Stephen Cox blogs about the growing four-cylinder trend in grassroots racing. Once upon a time, entry level stock car divisions at local bullrings across the country were filled with the glorious growl of American V8 engines. They were called “Hobby Stocks,” “Pure Stocks” or “Street Stocks.” A few unimaginative promoters condemned them as “Bombers” or “Thundercars,” as if any fool would want to drive a car so named.   But regardless of the title, entry-level stock car fields at lo...