There is an old adage among the hot rod set that says, "There is no replacement for displacement." In this case, how about 572 cubic inches of displacement of nothing but Bow Tie Rat? Yes, you read that right. GM Performance Parts recently released to the public two different versions of what has affectionately been dubbed the ZZ572 crate engine. First, there is the street engine weighing in at an advertised rated 620 hp and 650 lb-ft of torque SAE (Society of Automotive Engineers) and coming on strong with 9.6:1 compression, perfect for 91-octane Super Unleaded gasoline. The second version of this mother of all crate engines is the full race version with 12.0:1 compression that makes upward of 720 horsepower SAE. The higher-rated hp version is geared exclusively at the racing set, hence its designation as ZZ572/720R (R for race). For both motors, the SAE ratings are conservative and each engine has been dyno-tested by numerous magazines to make way more than their SAE ratings. Our sister publication, Hot Rod, dyno-tested the ZZ572/720R and made 801 hp at 6,300 rpm - not bad for some minor testing, tuning, and carburetor tweaks.
However, it is the ZZ572/620 engine we are much more interested in, primarily because it was intended to be installed into numerous applications, ranging from a replacement musclecar or truck engine to street rods and even marine applications, which is where we intend to use it. An explanation will soon follow as to the validity of this motor as a true marine engine, as well as the actual differences between the 620/720R engines.
Engine Specifications:
The new ZZ572/620 is based around the brand-new Generation VI tall-deck Bow Tie big-block. It is fitted with a forged 4340 steel crank, 4.375-inchstroke, shot-peened, forged 4340 H-beam connecting rods, and 9.6:1 compression, forged aluminum pistons with full floating wristpins. Internally, the hydraulic roller camshaft opens the valves at 254/264 duration at 0.050 inches and closes at 0.632/0.632 inches on the exhaust side. The short-deck is topped with newly redesigned rectangular-port aluminum cylinder heads, where the stainless steel intake valves measure 2.25/1.88 inches on the intake/exhaust side. On top of the dual-wound valvesprings are aluminum 1.7:1 roller rocker arms. Topping the long-block assembly is an aluminum single-plane intake manifold, a 850-cfm Demon carburetor and HEI distributor. Also topping the long-block assembly are very cool, 572 insignia, color-matched valve covers. This engine is so complete and ready to be installed into an older pre-'72 non-emissions controlled truck it's plain sickening. We say truck, because if it were going into a car, the oil pan would have to be changed to accommodate the crossmember of the car's subframe. The engine also includes a flexplate, ignition wires, an oil filter, and a dipstick.
Marine Application:
We have already outlined the GM Performance Parts ZZ572/620 crate engine as the perfect candidate for a replacement truck engine. However, when GM Performance Parts designed the motor, it was done so with the voice of the aftermarket in mind. Numerous components were used from the aftermarket, including pistons, cylinder heads, crankshaft, connecting rods, intake manifold, carburetor, gaskets, and engine bolts.
If you look through the GM Performance Parts catalog, all of the company's engines always state that they are "not intended for marine applications." The reason for this statement is a licensing agreement General Motors has with Mercury Racing, the marine industry's largest engine OEM-equivalent supplier. While the same engine you find under the hood of your new truck is the same engine found under the hatch of your boat, GM has never offered its crate engines for marine applications because of this licensing agreement. However, many performance marine veterans have used GM Performance Parts crate engines for marine usage for years. That licensing agreement officially ended, and while the Vortec engine brand will continue to be the OE supplier of GM- or Vortec-brand engines to Mercury Racing, GM Performance Parts, another entirely different division of General Motors, will begin offering the ZZ572/620 engines for marine usage.
