I've recently started a business making a new type of turbo timer: "Thermal Timer". Started on my 3S-GTE in a st165, and it works well, cooling turbos until their cooled, instead of for a preset time.
check out my site at
www.pampeperformance.com
here's some more info:
The TTA 230 is the first ever Thermal Timer.... aka a Turbo Timer with a temperature sensor. Supplied is a thermocouple which measures the temperature of your turbo housing (where oil is flowing). It is here that temperatures must be low before you turn off your engine, seizing oil flow, and the oil that's left cooks and burns onto the walls. This creates narrowed channels and engine sludge, which then leads to premature turbo failure.
This means that when your engine is hot, the TTA 230 will idle it sufficiently longer. When it's a cold day, it'll see that it's cooling faster than normal, and update the predicted turn-off time.