The defence coach wants England to be able to beat the best teams in the world.
Farrell told The Express: "We have to make sure we set the same level as far as intensity, passion and fight but the boys also understand that they have to kick on. To be the best and beat the best, there is an extra 15 to 20% there.
"It doesn't really get any more exciting than the challenge in front of us over the next month. It is about the performances, it is about us kicking on to the next level."
England's first match of the series is against Fiji, followed by games against Australia, New Zealand and South Africa - the world's top three ranked teams.