THE SHOP

Performance & Hotrod Business February '14

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substrate that the exhaust stream enters first) is typically washcoated with palladium and rhodium and is designed to reduce oxides of nitrogen, while the second substrate (usually washcoated with palladium and platinum) handles the conversion of carbon monoxide and hydrocarbons. The air tube is positioned between the two substrates in order to provide additional oxidizing air to increase carbon monoxide and hydrocarbon conversion. Performance Cats Naturally, the idea of placing anything in the exhaust stream that might restrict exhaust flow and increase backpressure is never an acceptable idea to any performance enthusiast. However, vehicles that were originally equipped with catalytic converters and that are intended for street operation must retain these components in order to comply with emissions regulations. Thanks to the performance aftermarket, we can have our cake and eat it too, by creating an efficient exhaust system while still com- n c . - . Right: Round-profile performance converters are also available in a tubular format. Instead of using a ceramic substrate, a metal foil substrate with larger cells provides both a space-saving and attractive appearance, as well as increased durability for extreme engine applications. This seethrough-view example is Eastern's Bullet Cat. The stainless steel body is easily polished. (Courtesy Eastern Catalytic) Far Right: Performance catalytic converters are available in relatively compact sizes, with stainless steel construction available polished or DIY-polishable. The example shown here is Eastern's Tru Performance converter. (Courtesy Eastern Catalytic) Cutaway view of a three-way catalytic converter with air. The air feed tube injects additional oxygen to accelerate the chemical conversion process. (Courtesy Eastern Catalytic) plying with the law. There are specially designed low-restriction converters that cater to the performance crowd. Performance catalytic converters are available in two "forms," including those that feature a "traditional" converter body and those that feature a round-profile "bullet" or "glasspack" appearance. A performance converter reduces unwanted restrictions by utilizing either an increased number of "cells" or larger cells that are less restrictive. In other words, the "holes" in the converter substrate blocks are larger, with greater surface area. A high-performance converter may feature a substrate that is comprised of either ceramic or a thin corrugated metal foil, either of which is washcoated with the necessary chemical coatings that initiate the gas conversion process. The foil construction (most commonly used in a bullet/glasspack style converter) is wound February 2014 PHBFEB_52-77.indd 53 n Performance & Hotrod Business n 53 1/2/14 4:32 PM

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