Agreed with the above posts. Just so you see where we get these numbers, doomsday....
9 IP/G * 162 G/season = 1458 IP/season (note that this is a rough estimate since some games will only require 8 innings and some will require more than 9)
1458 / 1.10 (the 10% bump) = 1325.45, rounding up in this case to 1326 necessary IP
1326, while being rough, is a good estimate to start with in an OL. Oftentimes, you'll see owners being able to win with < 1300, but until you are comfortable, 1325-ish is a good benchmark. Also, make use of your AAA pitchers to be extra comfy. It's rare that you see a team with under 1250 IP doing well these days, but even down to 1200 is possible if you know what you're doing and feel like micromanaging.