Chevrolet Performance’s ZZ454 crate engine is a formidable package, aimed right at the mid-range of big-block Chevy performance. With a rated 469 horsepower and 519 lb-ft of torque, it is enough out of the box to put the muscle in your muscle car project. While that power level exceeds that of even the legendary LS6 production 454 of 1970, in today’s world of big-cube strokers and extreme performance parts, the bar is certainly higher than it was all those decades ago. Wouldn’t it be nice to be able to raise the ante a few chips when the need might arise?
Exploring the Potential
You might find big-block Chevy crate engines at similar power levels for a lower price, but let’s dig a little deeper into the ZZ engine package. When you are Chevrolet Performance, you really can’t afford to cut corners or skimp, and this 454 is built with the good stuff. For starters, this isn’t a reclaimed, used production block, it is a bulletproof Chevrolet Performance casting with four-bolt mains. Inside, you find all forged internals: crank, rods, and pistons. Built to take punishment while making horsepower, this isn’t a rebuilder’s short-block. Topping the block are a set of aluminum, large oval port cylinder heads featuring compact 110cc chambers, generous 290cc intake ports, and large 2.19/1.88-inch valves. Overall, the package is there to make power and do so reliably.
Set up with a hydraulic roller cam, Chevrolet Performance went with a conservative specification. The crate cam is a smooth runner, with just 211/230-degrees of duration at 0.050 on a 112-degree lobe separation angle, while delivering 0.510/0.540-inch lift. That stick is daily driver friendly. But what if the goal is a nastier “boulevard” idle to impress the boys? This seemed to be the best component change to explore, both for the sound and the potential to make more power.
On the Dyno
We had our new ZZ454 delivered to Westech Performance Group’s dyno facility in Mira Loma, California, for some basic testing. The first job here was to add the components required to get the ZZ454 to run. Our parts list here included a Holley 850-cfm XP double-pumper carburetor (PN 80804BKX), an MSD Pro-Billet distributor (PN 85551), admittedly large 2 1/4-inch dyno headers, and an electric water pump to ease dyno installation. The remainder of the combination was straight out of the crate. After a brief break-in and tuning period we were ready to run for our baseline numbers. The ZZ454 didn’t disappoint, showing peak power numbers of 529.9 lb-ft of torque at 3,800 rpm and 461.3 horsepower at 5,400 rpm.
These numbers are right in line with the advertised figures of 519 lb-ft at 3,700 rpm, and 469 horsepower at 5,500 rpm. Considering testing variation and the use of different test equipment and components, such as the carb and headers, we knew our numbers would be in the ballpark. What was interesting were the rpm points at which the peaks in output occurred. With peak torque at a low 3,800 rpm, we knew the potential was there for plenty more with some minor changes to the combination, starting with that very mild camshaft.
Our first modification was a single part change, replacing the factory Chevrolet Performance camshaft with a hydraulic roller from Comp Cam’s Xtreme Marine line (PN XM284HR). The Comp stick measures 230/236-degrees of duration and 0.547/0.547-inch lift. This cam was selected by Westech’s dyno master Steve Brule for its higher lift and slightly wider lobe separation angle of 112 degrees, in comparison to the cataloged passenger car grinds of similar duration figures. This lobe separation specification matches that of the crate engine’s original cam. The theory behind using the marine grind is improved idle quality with the wider lobe separation for easy cruising, while the added lift generally adds peak power.
Comparing the specifications, the new Comp cam featured a whopping 19 degrees more duration at 0.050-inch on the intake side, with a much more modest increase of 6 degrees at the exhaust. Similarly, the intake lift was increased a meaningful 0.037 inch, while the exhaust gained an insignificant 0.007 inch. So, the specs look impressive, but how about the power? We had the cam swapped in short order and pulled the handle for the results. The new peaks recorded were 530 lb-ft of torque at 3,800 and 493.7 horsepower at 5,800. While the cam swap showed a reasonable gain for a cam swap, we expected the peak torque point to move to a higher rpm, though peak horsepower was now occurring 400 rpm higher on the tach. Our hypothesis here was that the increased cam duration was not being used to its full potential, most likely a result of compromised airflow, with the intake manifold being the most likely restriction. It was a theory we would test further along in our evaluation.
To complement the cam change, our next modification looked toward the valvetrain. The crate engine was equipped with OEM-style ball-pivot rocker arms and stock-replacement style pushrods. Our move here was to improve upon these components with much stiffer Comp hardened pushrods and a set of Ultra Pro Magnum rocker arms. This change not only adds reliability but also provides the capacity to work under higher valvespring loads and deliver a more precise translation of the lifter’s motion to the valves. We installed the new valvetrain and dutifully adjusted the lifters to a minimal preload setting of one-quarter turn past zero lash. We were once again ready to run. Torque moved up measurably to 535.7 lb-ft at 3,800-3,900 rpm, while horsepower was again the bigger winner, now recording 503.8 horsepower at 5,900 rpm.
