Portfolio grind links open on a external blank window, how?

Hi…
sorry but I searched on the forum but didn’t fin a solution for my situation.

I have made a grind portfolio with portfolio elements made by an image+title and a external link. The portfolio grind element is set open in a new page but the portfolio won’t open in a blank page…
How I can do this?

http://www.caisersouze.com/wp_works/portfolio-example/
I wish to open my custom link on a new blank page, here it opens at themeforest for example, but on the same page.

Thanks for your help.

Caiser