How to increase side chest dramatically?

I am working out for the last 8 months & really nothing major has improved.
Only my arms have become couple of centimeters thick.
I want to increase my chest, specifically, both sides???
I have used the machines in the most of the gym's to the full/max weight lifting capability.
But now I am just repeating or looping the workout, & don't feel anything is happening in my workouts.
How can I increase my side chest dramatically, what exercises do I need to do ?
Any help appreciated?