In the early-'90s, GM introduced the Second-Generation LT1 small-block. It featured reverse-flow cooling and an aluminum cylinder head with a new port configuration. In essence, the company created the best small-block Chevy cylinder head ever put into mass production. It was released on top of the '92 LT1 Corvette engine and later on the '93 LT1 Camaro. The new port/chamber design that began life as an aluminum casting eventually carried over in a cast iron version. Unfortunately, just as the LT1 concept began its ascension, GM executives decided to put an end to its production. This superstar cylinder head dropped off the performance map because both the aluminum and cast iron heads lacked a coolant crossover passage, rendering them useless to any engine series other than the discontinued LT1.
The LT1 prospered from 1992 to 1996 in various vehicles, but its days were numbered. In 1997, GM released its Third-Generation small-block engine, the LS1. While the new Corvettes and Camaros were about to receive yet another cylinder head breakthrough, the engineers at GM's truck division knew that the LT1 port still had something to offer. Subsequently, the '96 truck-engine series hit the market with the infamous LT1 port in cast iron production. It was called the Vortec design and became the most efficient mass-produced small-block Chevy cylinder head ever created.
When Chevy enthusiasts discovered the capabilities of the Vortec head, they didn't take long to take advantage of the coolant crossover passages and fit them to First-Generation small-blocks. As if building the ultimate OE street-performance head wasn't enough, GM Performance Parts sweetened the deal even further by announcing that each head could be obtained fully assembled for approximately $250.
The cast iron Vortec heads were released in 1996 and produced through 2001. Abetted by a newly redesigned coolant crossover passage, these heads could be bolted directly onto a First-Generation small-block engine with the help of some aftermarket parts. The intake face of a Vortec head is cut at a slightly different angle than the First-Generation SBC heads and features an eight-bolt-hole intake manifold hold down as opposed to the standard 12-bolt design, so a special Vortec intake manifold and gaskets are required to put the Vortec heads on top of a First-Generation small-block. Furthermore, the OE-production Vortec valvetrain requires a self-guided rocker system that will not exceed a maximum valve lift of 0.420 inches unless the valvetrain has been modified.
Now that the history of the Vortec port/chamber design is clear, we can move onto this month's king-of-the-Vortec-head test. We ordered every example on the market in applications featuring 185cc intake runners or smaller; the idea being that a Vortec head is a low-cost street piece and should be tested in a street fashion. Our evaluations would be run across a 0.030-inch-over bore 350ci short-block featuring all remanufactured OE parts that had been balanced and blueprinted by Hye-Tech Performance. Hye-Tech offers this assembly for $900 (less oiling, timing cover/chain, and camshaft), or fully outfitted for a few dollars more.