Rotary engines have a problem not found in reciprocating piston four-stroke engines in that the block housing has intake, compression, combustion, and exhaust occurring at fixed locations around the housing. In contrast, reciprocating engines perform these four strokes in one chamber, so that extremes of "freezing" intake and "flaming" exhaust are averaged and shielded by a boundary layer from overheating working parts. The use of heat pipes in an air-cooled Wankel was proposed by the University of Florida to overcome this uneven heating of the block housing. Pre-heating of certain housing sections with exhaust gas improved performance and fuel economy, also reducing wear and emissions.