mount engine by dynamic name

helpers.load-engine.js

export default Ember.Helper.extend({
  assetLoader: Ember.inject.service(),

  compute([name]) {
    if (this.engineName === name && this._resolved) { return name; }

    this.engineName = name;

    let assetLoader = this.get('assetLoader');
    assetLoader.loadBundle(name)
      .then(() => {
        this._resolved = true;
        this.recompute();
      });

    return null;
  }
});

// usage: {{mount (load-engine boundEngineName)}}

Example by @mike183