SELECT SUM("Grid") FROM table_52883 WHERE "Time/Retired" = 'engine' AND "Driver" = 'teo fabi' AND "Laps" < '39'
What is the grid total that had a retired for engine, teo fabi driving, and under 39 laps?
CREATE TABLE table_52883 (
    "Driver" text,
    "Constructor" text,
    "Laps" real,
    "Time/Retired" text,
    "Grid" real
)