CREATE TABLE table_name_56 (year INT, power VARCHAR)

When is the earliest year with a Power of 90kw (121hp) @ 4000?
SELECT MIN(year) FROM table_name_56 WHERE power = "90kw (121hp) @ 4000"
SELECT MIN("year") FROM "table_name_56" WHERE "90kw (121hp) @ 4000" = "power"