Quote Originally Posted by MaxPF View Post
I heard from a VERY reputable source that the problem with using small port precups on a turbo motor is that the cup will get excessively hot and you will get rapid erosion of the port. I wonder what material the precups are made of. They are simply called "stainless steel", but that covers a wide range of alloys, none of which are the best for a precup IMO. HD IDI's usually use a Nimonic alloy (similar to Inconel)... is that what the cups in the 6.x are that are reffered to "stainless steel", or is it some cheaper alloy...?
The cups are, according to GM, stainless-steel.

I have a disassembled 6.2L engine in the shop that ran for 200,000 miles with a Banks turbo. The cups are no more worse for wear... Peninsular produced turbocharged marine 6.2L diesels from 1984 till 1991. There is no more reputable source than Pen, for info concerning turbocharged 6.2 precup life.

Jim