Kyösti Kylälä (born Gustaf Georg Adrian Byström; 16 August 1868 in Salmi – 15 August 1936 in Vyborg) was a Finnish railroad engineer and self-taught inventor. In 1919 he patented in the UK an 'Improved means for increasing the draught in steam boilers, especially on locomotives.' Later the French engineer André Chapelon, developed and improved the invention by using a second-stage nozzle and adopted the name Kylchap for this design. Kylchap exhausts are found on many French and British locomotives notably the Flying Scotsman and the world record holding Mallard.