Heating the fuel was after the carb. I believe they used a heating element underneath it. Anyway the other article that I remember was in Hot Rod. They were talking about this guy who had a 327 Chev with hollowed out exhaust seat. The fuel would flow through there and get super heated. There was small pin holes in the exhaust seat that when the valve open would jet out fuel. To make this work he needed variable valve timing. The longer the valve stayed open the more RPM. At the end he had 450 hp and using 70% of the fuel more efficiently= more MPG. He also had less emmisions