The common factor between the 2 engines covered by this thread (Sabre and Centaurus) is the Bristol Aeroplane Company Ltd - Aero-engine Department. When the Sabre first entered service it was equipped with sleeve-valves (S-Vs) manufactured and machined by Napier; it was these that were the cause of many of the early S-V failures, even during 2-hr acceptance tests. It was only when help was requested from Bristol, who were by now well-versed in the production of S-Vs for their family of S-V engines, that the problem was solved as Bristol Taurus S-Vs could be adapted for use in the Sabre. Napier's own S-Vs usually lasted 20 to 30 hrs before wear caused excessive oil consumption (hence the 25 hrs TBO I referenced above) whereas Bristol S-Vs lasted 120 hrs without trouble.