The strongest Duke is the Mercruiser, Volvo Penta, OMC 3.0l engine. It pumps out a reliable 140hp. The possible problems with putting it in a Fiero are bellhousing bolt pattern, engine mount location, and it comes with non cross flow heads. You could probably use a v8 adapter plate for the bell housing, motor mounts could be fabricated, and I believe the cross flow heads are a bolt on. You would lose some flow with the cross flow heads unless you want with SD heads. The Merc heads are SD cast iron non-crossflow.

As for strong auto applications, I wish I knew. It is rumored that s-10 blocks are stronger than the typical Fiero block. I would like to examine several different types and years of Duke componets to find out which are better. GM had a habit of continuously removing material from parts to make them lighter and cheaper. Your best bet for a strong Fiero block that will bolt in is an early eighties FWD car. Try looking at Chevy Citation and Celebrity blocks. I had an '80 Citation that did not want to quit. I ran the snot out of that thing. It finaly blew a head gasket when my father tried to run 80 with no water pump belt.

If anyone has more info on factory Duke parts let me know.

Erik-