Bowtie Heads Vs. Vortec Heads
Bowtie and Vortec (trademarks of GM) cylinder heads are produced by GM's Chevrolet Division. Both have found favor in high-performance applications such as stock car or drag racing and in high-output street driven vehicles. These designs are made available for small and large displacement engines.
The Bowtie trademark is based on the Chevrolet logo and is used for its factory performance aftermarket parts, which aren't available in production vehicles. The Vortec moniker is used in factory-installed applications, and Vortec engines have been mass produced in millions of cars and trucks.
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Bowtie History
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In addition to mass produced high-performance engines and parts, Chevrolet's GMPP introduced the Phase I Bowtie small-block Chevy cylinder head in 1981 for racing applications. Subsequent variations---such as Phase II and 6---were later released, as well as SB2.2 and others, including the big-block engines.
Bowtie Features
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GMPP Bowtie heads feature designs such as increased intake and exhaust port volume and valve sizes, and a chamber shape that promotes better airflow, thereby improving power output in racing applications.
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Vortec History
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The Vortec trademark appeared in the mid-1980s on V6 engines, but the actual Vortec cylinder head design did not appear until 1996 on L31 version GM truck engines. Other versions of the Vortec engine have been produced, but the L31 Vortec head is the only one compatible with earlier block designs. In 2001, Vortec heads were introduced on 8.1-liter big-block truck engines.
Vortec Features
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The sought-after L31 Vortec head is a popular, budget-friendly performance upgrade since it can be used on older engines blocks and because it performs on a level that early GM heads could not achieve without extensive modifications.
The design of the combustion chamber promotes "swirl" (hence, "Vortec") and efficient burning of air and fuel and produces respectable power output. In many cases, mildly modified Vortec heads perform as good as--or better than--the early GMPP Bowtie Phase I or II high-performance heads. Big-block Vortec heads have had limited success in performance applications.
Tip/Warning
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GMPP also offers two additional "Bowtie Vortec" heads with larger ports than the production version. Be aware that--unlike the early Bowtie heads--Vortec cylinder heads require a special intake manifold with the proper bolt pattern.
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