by running a series of combustion cycles and comparing the values from one spark plug to another, keeping all other parameters (load, rpm, temperature, humidity, and related factors) equal. Double-blind tests were run comparing the area under the pressure curves itself for 500 combustion cycles per spark plug design. Then, E3 refined its electrode design to reduce the Coefficient of Variance (COV) for a series of combustion cycles. This research work was initially performed at the company's test labs in Atlanta, and continued with further development and evaluation at Georgia Tech and Michigan State University's Engine Research Laboratory.
The unique electrode created by E3 incorporates the combined benefits of several known performance plug types as well as new science based upon years of spark plug research. There are three main performance components that determine how the E3 DiamondFire configuration works:
Open Ground Electrode Design
The first component mimics surface gap spark plugs (like the type used in rotary engines), which directs the flame kernel to the piston (or rotor) more directly. This was done to reduce the travel time from the spark zone to the chamber containing the compressed gases. By opening the section at the top of the electrode, E3 avoids creating the "doughnut" shaped flame kernel produced by standard plugs. Given the short amount of time available to get combustion started, the faster you can direct the flame to the area above the piston, the better.
Forward Projection into Spark Zone
Secondly, with retracted plug designs, the generated spark lies against the top of the combustion chamber surface. So, E3 engineers designed the electrode to project farther forward into the combustion chamber. This brings the spark zone closer to areas of probable good air-fuel mixture. The outward projection also creates beneficial "micro-aerodynamics" within the spark zone. Since the initial combustion wave leaves the spark area at supersonic speeds, the elevated edge of the E3 electrode provides somewhat of a chimney effect as the next air-fuel mixture is drawn into the spark zone.
Edge-to-Edge Spark Discharge
Lastly, the strongest part of the E3 electrode design is the forced edge-to-edge spark discharge, which was proven to be the best way to direct a spark as it leaves the electrode's surface. The E3 design improved upon the phenomena that race car drivers used for years. They would "cut back" ordinary spark plug electrodes to improve the overall spark discharge. Since the spark itself occurs only when an avalanche of electrons migrates from the two electrodes (cathode to anode), sharp edges proved to be better at initiating electron migrations, and these accelerated electrons would collide with matter inside the spark zone to release additional electrons.
As a result, the E3 advanced electrode works to create a plasma channel through which the spark current flows more easily. That helps the E3 multiple-edge configuration to outperform all other spark plug designs available, including many premium offerings from the major manufacturers.
Problem with "J-Wire" Electrode Design
Some competitive spark plugs feature problematic designs like the traditional J-wire where the ground electrode can actually get in the way of the flame kernel as it travels away from the plug's gap. This can sometimes interfere with the combustion of the compressed air-fuel mixture. To ensure a more complete combustion, E3 recognized that the flame front must reach the compressed gases as quickly as possible. That is why the E3 DiamondFire design is open at the end. E3 flame kernel can travel directly toward the remaining air-fuel mix.
"Fine Wire" Precious Metal Electrodes
Manufacturers of spark plugs that use precious metals in their electrode were quick to look for ways to reduce production costs. Thus, the "fine wire" electrode was introduced to reduce the amount of metal used to produce their premium plugs. The challenge was the fine wire design wouldn't have a very long useful life, so platinum or iridium was added to help extend the useful life of the plug. Because of their basic design modifications, fine-wire spark plugs have fewer misfires. But, the E3 DiamondFire design with its multiple exposed edges still outperforms fine-wire plugs by maximizing the spark presentation in the combustion chamber.
A Faster Electrical-to-Chemical Transfer
E3 feels their most significant research discovery came from understanding that having two sharp edges firing to each other is an improvement over an edge-to-flat electrode design. Sharp edge-to-edge designs force the electrons to form a stronger plasma channel faster. That lets the E3 DiamondFire spark plugs reduce ignition delay and offers a measurable improvement in the electrical-to-chemical energy transfer. If you're looking for a faster flame, a more complete combustion, an improved engine response and higher fuel efficiency, remember E3 spark plugs are "Born to Burn."
Spark Breakdown: Ignition Delay
The E3 engineers started with the flame kernel that is created when a spark is initially created in the cylinder's combustion area. Once this event occurs, the compressed mixture has to be ignited by contact with the flame front initiated by the spark, an increase in cylinder pressure and/or an increase in temperature. For perfect combustion to occur, all of the compressed fuel mixture would have burned at the point where the piston created a constant volume inside the cylinder. In reality, E3 recognizes that there is always a delay between the initiating spark, flame kernel growth and movement of the flame front throughout the combustion space.
