CREATE TABLE table_7679 ("Driver" TEXT, "Entrant" TEXT, "Constructor" TEXT, "Chassis" TEXT, "Engine" TEXT)

What was the Engine, when the Chassis was Bugatti T51, and when the Entrant was a Private Entry?
SELECT "Engine" FROM table_7679 WHERE "Chassis" = 'bugatti t51' AND "Entrant" = 'private entry'
SELECT "Engine" FROM "table_7679" WHERE "Chassis" = 'bugatti t51' AND "Entrant" = 'private entry'