There were at least 2 different drivers and 5 engines total. Fura Fura had 3 engines which all only lasted 1 race and there were 2 other engines which only lasted 2 races.

Regarding Sirio. Its possible that the engines in South America where all Mk1. They were reknowned for having serious problems and not lasting any length of time. Sirio denied anything wrong with the engines. But the conrod was so obviously weak.

Its quite possible you got one of the Mk2 engines which mysteriously are far improved and dont have the same reliability problem relating to the conrod.