Better Conductive Heat Transfer
Immediately following the spark event in the combustion zone, a critical flame kernel is formed. To ignite the residual gases before the exhaust event, an engine is designed to increase the temperature of the remaining gases, raise the cylinder pressure and expose the unburned mixture to the flame front. E3 quickly realized a larger kernel is exponentially effective because it offers more mechanisms for heat transfer. Since the larger ball of the flame has more surface area, the conductive heat transfer to the unburned gases is greater and faster. Also, a larger flame front impacts the convective heat transfer by tumbling the remaining air-fuel mixture and exposing more of the unburned gases to radiant heat transfer.
Improved "Mass Fraction Burned"
This means that just a slight increase in flame kernel strength can cause a cascading improvement in the entire combustion process. By getting the flame process started earlier, the mass fraction burned at any given crank angle position away from TDC is increased. Since the exhaust valve opening occurs at a fixed point in the crankshaft's position, E3 understood how important it is to get as much of the fuel burned before it is vented off during the exhaust cycle. So, to increase power and reduce emissions, the company created the DiamondFire electrode designed to burn more of the existing air-fuel mixture present in the combustion chamber.
By measuring the pressure inside the cylinder while the engine is running, very accurate details of the combustion process can be analyzed.
The graph below plots ignition voltage (blue line) and cylinder pressure (red line). The blue line starts to rise as the piston moves upward (all valves closed) starting compression. At the right moment, usually around 28° before Top Dead Center (TDC), the ignition system sends voltage to the spark plug. There is a lag of a few milliseconds from the time the current is sent to the spark plug and when the spark actually starts combustion. This is called the ignition delay. Once combustion starts, the pressure rises rapidly and peaks after TDC. This puts max pressure on the piston when the connecting rod is at the best leverage angle to the crankshaft. During the power stroke, the combusted gases expand and push hard on the piston. At a certain point, the exhaust valve opens and vents off the pressure in the cylinder, meaning that no more work is done on pushing the piston.
A cylinder pressure graph reveals some interesting information. First, notice the peak pressure and area under the pressure curve as created by different spark plugs. All the power an engine makes comes from the area under this pressure curve. If a spark plug can create higher average pressure for every combustion cycle, it makes more power.
Power improvements are shown on an engine dyno, but that measurement occurs later in the combustion process. The most accurate and sophisticated way to measure power is to look at the cylinder pressure over a number of cycles (such as 500 cycles) and compare one modification to another. Since the flywheel integrates the cycles over time, and the individual pulses of each combustion event are lumped together, subtle improvements are hard to determine. For optimal tuning, major race teams from NASCAR to Formula 1 are now equipping their cars for in-cylinder pressure measurements. E3 engineers have been using this practice since the mid 1990s.
The following graph shows how the E3 spark plug creates higher pressures in a test engine, compared to a standard spark plug. The higher and more consistent pressure levels directly result in more power and potentially less emissions, while burning more of the available fuel and requiring less throttle pressure which leads to increased fuel economy. More fuel is converted to power, driving the piston downward more efficiently and less fuel escapes through the exhaust. This is at the heart of the substantial performance improvement resulting from the E3 DiamondFire design.
Another important observation is the variation of peak pressure values from one combustion cycle to the next. Surprisingly, not all combustion cycles make the same power. An engine running well can still have a 5% drift in peak cylinder pressure values from one power stroke to another. A poorly running engine will have 10% or more. This is called the coefficient of variability and can be seen in the next graph. Some combustion events result in high pressure production, others result in low pressure. The graph shows successive combustion events taken in real time, showing how cycles vary from one another even while the spark plug is firing very well.
The graph below shows how E3 spark plugs improve pressures over a series of combustion cycles and how this adds up to better power. The blue line was measured over a successive number of power cycles using E3 spark plugs. The pressure peaks are higher and more uniform than the standard spark plug (shown in the blue line). The dotted lines represent an average of the pressure curves. The blue dotted line shows the running average of the E3 spark plug pressure/power production. The dotted red line shows a lower average for the standard spark plug.
The graphs show that the E3 DiamondFire design produces more consistent and higher combustion pressures as an average over successive combustion events. This leads to more net power, and helps reduce emissions and improve fuel economy. Pressure traces of this sort show up in every engine E3 has tested since 1997.
E3 researchers have performed this type of analysis and measured consistent improvement in automotive engines, small two stroke engines, and high-performance four-stroke engines, etc. Creating a faster flame front and a quicker combustion pressure rise results in more complete combustion, and this directly improves engine performance.