What is the engine(s) on the car before 1978 with ensign n177 chassis?
CREATE TABLE "complete_world_championship_formula_one_" (
  "year" real,
  "chassis" text,
  "engine_s" text,
  "tyres" text,
  "points" text
);
SELECT "engine_s" FROM "complete_world_championship_formula_one_" WHERE "chassis"='ensign n177' AND "year"<1978;