Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_181892_4 (year VARCHAR, race_status VARCHAR)
### Question:
What year(s) was the race status piston?
### Answer:
SELECT year FROM table_181892_4 WHERE race_status = "Piston"