When I purchase my Fiero the original swap had been with a Series I 3800 SC from a Buick and they toasted the engine (incorrect coolant fill and actually believed the temp gauge).
Engine was swapped with a series I with a NA 92 Pontiac Bonneville. Supposedly it was beefed up during the rebuild, whatever that may mean. The engine runs good and strong but since there is little or nothing out there for pumping up the Series I 3800, considering adding the SC back in, as I have the SC and associated hardware that came with the car. Looking for some opinions on if it would actually be worth it or not. Primarily considering it as the cost would be negligible, since I have most of the components needed.

From my research, it appears the heads and engine are basically the same between the NA and SC (Correct me if I'm wrong), though assuming there would be a compression difference. I installed a new control chip as the car still had the original SC chip when I purchased it, so I could swap that back easily enough. Alternator would have to move as the NA is mounted up top, but shouldn't be a biggee. I would assume I would need to play with the SC pulley size to keep the boost lower to prevent popping head gaskets.

I sure someone somewhere has done this in the past but not pulling up much other than for series II/III when I try to search. Any input is appreciated.

I was investigating something similar last week. I have a series 1 L67 that seized on me, and was having a hard time finding a replacement, so researched using a NA block. The main differences internally is the NA is a higher compression ratio, and the rods are not as strong as the L67 rods. That being said, it has been done a few times. The expectation was that it would hold up for a while, but eventually it might take out a rod.

I now have two '95 blocks I'm working with, and will have a spare set of rods ( and pistons) from a 92K motor, if you think you might want to go that far.

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'87 GT in process, including GA / Seville brakes, Poly Suspension, '95 3800 Series 1 SC ( 225 hp ) 4t60e.

Yeah, I figured the SC engines probably had forged crank/rods. I was thinking just running a smaller pulley with maybe 5 lbs of boost range. The engine runs great and has a fairly fresh rebuild, so hate to blow it just jacking around. I think I will leave well enough alone and just keep an eye out for a later model SC engine and stash it for replacement when this one goes. I have another clean cradle I could work with.

Thanks!

The NA engines have weaker and Different PISTONS and RODS. In the SC version, the rods are "shorter", the piston" Pin" placement is different, and they are Both "Forged". the only thing the Same is the Block and the Crank. probably some other "not so noticeable" changes.