I was using Toyota SC engine for the past few years and I've never install any turbo timer. The Toyota SC is a self-contained unit and no engine oil is flowing through it so turbo timer will be unnecessary.
Turbo timer is only needed on turbocharged engine. The reason, exhaust gas temperatures can reach a very high degree, and during hard driving speed the turbo shaft may reach over 100k rpm. So proper warm up and cool down is essential. To ensure that proper cool down is achieved, that's when turbo timer comes to work. The low rpm idling allows oil to continue to coat the turbo's bearing surfaces and allow them to cool their temperatures to a point below which "coking" occurs. Coking is the primary reason for turbo failure.
Just my lousy 2cents. Hope that helps. :shades_smile: