The Heroku router will timeout all requests at 30 seconds. You cannot reconfigure this.
See https://devcenter.heroku.com/articles/request-timeout
It is considered a good idea to set the application level timeouts to a lower value than the hard 30 second limit so that you don't leave dynos processing requests that the router has already timed out.
If you have requests that are regularly taking longer than 30 seconds you may need to push some of the work involved onto a background worker process.