I have installed three engines: events, blogs, and site search. When I've installed events engine, a compiled file was created under root/vendors/extensions/events. However, I can't find these folders for blogs and site search.
Following is my gem files:
* actionmailer (3.2.16)
* actionpack (3.2.16)
* activemodel (3.2.16)
* activerecord (3.2.16)
* activeresource (3.2.16)
* activesupport (3.2.16)
* acts-as-taggable-on (2.4.1)
* acts_as_indexed (0.8.3)
* arel (3.0.3)
* awesome_nested_set (2.1.6)
* babosa (0.3.11)
* bcrypt-ruby (3.1.2)
* builder (3.0.4)
* bundler (1.3.5)
* coffee-rails (3.2.2)
* coffee-script (2.2.0)
* coffee-script-source (1.6.3)
* decorators (1.0.3)
* devise (2.2.8)
* dragonfly (0.9.15)
* erubis (2.7.0)
* execjs (2.0.2)
* filters_spam (0.3)
* friendly_id (4.0.10.1)
* globalize (3.0.2)
* hike (1.2.3)
* i18n (0.6.9)
* journey (1.0.4)
* jquery-rails (2.3.0)
* json (1.8.1)
* mail (2.5.4)
* mime-types (1.25.1)
* multi_json (1.8.2)
* orm_adapter (0.5.0)
* paper_trail (2.7.2)
* polyglot (0.3.3)
* rack (1.4.5)
* rack-cache (1.2)
* rack-ssl (1.3.3)
* rack-test (0.6.2)
* rails (3.2.16)
* rails-i18n (0.7.4)
* rails_autolink (1.0.9)
* railties (3.2.16)
* rake (10.1.0)
* rdoc (3.12.2)
* refinerycms (2.1.1)
* refinerycms-acts-as-indexed (1.0.0)
* refinerycms-authentication (2.1.1)
* refinerycms-blog (2.1.0)
* refinerycms-core (2.1.1)
* refinerycms-dashboard (2.1.1)
* refinerycms-events (1.0)
* refinerycms-i18n (2.1.0)
* refinerycms-images (2.1.1)
* refinerycms-pages (2.1.1)
* refinerycms-resources (2.1.1)
* refinerycms-search (2.1.0)
* refinerycms-settings (2.1.1)
* routing-filter (0.3.1)
* sass (3.2.12)
* sass-rails (3.2.6)
* seo_meta (1.4.0)
* sprockets (2.2.2)
* sqlite3 (1.3.8)
* thor (0.18.1)
* tilt (1.4.1)
* treetop (1.4.15)
* truncate_html (0.9.2)
* tzinfo (0.3.38)
* uglifier (2.3.2)
* warden (1.2.3)
* will_paginate (3.0.5)
Most likely, they're tucked away in the gem's own directory, the location of which depends on your OS and ruby management system you're using (rbenv, rvm, etc.)