Part 2 - 10 Second ZL1

Part 2: tried and true modifications for 10.30s on pump gas

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In the second part of our saga with Redline Motorsports, the crew began tearing down the ZL1 with less than 300 miles on it, just after our track test. The thrust of their efforts would be to utilize the same means of power production, which proved very effective on the CTS-V and other LS based engines. The first and most obvious modification would be increasing the boost, which is done (in this case) with a larger ATI drive pulley and a smaller LPE supercharger pulley. Increasing boost by this method amplifies a restriction in the intake path-the cast aluminum blower snout.

Speaking of restrictions, besides the factory's 9psi of boost, the next most significant component holding back the LSA is its puny 198/216-duration camshaft with a mere .492/.480-inches of lift. Owner Howard Tanner contacted his friend and LS legend Brian Tooley for help spec'ing out a custom camshaft, which he had Comp Cams grind with a 231/248-duration. The cam was matched to Comp 7.400-inch pushrods and Redline's new double valvespring package with Titanium retainers. Last but not least, American Racing 1 7/8-inch long-tube headers (the same as the SS model) were installed with ARH's X-pipe and high-flow cats mated to the factory exhaust system. Before putting it on the dyno, Redline also dropped in a set of Injector Dynamics 98 lb/hr (at 68psi) high impedence injectors and NGK TR6 plugs to provide the appropriate fuel and spark to match.

After a couple of go-rounds on the dyno, Tanner had the fueling and overboost table tweaked to his liking with the timing dialed back for safety. When he finally put the screws to it, the ZL1 belted out a jaw-dropping 654hp on the Land & Sea chassis dyno (that's a 200hp jump from stock) and 624 lb-ft of torque. Before heading back to Palm Beach International Raceway, Redline would have two more tricks up its sleeve. With a scattered rainstorms blowing through town, this gave fabricator Jay Healy plenty of time to whip up a reservoir tank for the heat exchanger. Though the air-to-water intercooler system is much improved from the CTS-V, it still does not have a tank to hold extra fluid. So what is in the system, becoming heat-soaked as you sit in the staging lanes, is all you got…unless you call Redline. This will also give you the chance to dump in some ice for even lower Intake Air Temperatures. But in any car with an automatic trans, a torque converter is easily the best modification to lower elapsed times. So it should come as no surprise that Redline ordered up a 3600-stall unit from Coan for the 6L90E. At the track, these modifications paid dividends with a series of 10-second runs, culminating in a 10.32 at 134mph pass with a 1.54 sixty-foot time. Take that Lingenfelter! [To watch video of the run head to YouTube.com/GMHighTechmag).] Being oh-so-close to the 9-second zone, Tanner vowed to push the ZL1 a little harder in the hopes of becoming the first to hit single digits. But for today, he was just content with being the fastest ZL1 in the land. Not a bad consolation.

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