Sorry air heads, it's water cooled: http://www.porscheengineering.com/filestore.aspx/Porsche-Engineering-Magazine-02-2014-Le-Mans-%E2%80%93-Battery-Development

Sorry air heads, it's water cooled: http://www.porscheengineering.com/filestore.aspx/Porsche-Engineering-Magazine-02-2014-Le-Mans-%E2%80%93-Battery-Development-for-the-919-Hybrid.pdf?pool=peg&type=download&id=pemagazin-02-2014-artikel-lemans-batterieentwicklungfuerden919hybrid&lang=en&filetype=default&version=3e549e9a-c26c-11e4-a19d-001a64c55f5c http://www.porscheengineering.com/filestore.aspx/Porsche-Eng... (seriously now though - nice document about the 919 hybrid)