Editing Kylchap (section)

===France===
Chapelon developed the Kylchap exhaust in 1926, and it was tested on [[compound locomotive|compound]] [[4-6-2|"Pacific" locomotives]] of the 4500 and 3500 classes, and a simple expansion Pacific of the 3591 class, producing significant improvements in steaming and in one case a 41% reduction in back-pressure.  However, it first came into prominence in 1929 when applied to compound Pacific No 3566 which combined enlarged steam circuits, increased superheat, feedwater heater, thermic syphon, [[Hugo Lentz|Lentz]] poppet valves with double Kylchap exhaust extractors and chimneys. On a test in November 1929, the indicated horsepower (ihp) output was found to have increased by over 60%, from 1850 ihp to 3000 ihp, while its fuel and water consumption had improved by 25% compared to un-rebuilt engines of the same class. Those results made Chapelon's name and 3566 became well known both within France and in most countries of the Western world.<ref>{{Citation|last=Rogers |first= H.B.C.(Col.)|title=Chapelon - Genius of French Steam |publisher=Ian Allan, London |year=1972 |isbn=0-7110-0281-9}}</ref>