GM's 1,000 hp 632 cubic-inch crate engine is its largest and most powerful ever

This monstrous motor clocks in at over 10.3 liters of displacement and makes more than 1,000 horsepower on pump gas without a turbo or nitrous.

Kyle Hyatt Former news and features editor
Kyle Hyatt (he/him/his) hails originally from the Pacific Northwest, but has long called Los Angeles home. He's had a lifelong obsession with cars and motorcycles (both old and new).
Kyle Hyatt
2 min read

This 1,004-horsepower monster is the biggest crate engine GM has ever offered.


They say that when it comes to making power and torque, there is no replacement for displacement. While that's slightly less true these days with super-efficient turbocharged engines and EVs, the folks at General Motors are holding fast to that ideology with their latest crate engine, the ZZ632/1000, which clocks in at a whopping 632 cubic inches of displacement and which was announced on Wednesday.

For those of you not accustomed to working in old money, that's 10.36 liters. For comparison's sake, the utterly massive engine only weighed in at 8.4 liters and with two more cylinders. As its somewhat unwieldy name suggests, the 632-cubic-inch crate engine produces a whopping 1,004 naturally aspirated horsepower. It also makes 876 pound-feet of torque, and it does both on 93-octane pump gas.

Apart from its displacement, there are a few notable features that make the ZZ632 special. Chief among these are the aluminum RS-X symmetrical port cylinder heads, which, unlike many previous big block head designs, have identically sized intake and exhaust ports for each cylinder, which helps ensure that all the engine's eight cylinders produce the same power.

The ZZ632 shares its block architecture with GM's only slightly less elephantine ZZ572 crate engine but features a bore that's been increased by 0.040-inch. The engine's stroke has also been lengthened over the ZZ572's by 0.375-inch, which accounts for the bulk of the displacement increase. The engine also features forged steel connecting rods and crankshaft, which helps with engine longevity. GM claims that the ZZ632 withstood 200 simulated dragstrip passes without issue.

Unlike some of its other high-performance crate engine offerings, GM isn't placing a cap on ZZ632 production, and, in even better news for speed freaks, the engines will be kept in stock rather than being built to order. We don't have pricing yet for this monster of an engine, but we suspect it will land somewhere north of the approximately $16,300 that is being charged for the ZZ572.

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