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_20440 ( "Engine type" text, "Scenario" text, "SFC in lb/(lbf\u00b7h)" text, "SFC in g/(kN\u00b7s)" text, "Specific impulse (s)" real, "Effective exhaust velocity (m/s)" real )

### Question ###
What is the SFC when the specific impulse is 453?

### Accurate SQL ###

SELECT "SFC in g/(kN\u00b7s)" FROM table_20440 WHERE "Specific impulse (s)" = '453'