Aaron Brzozowski 
If you’ve been praying to the auto racing gods for a way to make over a thousand naturally aspirated horsepower from a factory-original big-block crate motor, Chevrolet has answered your prayers. At the 2021 SEMA Show in Las Vegas, the bowtie brand whipped out its new ZZ632 crate motor – a potent new big-block V8 racing engine available to US customers, with a patently absurd 632 cubic inches of displacement. That’s just a hair over 10.3 liters, if you prefer to think in metric.
The ZZ632 Chevy big-block crate motor was a smash hit at the show, even winning an award for best new product in 2021 in the category of Street Performance products. And now, we finally have a more complete picture of what the ZZ632 will look like when it launches, with new details like its weight and just how it manages to make 1,004 horsepower on 93-octane pump gas without a blower.
Building A Better Big-Block
We’ve covered it already, but a key ingredient in the Chevy ZZ632 recipe is its heads. Even the best cylinder heads for volume production automobiles are cast and subsequently machined – a “quick,” effective process, but one that often results in intake and exhaust ports with slightly different sizes and geometries. Because Chevy has no plans (that we’re aware of) to build 200,000+ of these engines per year and drop them into Equinoxes, the company decided it could spare the time to CNC machine aluminum billet to manufacture the heads. That technique yields outstanding consistency not just between heads, but between ports, so every intake and exhaust port flows gases in exactly the same way, with sizing and geometry carefully selected to maximize flow.
Of course, valves can be a performance bottleneck, too. Generally, you want the largest intake and exhaust poppet valves that you can get away with, but valve mass acts as a limiting factor as the heavier a valve is, generally, the more likely it is to “float” at high RPM. So, Chevrolet selected valves for the ZZ632 crate motor with an enormous amount of surface area, and offset the difference in mass with slender stems. That, plus a super tough, forged and perfectly balanced bottom end, is what allows the ZZ632 crate motor’s unbelievably high 7,000-rpm redline.
Peak power comes in just before redline at 6,600 rpm, and peak torque just a thousand rpm lower than that at 5,600 rpm. Peak sound is available at every rpm.
As for weight, the ZZ632 – like every Chevy big-block V8 before it – is undeniably on the heavy side. It tips the scales at 680 pounds, which is roughly one-and-a-half times the weight of the Chevrolet Corvette’s 6.2-liter LT2 or Ford’s dual-overhead-cam 5.0-liter Coyote V8 as found in the Mustang GT.
The Chevrolet ZZ632 is on pre-sale now at a price of $29,499, but that price won’t be around for long; when it becomes available in earnest, the 1,004-horsepower crate motor will carry a $37,758 price tag.