Do you think we're kidding when we say this engine is totally marine-worthy? Other than the fact the engine will have to be externally marinized, which we will explain in a subsequent article, internally, it is ready for severe marine usage. The crankshaft is a severe-duty piece, as are all of the rest of the engines internal components. Even the cylinder head gaskets are Fel-Pro marine head gaskets. So, regardless of whether the ZZ572/620 engine will end up in your classic truck or in your boat, it comes stock with many internal marine accessories, making it a true crossover engine to both markets, automotive and marine.
What Does She Run?
After receiving the engine from GM Performance Parts, we promptly proceeded to have the engine shipped to Whipple Industries in Fresno, California, because we also had much larger plans for the ZZ572/620 engine. Our goal all along was to get a baseline reading of the engine in its purely stock configuration, then swap out the single-plane intake manifold and carburetor for a Whipple Supercharger, with the goal to make at least 800 hp on 91-octane gas.
After arriving at the super-clean and impressive Whipple Industries engine dyno facility, the GM Performance Parts ZZ572 engine was strapped into Whipple's dyno cell. Properly filled with 6 quarts of Valvoline Racing 20/50-weight oil, the engine was fired up and the timing checked to achieve 32 degrees BTDC. We made several initial dyno pulls to check for oil and water leaks, and to properly break in the hydraulic roller camshaft. After warming up the engine for roughly 20 minutes, our first dyno pull was achieved. With zero timing adjustments or carburetor jetting changes, the mighty ZZ572's best pass was 612 hp at 5,500 rpm. However, what the Super Flow dyno chart revealed was an engine whose air/fuel ratios were reading slightly fat at 12.37:1 and should have been somewhere down in the 11.00:1 range, if the carburetor was properly tuned. Since Dustin Whipple knew we were going to eventually replace the single-plane intake manifold and Demon carburetor with an EFI-controlled Whipple Supercharger, he agreed to at least let us make a couple of jetting changes to the Demon carburetor.
Altering the stock jet sizes to smaller ones yielded us the results we were after. The horsepower eventually went up to at least make us hit the GM Performance Parts-rated 620 hp number, and torque was a rather impressive 620 lb-ft at 4,092 rpm.
ZZ572 Part Numbers and Prices
All GM Performance Parts ZZ572 engines are available as both short- and long-block assemblies in either the 620/720 horsepower-rated versions. All short-blocks come with the harmonic balancer, oil pan, and flexplate. The base engines are long-block assemblies with valve covers, but without intake manifolds, carburetors, distributors, carburetors, spark plugs, and wires. The premium engines come completely assembled with all the aforementioned components. Prices on both engines vary but are currently available through any approved GM Performance Parts dealer. We got our pricing from Scoggin-Dickey Performance Center, and we have seen prices lower elsewhere. Do your homework and check around. It will be well worth it. Trust us.
12499190 ZZ572/620 Short-Block $7,995
12498792 ZZ572/620 Base Engine $11,495
12498793 ZZ572/620 Premium Engine $12,995
12498825 ZZ572/720R Short Block $7,925
12498826 ZZ572/720R Base Engine $12,395
12498827 ZZ572/720R Premium Engine $13,995
ZZ572/620
Peak hp: 620 at 5,500 rpm
Peak Torque (lb-ft): 620 at 4,500 rpm
Compression Ratio(advertised): 9.6:1
Carburetor: 850-cfm Speed Demon
Intake Manifold: Single-plane
Camshaft: Hydraulic Roller 0.632/0.632 lift 254/264 dur. at 0.050
Valvesprings: 1.564 diameter 1.800 installed height 197 pds on the seat
Distributor: GMPP HEI
ZZ572/720R
Peak hp: 720 at 6,250 rpm
Peak Torque (lb-ft): 685 at 4,500 rpm
Compression Ratio(advertised): 12.0:1
Carburetor: 1,095-cfm King Demon
Intake Manifold: Single-plane
Camshaft: Mechanical Roller 0.714/0.714 lift 266/274 dur. at 0.050
Valvesprings: 1.567 diameter 2.050 installed height 230 pds on the seat
Distributor: MSD standard