SEMA 2021: Air Flow Research Debuts Its CNC Gen-III Hemi Head

When it comes to cylinder head designs, there are few names more iconic than “HEMI.” When Dodge resurrected the Hemi engine for its third generation, everyone expected great things. Mopar actually over-delivered, as there hasn’t been much room for the aftermarket to improve on the factory castings, without making a huge investment in R&D resources.

Air Flow Research has invested those resources and is now releasing its first aftermarket Gen-III Hemi head. In fact, this cylinder head design is so new, the head at the SEMA show is actually a sample casting from the foundry that just arrived prior to the show. “Once we get back from the show, we’re hoping for a two to three month lead time on getting production heads out the door. So the end of quarter-one or early quarter-two,” shares AFR’s Director of Engineering and Technology Chris Sperling.

AFR Gen-III Hemi intake port

The 210cc CNC-machined intake port on AFR’s Gen-III Hemi heads flows an impressive 370cfm at .650-inch of lift. Even in the 180cc as-cast version flow numbers are said to be 50 to 60cfm higher than stock castings.

The new AFR Hemi heads will have two variations. The version on display is the top-of-the-line fully CNC-ported version, with a 210cc intake runner aimed at high-airflow-demand applications, such as forced induction or aggressive naturally aspirated combinations. “We will also be offering a 180cc as-cast-runner version that will be similar to an OE runner size, but will have a CNC’d combustion chamber. Even with similar runner sizes, the as-cast version will flow 50-60cfm over OEM,” says Sperling.

With impressive numbers from the as-cast version, the fully CNC-machined version does even better, with AFR claiming in the neighborhood of 370cfm on the intake at .650-inch of valve lift. Both versions will be offered with springs good to .600-inch of lift and titanium retainers on the CNC’d version, and steel retainers on the as-cast variant, with a titanium upgrade available.

AFR Gen-III Hemi valvespring

Both versions of the heads will be available assembled with improved dual valvesprings and titanium retainers. While titanium will be standard on the fully CNC’d variant, they will be an available upgrade on the as-cast heads.

Due to the design of the Hemi head, maximum lift with stock rocker arms will be in the .625-inch range but larger lift will be attainable with different valve covers and aftermarket rocker arms, which will really allow this new cylinder head from AFR to shine.

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About the author

Greg Acosta

Greg has spent seventeen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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