B'klyn9C1

I thinking of doing a LSx conversion on my 1995 Caprice 9C1 with a 6+ liter Gen 4 motor from a salvage yard. I looking to build a 550 to 650+HP/500+ TQ N/A streetable motor. Assuming I find a engine in relatively good shape where the most it needs a refreshing of the bearings, etc. Do I need to change to a all forged rotating assembly to safely get the numbers I want?

I am familiar with the Gen 2/LT1 stuff where the nodular iron crank, powdered metal connecting rods and hypereutectic pistons can only safely get you around 450HP. Above that most engine builders say spring for a forged rotating assembly and four bolt maincaps. Is that true for a Gen 4 where GM uses the same kind of materials for a Gen 4 rotating assembly???

PS I am also looking to stroke my Gen 4 with a 4" crank for 400+ ci.

rsz288

There is another very recent post somewhere here that puts the limits for stock rods at 950HP. Stock rods tends to point to stock crank as well. So at 550-650 the limitation is really stock cast pistons and the tune. Though unlikely to get to that without a cam that needs notched pistons so the vicious circle begins.