In　view　of　low　thermal　efficiency　of　IC　engines,　two　additives,　M1　and　M2　were　added　to　the　gasoline　at　the　volume　fractions　of　1‰　and　2‰　respectively.　The　effects　of　the　additives　on　engine　brake　specific　fuel　consumption　(BSFC),　cylinder　pressure,　instantaneous　mass　fraction　burned　(MFB)　and　emissions　were　investigated　on　the　test　bench.　The　experimental　results　indicate　that　the　average　BSFC　is　reduced　with　the　additives　adding　to　the　fuel,　the　BSFC　is　reduced　by　3.41%　when　adding　1‰　M1.　The　M1　gives　more　BSFC　reduction　compared　with　the　M2.　But　the　engine　is　subject　to　knocking　in　high　load　range　when　adding　M1　more　than　2‰.　The　peak　cylinder　pressure　rises　and　the　timing　of　the　peak　cylinder　pressure　and　the　maximum　instantaneous　MFB　advance　using　M1-added　fuel　than　using　the　base　fuel.　While　adding　both　M1　and　M2,　the　CO　and　HC　emissions　reduce　in　low　and　mid　load　range,　but　NOx　emission　slightly　rises.