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Big And Tall: Chevy’s RS-X / ZZ632 Big-Block Cylinder Heads Are Huge

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#1 Bob Riebe

Bob Riebe
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Posted 21 September 2022 - 18:53





While much of the work was already done prior to Dragoiu coming on board for the project, the man who came up with the original design back in the ’80s was a renowned GM engineer. He gets much of the credit since he initially designed the cylinder head and was subsequently brought back in to refine the heads for the ZZ632. 

“Many people have asked if the LS head was an influence on the big-block head, but the story is a little more complicated than that,” says Dragoiu.


Technically, the LS heads were inspired by this big-block head, because the gentlemen who worked on it, Ron Sperry, designed it back in the ’80s. He also had a pretty important hand in the development of the LS engine. — Alin Dragoiu 


In fact, Ron Sperry is the “RS” behind the RS-X. He is also known as the godfather of the LS engine, among many other accolades in a career that spans back to the 1960s. Sperry retired in 2008 but continued to work with GM on a contract basis for special projects until 2020. 

Raise The Roof

Dragoiu explains that he inherited the ZZ632/RS-X project about halfway through, after Sperry fully retired from GM. “The heads were pretty much designed at that point, we were just going into COVID, and Ron retired around that time. I did have some interaction with him regarding the heads. But when I took over, the shape of the intake ports needed a redesign. We tried a few iterations and ultimately ended up with an older design that worked pretty well.”




More Applications

The RS-X/632 was a challenging project, says Dragoiu, because it took the whole engineering team’s experience and know-how to achieve 1,000 naturally-aspirated horsepower on pump gas. The result is that it opens up the heads for many more applications in the future. “The RS-X head is versatile enough to work in a performance or racing application,” says Dragoiu. “Due to the small, compact combustion chamber, higher compression ratios for racing are easily achieved with a piston change.”