Cooled EGR shows benefits for gasoline engines

Exhaust gas recirculation systems now in use on diesel engines are used mainly to meet emissions regulations. In gasoline engines, they are an appealing way to meet ever more stringent fuel-economy standards

“EGR [exhaust gas recirculation] systems now in use on diesel engines were used to meet emissions regulations. In gasoline engines, we think they are an ideal way to meet stricter fuel economy standards,” explained Martin Bauer, Development Director for engine-mounted components at Mahle Behr USA, in an interview with Automotive Engineering.

EGR systems divert some of the engine-out exhaust gas and mix it back into the fresh intake air stream. Mixing exhaust with the intake air lowers combustion temperatures and rates. This improves emissions by reducing the formation of NOx. It also reduces the knock limit, providing better fuel economy through higher compression ratios and/or spark advance.