"According to Sean Hyland's book, 4.6-Liter Ford Engines, Teksid of Italy, a supplier to Ferrari, cast those first aluminum blocks. This remains the strongest 4.6 DOHC block available. according to Hyland, these blocks received special treatment. They were cast in SAE 319-modified aluminum alloy, heat treated, and aged for strength.
Beginning in 1999, the Windsor Aluminum Plant (WAP) entered the production picture, producing the 32-valve (DOHC) blocks. Ford beefed up the 4.6 DOHC block, giving it extra ribbing for both strength and quiet operation. The pan rail was also thicker for both strength and reduced noise and vibration. Although the extra ribbing may look impressive, it's there because there is less aluminum in the casting. Keep in mind, this doesn't always make it a better block. The best block to use is the earlier Teksid casting (prior to 1999) if you're going to be doing some serious racing. The Teksid block casting can stand up to 900 hp, according to Hyland. He also says the Windsor aluminum block can take up to 600 hp."
