Performance & Hotrod Business February '14

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Catalytic Converters HOTROD Left: A cross-sectional view of Eastern's Bullet Cat metal foil substrate. A special nano-coating process is used to apply the precious metal catalysts. (Courtesy Eastern Catalytic) Center: In addition to converter availability for custom installations, several manufacturers also offer a complete pipe and converter bolt-on system that features performance converters. This Mustang application also features a crossover H-pipe. (Courtesy Eastern Catalytic) Right: Converters that feature ceramic honeycomb substrates include a special matting that is wrapped around the substrates, in order to provide substrate support within the casing. When assembled, the matting provides a relatively loose fit. When the converter experiences its first heat cycle, the matting expands, filling any voids and providing a durable circumferential support for the substrates. If the converter is not broken-in properly, the matting may not be able to expand fully. Many installers may be unaware of the need to follow a proper break-in, which can maximize the potential for matting expansion. (Courtesy Eastern Catalytic) in a cylindrical shape and then wrapped in a smooth-surface foil that is brazed to the cylindrical housing. This style is ideal for severe applications that feature high-compression naturally aspirated engines, engines that are equipped with nitrous injection or engines that feature a forced induction system such as turbocharging or supercharging. Is the Converter Working? Since the chemical reaction that takes place within the converter requires a high level of heat, a quick and easy way to determine if a converter is working properly is to monitor the surface temperature of the converter's entry and exit (for instance, at the front weld ring and rear weld ring of the converter). A simple way to do this is with an infrared pyrometer, by measuring and comparing the level of heat at the converter inlet and outlet. However, since the converter may not be hot enough at idle to obtain an accurate assessment, the reading should be taken with the engine revving at around 3,000 rpm or so. This is best done on a lift with the vehicle properly secured. The temperature at the inlet of the converter should be in the area of 300 to 350 degrees. The exit of the converter should be approximately 100 to 150 degrees higher than the temperature of the converter inlet (the converter needs to reach around 350-500 degrees internally in order for it to begin to "light off" and perform the necessary emissions conversions. Internal temperature can climb much higher during the conversion process). For example, if inlet temperature reads 350 degrees, outlet temperature should read around 450-500 degrees. (Note: Don't measure temperature of the converter body or heat shield. Measure temperature only at the inlet neck and outlet neck of the converter. The converter weld rings are typically good locations for taking your temperature readings.) If the front inlet of the converter isn't reaching proper temperature (if temperature is below 300 degrees), this indicates that the converter won't be able to "light off " and perform the necessary chemical conversion of emissions gasses. This could indicate that the engine is running with an improper air/fuel mixture, and/or that the converter substrate is contaminated with oil or coolant. If the rear (outlet) of the converter temperature is excessively high (let's say 350 degrees or more higher than the temperature at the converter inlet), this can indicate that the 54 n Performance & Hotrod Business PHBFEB_52-77.indd 54 n converter is working too hard, trying to compensate for an out-of-balance air/fuel mixture (for example, if inlet temperature is 350 degrees and outlet temperature is 700 degrees). If the converter continues to operate at an excessively high temperature, the substrate will eventually be damaged, resulting in internal blockage and restriction. An infrared pyrometer is an indispensable tool that should reside in every shop's tool arsenal. This type of temperature gauge is useful for a number of system areas, such as radiator inlet and outlet hoses, monitoring when a thermostat opens, brake temperature, tire temperature immediately following a hard run on a road course or autocross course or before and after a burnout on the drag strip, transmission case or transmission cooler line temperatures, etc. Converter Break-In Period Don't just install a new converter and hit the road. Many people are unaware of the need for a proper break-in. Just as a new flat tappet camshaft or a new set of piston rings require a break-in period, so does a new catalytic converter. Attention to this break-in period is essential in order to ensure the long-term stability of the substrate. The break-in involves the thickness of the matting that is wrapped around the sub- February 2014 1/7/14 2:15 PM

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