I think what you want to do is have your Wordpress served from nginx on port 80 and set up your node to listen on 1337. Then set up forwarding as per this tutorial.

server {
    listen 80;
    server_name your-domain-name.conf.com;
    location / {
        proxy_set_header   X-Real-IP $remote_addr;
        proxy_set_header   Host      $http_host;
        proxy_pass         http://127.0.0.1:2368;
    }
}

Thanks you very much @asb and @phocks, I finally figured it out !
Thanks to both of your tutorial, I managed to better understand nginx :)

Hi,

I’m in the same situation, but I don’t want to use blog.yourdomain.com for the blog.
I would like to use yourdomain.com/blog

is it possible? (I have the nodejs app in yourdomain.com)