Vega Engine
As Bob has stated, the original Vega engine used a very early technology of aluminum block. If I recall correctly, it had a nickle/silicon compound impregnated into the cylinder bores after they were machined, and the aluminum pistons actually had a thin coating of iron to supposedly improve the friction characteristics of the piston/cylinder interface. But the two layers would wear prematurely, and since the cylinder coating was only a few molecules thick, you couldn't just over-bore the cylinder and use oversize pistons. Later engines had cast iron sleeves right from the factory, but they were still poorly designed engines, and badly balanced as well from what I recall.
Now, you might be thinking of the "Iron Duke", which GM brought out after the 2300 Aluminum Vega engine and was put in the Monza and the Monza Wagon (which was actually still a Vega). I believe that these were somewhat more durable, but were badly underpowered. More recently, they made a Quad 4 engine, which was a DOHC design. Better by far, but still lacking the quality of design and manufacture of the Rice Burner DOHC engines. But I believe that they are fairly wide and may not easily fit the Opel engine bay without extensive cutting. Which means you may as well go the route of the 60 degree GM V6 (2.8/3.1/3.4 litre). And be prepared to spend the next year or two making that conversion work.
And Jared, lest I need to remind you, there is no harm in asking advice as to what engine swap would perform best in an Opel, if you don't want to invest the time and effort in building a CIH engine to its ample capabilities. But please be a bit more sensitive to our members when you deride the quality of the cars that they have chosen to spend a bunch of time and money on.
Enough said.
