I'm guessing you mean the turbine inlet. It will get as hot as your pyrometer reads if it's held there for a decent amount of time. I'm not sure on a minimum clearance but I'd say around 1.5". If you're that worried you could get it ceramic coated.
My aircleaner paint has blistered being about 4" away from the hot side of the turbo.
I know what did that though, towing a dead truck up a hill. Slow, high load and not much airflow.
If you're worried, a polished metal heatshield will do wonders. Stainless looks great.
FWIW, My truck was painted 8 months ago. Turbo is approx 2 inches from the hood, no insulation. Granted Ive only driven it about a week, but no scorching.
Lee, get it coated. It helps, and isn't that pricey, escpecially on these motors, where you're not spending a lot of dough on all the stuff you buy for gas motors. I'm getting the manifold and outlet housing, as well as the downpipe, coated..
Mostly, my clearances are kind of tight the way I'm doing it, and I want the best fighting chance to beat heat that I can get.
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