The 6 Best Catalytic Converters
A Catalyst For A Friendlier Environment
But it's primarily the use of catalysts that allow the converter to do its magic.
Most of us can relate to the experience of being stuck in bumper-to-bumper traffic during rush hour and seeing all that gross haze and air pollution emanating from the exhaust pipes found in a sea of automobiles. In one sense, the internal combustion engine is a marvel invention that has helped people get from one place to another with ease and efficiency. In another, this same invention is a rather dirty piece of hardware due to the harmful chemicals present in its exhaust when it's operating. Fortunately, many cars today are fitted with a device specifically-dedicated to reducing those harmful emissions by converting the poisonous chemicals into more environmentally-friendly gases that won't make you choke on the highway. This device is the catalytic converter.
While many pollutant gases consist of potentially problematic molecules, these molecules are made up of simpler and relatively harmless atoms. It is the job of a catalytic converter to help break these molecules down into smaller components and rearrange the atoms into less harmful substances once they leave a car's engine. Bolted to the underside of a car and located between the engine and tailpipe, a catalytic converter is a large, stainless steel box acting as an emission control device that's responsible for converting toxic pollutants, like carbon monoxide and nitrogen oxide, into less harmful gases before they're released into the atmosphere. The catalytic converter has several components that include a ribbed stainless steel body, ensuring durability and minimal distortion or expansion; substrates (also known as catalysts), acting as the backbone of the unit by driving the conversion process; a cushioning mat, responsible for holding the substrates in proper alignment and creating a seal between the substrates and body; body and pipe heat shields, designed to deflect excess heat away from a vehicle's undercarriage; and oxygen sensors, which monitor the converter's oxygen storage efficiency. The converter also has both an input and output pipe. The input pipe is connected directly to the engine and takes in the heated, polluted gases coming from the engine's cylinders. The output pipe is connected to a vehicle's exhaust pipe where the converted gas and water ultimately exit. But it's primarily the use of catalysts that allow the converter to do its magic.
Built to increase the speed of pollution removal from inside the converter and made from platinum or a similar metal like palladium or rhodium, the catalysts coat an internal, honeycomb-like ceramic core through which pollutant gases flow when they leave the engine. This honeycomb structure maximizes the degree of physical contact between gases and catalysts, allowing the gases to be converted as quickly as possible. A catalytic converter usually has two catalysts. One of them is responsible for breaking up nitrogen oxides into harmless nitrogen and oxygen gases through a chemical process known as reduction (i.e. removal of oxygen). The other catalyst works through an opposite chemical process called oxidation, which converts carbon monoxide into carbon dioxide through the addition of oxygen. A second oxidation reaction converts unused hydrocarbons from a vehicle's exhaust into carbon dioxide and water.
Catalytic converters are available in both two and three-way designs. Typically used in most diesel engines, two-way converters only perform the tasks of the two oxidation processes described above, while three-way converters have the additional advantage of performing both oxidation and reduction, resulting in superior emission control for most gasoline-powered engines.
Ensuring Safety And Compliance
Regardless of the type of vehicle you may be driving, there are several practical considerations to keep in mind when selecting the appropriate catalytic converter.
The first thing you'll want to do is narrow your search to those converters that actually fit your vehicle's make and model. You can often shop for a converter on a website that gives you access to this type of information before making a hasty decision.
Next, you'll need to identify the emissions level for your vehicle.
Next, you'll need to identify the emissions level for your vehicle. Most emissions-compliant vehicles are equipped with a Vehicle Emissions Control Information label in their engine compartments that shows a factory OBDII emissions certification.
Depending on the certification, you must identify the proper converter grade you'll need. Three of the most common converter grades include standard, heavy metal, and OEM. For pre-OBD II vehicles (made in 1995 and before) and vehicles registered outside of the states of California, the standard grade is recommended. OEM grade is recommended for cars meeting the emissions standards set forth by the California Air Resources Board.
Once you've identified the proper converter grade, the final decision to make is whether you prefer a direct-fit or universal-fit unit. Direct-fit converters are designed for installation without any additional modifications, whereas universal-fit converters may require additional cutting, welding, and fabrication before installing them.
A Brief History Of Catalytic Converters
Up until the 1940s and early 1950s, a steady decline in air quality within major cities throughout the world sparked the need for some type of solution to the growing pollution problem. It was French chemical engineer Eugene Houdry who was credited with the development of the first catalytic converter in 1950, later having filed a patent for the device by 1954. Previously, Houdry had also invented catalytic cracking, the industrial process by which the many large and complex organic chemicals in petroleum could be separated into dozens of useful products, including gasoline. However, catalytic converters were essentially poisoned by the lead additives used in gasoline to improve a car's performance.
By 1973, the United States Environmental Protection Agency released a report detailing the health dangers of lead, resulting in the gradual removal of the harmful metal from gasoline. It was after this time that practical catalytic converters were engineered, including three-way converters.
Modern catalytic converters are designed to meet current emission safety standards with a primary goal of preventing excessive air pollution that would otherwise contribute to smog and decreased air quality, particularly in major metropolitan areas.