Having gained 42.5 horsepower and a handful of lb-ft of torque with a cam and valvetrain change, we were pleased with the results so far. By showing restraint in selecting a moderate cam, the 454 still exhibited a clean idle that is really street friendly, while presenting a more noticeable bark at idle. With 13.5 in-hg of vacuum at idle, we had more than enough for power brakes, and wouldn’t expect a need to two-foot an automatic transmission at the stop lights. Best of all, we could just picture the street jaw-boning, and the pride of saying there is 500+ horsepower under the hood. That comes with a whole lot more street cred than a four-handle number. What’s next for our 454? We’re going to be looking for a seven-handle power number from the same basic combination, opening the bottle on nitrous.
1. Our test engine is a Chevrolet Performance ZZ454 (PN 19331574), rated at 469 horsepower and 519 lb-ft of torque.
2. Prior to baseline testing, several key components are needed to have a running engine. The crate engine comes sans carburetor, so we added a Holley 850-cfm XP double-pumper.
3. Likewise, the crate does not include a distributor. We used an MSD Pro-Billet distributor (PN 85551) which plugged right into the dyno’s MSD Digital 7 programmable ignition system.
4. The ZZ454 is equipped with Chevrolet Performance cylinder heads (PN 12363396), which feature large oval intake ports at 290cc, and large 2.19/1.88-inch valves. Chambers are 110cc.
5. To handle the exhaust chores for testing purposes, we bolted on a set of custom dyno headers that featured large 2 1/4-inch primary tubes. The front dress on the ZZ454 crate engine includes a crank damper and a mechanical water pump. For duty on the dyno the water pump was exchanged for a CSR electric unit for ease of installation and to eliminate the need for belts and pulleys.
6. In its out of the box form, dressed as described, the engine delivered more than its rated torque, with 529.9 lb-ft recorded, while power was down a few ponies at 461.3. Interestingly, the rpm points of our peaks were very close to the rated engine speeds.
7. Our first modification would revolve around replacing the very mild original cam. In order to remove the timing cover, the oil pan must be loosened to allow it to drop.
8. In order to swap the cam, the intake manifold and valve covers need to come off, and then the valvetrain, including the rockers, pushrods and lifters, are removed. The ZZ454 uses an OEM production style lifter arrangement, which retains the lifters via a set of dog-bones for lifter alignment and a retention spider that bolts down in the lifter valley.
9. With the valvetrain clear at the top and the front cover and timing set removed, we extracted the factory cam. The specifications for the stocker are 211/230-degress duration at 0.050-inch, 0.510/0.540-inch lift, and a 112-degree lobe separation angle.
10. Our replacement cam is a Competition Cams catalog grind, the Xtreme Marine XM284HR. Specs here are 230/236-degrees duration at 0.050, 0.547/0.547-inch lift, and a 112-degree lobe separation angle.
11. The ZZ454 features the MkVI cam retention system, which utilizes a thrust plate to control the fore and aft motion of the cam. This requires a matching camshaft style with a stepped nose.
12. We reinstalled the valvetrain, including the original ball-stud pivot OEM-style rocker arms, setting the lifter preload at just one-quarter turn past zero lash. The camshaft was the only part changed at this stage.
13. With nothing other than the cam change, power was clearly improved with a peak of 493.7 horsepower now occurring at 5,800 rpm. The cam extended the useable rev range of the engine by some 400 rpm.
14. Our next modification sought to get the most from our cam change via an upgrade of the stock-style valvetrain. The Comp hardened pushrods can handle greatly increased load and rpm compared to the stockers.
15. Comp’s Ultra Pro Magnum rockers are bulletproof thanks to the steel body, but designed to minimize dynamic inertia. They feature a top quality roller trunnion and tip.
16. Westech’s Steve Brule adjusted the Comp rockers to the same minimal preload setting of one-quarter turn past zero lash.
17. The taller aftermarket valvetrain wouldn’t clear the ZZ454’s original valve covers. The solution was to borrow this racy fabricated-aluminum set from another engine. The valvetrain improvement showed a significant gain in power, with horsepower now solidly above the 500 mark, registering a peak of 503.8 hp at 5,900 rpm. Now that we have the base engine working to its potential it’s time try out some power-adders. But that’s another story for another day.
SuperFlow 902 Engine Dyno
Tested at Westech Performance Group
Photography by Steven Rupp, Steve Dulcich