The engine, as you've no doubt heard, is the 6.2L LSA from the Cadillac CTS-V series, but with forged connecting rods, an improved induction system that flows 30-percent more air and new stainless steel exhaust manifolds. The supercharger and intercooler efficiency is also vastly improved, with the intercooler brick optimized for better flow and improved cooling flow and heat transfer. Anyone who has ever driven a blown car on a road course knows it will typically slow down lap after lap and the engine and supercharger get heat soaked. This should help alleviate that situation, with the upside being improved street performance as well. A dual-mode 2.5-inch exhaust à la Corvette is standard equipment. That means it's quiet around town and has an aggressive bark when you hammer it. (Yank the fuse; it'll be like having straight pipes.)
The end result is 580 hp at 6,000 rpm (an improvement of 24 peak over the CTS-V) and 556 lb-ft of torque at 4,200 rpm. Torque junkies will be happy to know it cranks out over 500 lb-ft from 2,700-6,000 rpm. This makes the portly ZL1 feel hundreds of pounds lighter than it actually is.
Unlike those shopping supercharged Blue Oval products, the ZL1 customer gets his choice of a beefed-up Tremec 6060 manual six-speed gearbox or a 6L90 Hydra-Matic with Tap-Shift function. The 6060 was upgraded with a stronger output shaft, an additional mainshaft roller bearing, a GM-designed short-throw shifter and a refined synchronizer design. All told, it's 30-percent stronger than the similar unit used in the SS. It's mated to a dual-mass flywheel and twin-disc clutch that is wonderfully light in traffic, but robust when it comes to taking abuse.
As for the automatic, it's an impressive piece of hardware. We did a story on the improved Tap-Shift function at superchevy.com (http://www.superchevy.com/features/camaro/sucp_120223_2012_camaro_zl1/index.html), but the long and short is this: This is a three-mode trans. There's what's called "Drive Mode" for everyday ferrying. The trans starts in second gear and behaves like any other slushbox. There's the "Sport Mode," which starts in first gear and holds the trans in gear longer for higher-rpm upshifts. Also, the shift algorithms are more aggressive. The "Tap-Shift" mode is more like a full manual than before. There are no automatic upshifts, even at the redline/rpm limit and the shifts are quicker than those in the SS.
On the track and on the street, both gearboxes worked well. We'd still like to see the gear-changes come quicker and harder in Tap Shift mode, but the fact that Chevy is claiming the automatic ZL1 is actually a tenth quicker in the quarter-mile than the stick makes it awfully tempting. On the other hand, the manual would still be our choice for open track days. It upshifts/downshifts like a dream and felt faster at VIR, though this needs to be borne out through instrumented testing.
Putting The Power Down
It would have been a lot easier for Chevy to just add 154 hp to the Camaro and call it a day, but it could have ended up with an unbalanced beast that would have a propensity for grenading its independent rear suspension. To help the IRS' capability for strip use, the ring gear is beefier than the one used in the SS. The half-shafts in the rear are a different stiffness and diameter to help manage axle hop. This is similar to what is used in the Corvette ZO6. Finally, there's a seven-plate clutch pack in the differential. At the strip and stoplight, the clutch pack helps dissipate energy to put the power down. There's also a diff cooler that knocks fluid temps down 100 degrees F.
To ensure the handling was up to the same level as the horsepower, engineers added Performance Traction Management, Magnetic Ride Control 3.0 and Launch Control for manual transmission versions. Magnetic ride employs valve-less damping and Magneto-Rheological fluid technology to vary the suspension firmness to match the road and driving conditions, according to Chevrolet.