Alternative　fuels　have　become　the　new　energy　for　future　life.　Compared　with　others,　Dimethyl　ether　(DME)　is　regarded　as　one　of　the　most　promising　choices　for　future　internal　combustion　(IC)　engines.　Due　to　some　negative　properties　of　ethanol,　spark-ignited　(SI)　ethanol　engines　always　encounter　some　barriers　such　as　the　high　fuel　consumption,　low　power　output,　and　difficulty　in　cold　start.　In　order　to　deal　with　the　above　problems,　the　SI　ethanol　engine　is　enriched　with　DME　aiming　at　improving　the　overall　performance.　Under　the　engine　speed　of　1400　rpm,　three　DME　volume　fractions　of　0-2%　and　various　intake　manifold　absolute　pressures　from　43.4　kPa　to　81.0　kPa,　the　influence　of　DME　addition　on　the　performance　of　SI　engines　at　the　stoichiometric　air/fuel　ratio　were　experimentally　investigated　in　this　paper.　The　intake　and　exhaust　manifolds　were　modified　to　ensure　the　injection　of　ethanol　and　DME　as　well　as　collect　the　exhaust　emissions.　The　results　indicate　that,　DME　addition　avails　increasing　the　engine　indicated　thermal　efficiency　by　about　15%.　And　DME　addition　benefits　reducing　the　combustion　duration　due　to　the　elevated　flame　speed　of　mixtures,　especially　at　mid-to-high　loads.　Besides,　the　DME　blending　is　also　capable　of　reducing　HC　emissions　under　the　test　conditions.　The　HC　emissions　of　the　DME/ethanol　engine　are　decreased　by　35%,　compared　with　those　of　the　original　ethanol　fueled　engine.　Thus,　under　the　tested　operating　conditions,　DME　enhancement　can　be　used　to　enhance　the　fuel　economy　and　reduce　parts　of　the　exhaust　emissions　for　SI　ethanol　engines.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.