SELECT "engine" FROM table_204_864 GROUP BY "engine" HAVING COUNT("team") >= 3
tell me an engine that was used by at least 3 different teams .
CREATE TABLE table_204_864 (
    id number,
    "pos" number,
    "class" text,
    "no" number,
    "team" text,
    "drivers" text,
    "chassis" text,
    "engine" text
)