What happens when you run lean ?

Will running lean just blow holes in pistons, or will there be other damage done ? I'm looking at a GST that has been modded with a SAFC 2. There is a possibility that the previous owner set it too lean.

Burned up rings, melted pistons, scoring of the cylinder walls, warpage of and also I think that can cause pitting of the head. Besides that though, if they were careless enough to run it that lean, what else did the forget about/do to it thats not good? I wouldnt advise getting that unless you are getting a hella good deal.

Lean=detonation=blown motor

So first thing to go would be pistons ?

Yea, well the rings will probably be the first thing to go.

So doing a leak down test should show any damage ? And what pressure should a 6 bolt have on a compression test ?

Yeah, a leakdown test should show you whats up. Compression from 6 bolts when they are new is supposedly like 160, most of them I have seen have been like 130-145.

Perfect timing Thor. I'm just heading out the door to do some tests on her now ! Thanks.

In most cases, speaking from personal experience, the sparkplugs ate it first, and then destroyed the head and turbo. In every single failure I had the corners of the pistons were knock off. There are pics on my site in the AFR/Blown motors section of the Tech Pages to explain this better. Compression was typically around 50-90 psi in these cylinders, for reference.