Here's a link to a simple time delay circuit which i suppose could be switched by your turbo timer itself (maybe) http://www.hobby-circuits.com/circui...cuit-schematic........ There's also ones which use Time Delay relays so that you can actually adjust the "off" delay but I havent had a proper look for one yet.

Theres also some for sale on fleabay but havent a clue if theyre any good http://www.ebay.com.au/itm/CAR-TIMER...51097956118%26