there's a difference about a engine built for n/a purposes or forced induction...take an engine that was designed specifically for forced induction (usually beefier deck support, iron block, heavier rods, pistons, etc.) and try to make it a n/a revver you'll fail without a complete rebuild

just the same as take an engine built for high performance n/a purposes and add forced induction and you over stress the engine b/c its internals, design, and compression characteristics had a much different purpose in mind