The spark plug was first developed in 1860 by Etienne Lenoir in his first internal combustion engine, but it wasn’t until the invention of the commercially-viable high voltage spark plug as part of a magneto-style ignition system by engineer Gottlob Honold in 1902 that the development of the internal combustion engine was made possible. Since that time, the basic principle of the spark plug has remained largely the same. Until now, that is.
The folks at Pulstar boast a line of plugs that aren’t your average spark plug. These Pulstar plugs are claimed to be designed to not only deliver additional horsepower and torque, but increase fuel economy as well. To learn more about these radical plugs and how one can best select the proper plugs, we sat down with Pulstar founder and President Lou Camilli, who could be best described as a walking encyclopedia of science and electrical energy knowledge.
Putting the Pulse In Pulstar
So what is the Pulstar Pulse plug, and what makes it so different from other spark plugs on the market, you ask?
Interestingly, the Pulstar Pulse plug was created not through the inspiration of the automobile, but of science. The Pulse plug applies technology developed at the Sandia National Laboratory in Albuquerque, known as Pulsed Power Technology, which is used to generate and apply energetic beams and high power energy pulses. And through plasma research supported by the scientists and engineers at Sandia derived from ultra-high power electrodynamics, the technology behind the Pulse Plug was born. The result is a plug that Pulstar boasts as virtual replacement for the age-old spark plug.
The Pulse Plug looks like a standard plug on the outside, but on the inside is a capacitor that stores energy each firing cycle and releases it in a high-energy pulse. In essence, Pulstar has completely redesigned how the 100 year old spark plug operates and claims it has made the combustion process far more efficient.
“We took a different approach,” says Camilli. “We thought, why don’t we take the spark and go after the fuel? And that’s essentially what we’re doing.”
And while the Pulse Plug may look like your ordinary spark plug on the outside, it’s what inside that matters. With the Pulse Plug, electrical energy from your engine’s ignition coil is stored in a capacitor within the plug, which is released in a powerful and quick two-nanosecond high-energy pulse when needed. They claim these plugs incorporate a current peaking capacitor to increase peak spark power from 50 watts in traditional plugs to over 1,000,000 watts of fuel igniting power.
Behind The Technology
Over the years, many attempts have been made to take the spark plug to a new level, but the basic principle has remained the same for more than 100 years. The traditional plug has an insulator and an air gap, and a spark is created. But as Camilli explains, auto makers have for years worked around the design limits of the spark plug, with cam phasing, direct injection, stratified charge, and other modifications to get the fuel into the spark.
This cutaway diagram displays the differences between the Pulse Plug and a traditional spark plug. Where an air gap resides between the resister and gas seal in a spark plug, the Pulse Plug houses a built-in capacitor.
At top, you can see the high-energy plasma discharge of the Pulse Plug upon discharge.
The first law of thermodynamics is you can’t make or destroy energy, you can only change its form. And that’s the principle by which the Pulse Plug operates. Unlike the traditional spark plug, the Pulse Plug claims to stores energy within an internal capacitor during the time of the spark event and is discharged quickly. Explains Camilli, “A good analogy is a flashlight and the strobe on a camera flash. Both use AA batteries, but the flashlight gives off this little beam of light, while the same batteries in the camera flash produce this incredibly bright light; it just doesn’t last very long, because it doesn’t need to.”
All of the energy stored inside the capacitor of the Pulse Plug is coupled to the fuel charge. Essentially, electrical energy has been converted to combustion energy, and by doing so, Pulstar claims it produces more consistent ignition, more complete combustion, shorter combustion time, and a host of other internal benefits from lighting the fuel charge the same way every time relative to crank angle on every cycle.
“Every manufacturer and every ignition designer has their own concept and ideas about the combustion process, and so you have this wide array of operating platforms,” Camilli explains. “And our biggest challenge was to insure that this product would work in all of them.”
We’ve already discussed the methods for producing horsepower and torque increases, but it doesn’t stop there.
But for racing applications, where Pulstar engineers and the end user might have more control over the engine, these benefits could be optimized to gain even greater performance increases.
“The capacitor is what creates all of the benefits,” says Camilli. “When the capacitor discharges automatically and puts all of this energy into the fuel charge, that’s when the flame kernel is created. And if you can create a larger, consistent flame kernel every cycle, that gives better burn time, higher peak pressure, better torque, and all of the other advantages.”
Through 14 years of development derived from plasma research at the Sandia National Laboratory, Pulstar has developed a plug that is compatible with virtually any make and model of production or race engine. A quick browse through the selection guide on the Pulstar website reveals an endless number of vehicles that these variations of plugs are suitable for.
Pulse Plug Selection
Going from a traditional spark plug to the Pulse Plug, one might be curious how to go about choosing the proper plug for their application. So we asked Camilli to assists us in providing a general guide to plug selection for street/strip-type applications.
“First and foremost, start cold,” says Camilli. In general, the higher the performance of the engine, the colder the plug you’re going to want to run.
“In a naturally-aspirated application, if you’re using high octane racing fuel, it takes longer to burn, so you have a longer thermal cycle. Thus, you’re going to want to run a cooler plug.” On the flip side or the coin, an engine with a lower octane that burns faster will allow one to get away with a hotter plug. In the end, the plug selection is determined by the fuel and by the engine and application. With a nitrous combination, Camilli explains to start with their 2 series, which is a 10 heat rating, and then gradually work to a 7, depending on how the plug looks when performing a plug check.
Boosted applications, meanwhile, are always going to use colder plugs, but how much colder is dependent on a number of factors, including how much boost is being applied, the type of fuel being consumed, the RPM level, and how long the engine needs to be under pressure.
The Pulse Plugs are available in a number of different heat ratings for different engine combinations. It's advised to start out with a colder plug for high performance engines and work up. As Camilli explains, the higher the performance of the engine, the colder the plug it's going to need.