The 2.1-liter, 600hp turbo four-cylinder in the Ford Mustang GTP was considered seriously high-tech in 1984. According to Dave Dellinger, who worked on the car, "The shop rumor was the iron block was an Aussie-sourced 2.3-liter production block. The deck was solid (welded?), and the water was diverted out of holes machined in the outside of the cylinders into a fabricated manifold that then attached to the radiator. The head was a four-valve DOHC, and was intended to someday be a bolt-on kit for the SVO Mustangs and Turbo Thunderbirds. The head also had an external water manifold. But the head castings were porous and would often crack around the valve-spring seats. The block used a billet aluminum girdle to retain the crankshaft as a production block would use separate main bearing caps. Being dry-sump, it had a shallow cast aluminum oil pan with 12 ports for oil scavenging.... BTW, under dyno conditions and more boost, the 600hp figure is VERY conservative."