Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_181892_4 ( year VARCHAR, race_status VARCHAR )

### Question ###
What year(s) was the race status piston?

### Accurate SQL ###

SELECT year FROM table_181892_4 WHERE race_status = "Piston"