Although GM has been building and selling crate engines to the general public for years, many of its offerings have hardly been what we'd call "High Performance." Sure, they were good engines. But what they had in quality, they lacked in gusto. Not anymore. GM Performance Part's (GMPP) newest line of crate big blocks is a classic example of racetrack power transcending to the street. We're talking about GMPP's two new big-block Chevy crate engines. Each totaling 572 cubic inches with one for the street and one for the track, or maybe two for the street if you're not against lashing valves and driving around breathing race gas fumes.
The coolest things about either one of these crate engines is that after you've bought one, you don't have to do a thing, that is, except to drop it in your car and fire it up. They come delivered to your door already broken-in with all the necessary fixin's to get you under way. There's very little else you'll need to buy to make these beasts run. Of course, you'll need the standard items like fuel and oil, but you won't have to buy spark plugs or ignition cause it's already in there. Also, both of these engines come with roller cams; a hydraulic roller in the street engine, and a solid roller in the race engine, so there'll be no cam break-in needed either. Both engines even come with their own carb that's already dialed in. Although you may have to adjust it some, depending on where you live and your local weather conditions. But for the money, these things are really hard to beat. And don't think for a minute that these engines are some old rebuilt Rat motors. Every part used in these beasts is 100 percent new and very heavy-duty to boot.
When GMPP set out to build the baddest crate engines around, they sparred no expense ensuring that the engines would live to fight for a long, long time. To that extent, GMPP equipped both big-blocks with 4340 forged steel cranks and rods. Forged aluminum pistons with full-floating wrist pins were also included, 9.6:1 compression for the street motor and 12:1 on the race version. And both engines have roller cams for power and durability. On top of that GMPP installed a new version of its proven rectangle-port aluminum cylinder heads, and then cast up a special single-plane intake manifold to fit the tall-deck Bowtie Sportsman Gen VI block. And to make sure there'd be no chance of any one of these engines not making the power they claim, GMPP installs its own specially made Demon double-pumper carb and a hi-perf HEI complete with wires and AC plugs.
GMPP's new street giant, the...
GMPP's new street giant, the ZZ572/620. 572cid can make a lot of power as we found out.
GMPP full-roller aluminum...
GMPP full-roller aluminum rockers, (1.7:1 ratio) actuate the stainless steel valves while adding horsepower and durability.
Check out how clean the supplied...
Check out how clean the supplied looms keep the GMPP plug wires. All of this comes standard.
A new Bowtie single plane,...
A new Bowtie single plane, tall-deck intake manifold distributes fuel from the 850cfm Demon double-pumper carb, which gets dialed at the factory and shipped right on top of the crate engine.
GMPP even puts the spark plugs...
GMPP even puts the spark plugs in. Check out the healthy D-shaped exhaust port too.
A pair of 2-inch Hooker headers...
A pair of 2-inch Hooker headers mated to 3.5-inch Dynomax Race Magnum mufflers, (neither are included with the crate engine) handled the exhaust duties. Who'd thought you could make so much power with such relatively small headers and mufflers? You might want to think twice about running a 4-inch exhaust on your small-block next time.
Here's all the tuning we had...
Here's all the tuning we had to do to make over 700 hp. The specs called for between 34 and 36 degrees total advance, so we set it at 35 and walked away.
There are some extra bonuses...
There are some extra bonuses that come with buying GMPP's biggest crate engine. The block comes drilled for a remote oil cooler and/or remote filter. Ours came equipped with a new AC oil filter screwed onto the stock location on the left side of the block. The braided line you see is for reading oil pressure on the dyno.
And speaking of oil... GMPP...
And speaking of oil... GMPP ships the engines "dry" and recommends 20W-50 motor oil. The system capacity is 7 quarts.
We like the GEN VI big-block's...
We like the GEN VI big-block's cast timing cover and the built-in pointer it features. This crate motor also came with an SFI-approved Fluidampr harmonic dampener.
Unlike the previous GEN V...
Unlike the previous GEN V blocks, the GEN VI versions feature a fuel pump mounting boss. They also feature the newer-style one-piece rear main seal for no oil leaks. But that means they require a specific oil pan and crank, which GMPP installs.
GMPP'S LITTLE SECRET?
We asked the guys at GM Performance Parts why their engine that's rated to make only 620 hp and 650 lb-ft of torque could crank out 13 percent more horsepower and almost 10 percent more torque on our dyno test? Did they send us a ringer? We demanded an answer!
"The engine is under-rated because we correct the dyno measurements using the SAE (Society of Automotive Engineers) correction factor, rather than the aftermarket standard correction factor." GMPP responded. "Further, we under rate slightly to ensure that a customer can always meet our claimed power numbers if he installs one of our engines on a dyno, no matter which correction factor is used."
POWER TO SPARE
When we bolted this engine onto Westech's Superflow 901 dyno, we were expecting it to make at least as much as GMPP's claimed it would; 620hp and 650lb-ft of torque. What we were not expecting was to eclipse those figures by such a huge amount! Even after GMPP told us the reasons that its engine made so much extra power (see: "GMPP's Little Secret?"), we were still floored. Could this actually be better than its advertisements claim it is? You can bet your checkbook that it is. Because this thing cranked out so much more power, our first thought was that GMPP sent us the race motor instead. But, a quick reality check told us that if it was the race engine, there's no way it would still be running considering we were only feeding it 91-octane pump gas. So we pulled the valve covers to check for valve lash, which there was none. And a quick peek down at the lifter valley confirmed that this engine was running GMPP's hydraulic roller lifters. We guess that with so many cubic inches on tap the right combination of parts can make tons of extra power.
|Dyno Results |
|RPM||Torque ||Power |
|Bore: ||4.560" |
|Stroke: ||4.375" |
|Compression: ||9.6:1 |
|Block: ||GMPP Sportsman tall-deck Bowtie Gen VI, 10.2-inch deck |
|Crank: ||forged 4340 steel, internally balanced |
|Rods: ||6.535-inch 4340 steel, H-beam |
|Pistons: ||4032-T6 forged aluminum w/ floating wrist pin |
|Rings: ||Plasma-moly |
|Cam: ||hydraulic roller, 254/264 duration @ .050, .632 valve lift |
|Heads: ||GMPP aluminum rectangle port, PN12499255, 118 cc chamber, 315cc intake runners |
|Valves: ||stainless 2.25-inch intake, 1.88 stainless exhaust |
|Lifters: ||GMPP hydraulic roller |
|Rockers: ||GMPP aluminum roller 1.7:1 ratio |
|Manifold: ||GMPP single plane |
|Carb: ||850cfm Demon double pumper |
|Ignition: ||GMPP HEI |
|Plugs: ||AC R42XLS |
|Fuel: ||91+ octane required |
|Oil: ||20W-50 recommended, 7-qt. system capacity |
|Valve covers: ||GMPP cast aluminum |
|H2O pump: ||GMPP aluminum |
|Dampener: ||GMPP steel |
|Color: ||What else could it be? Chevy orange |