Name the engine with chassis of maserati 250f and entrant of luigi piotti with year less than 1957
CREATE TABLE "complete_formula_one_world_championship_" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" real
);
SELECT "engine" FROM "complete_formula_one_world_championship_" WHERE "chassis"='maserati 250f' AND "entrant"='luigi piotti' AND "year"<1957;