I'm in the process of building up an IAG stage 1 short block (forged pistons, upgraded bearings, balanced/blueprinted) for my LGT, along with ARP head studs and STI cams in my original heads, which I had rebuilt.
The LGT uses a different upper oil pan, as mentioned earlier. However, I was surprised to discover that two of the four forward mounting holes don't line up, and the block casting is slightly different to account for those hole locations. Also, other models use m6 bolts to mount the oil pan; ours has four m8 bolts at the front, I'm assuming for the engine mount load path. I had to drill and tap two holes in my shiny new block. :-( I filled the two unused holes with JB weld to minimize stress risers.
There's not enough metal to tap all four for m8 bolts. I tapped two mounting holes for m8 and actually used studs instead of bolts, installed with red loctite. Unfortunately I had to use m6 bolts for the other two locations. In the end, I'm comfortable with the load path but imagine I could have problems with a really stiff or solid front engine mount.
Hope that made sense. Just a heads up for others who try to use a non-LGT block. I'm sure this has been mentioned elsewhere, but I didn't see it.
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