writer: Randall D. Allen
photographer: Randall D. Allen, Patrick Hill
Last month, we gave you an up-close look at World Products' new LS1X "Warhawk" cylinder heads, then bolted a lightly ported preproduction set onto on a largely stock '02 Z06. To optimize the new heads' performance potential, VMax Motorsports and installer/tuner Real Performance Motorsports (RPM) supplemented them with an intake/exhaust package comprising Kooks headers, a rowdy Comp camshaft, and a FAST intake manifold with a ported LS2 throttle body.
This time around, we'll dyno-test the combo to see how it fares in the area of real-world power generation. Follow along to see if this latest combatant in the LS cylinder-head wars truly lives up to its martial moniker.
On The Dyno
When the Z06 finished shrieking on the chassis dyno, and the final tune was completed, it was clear the C5 had been transformed into a small-cube monster. Maximum rear-wheel horsepower came out to 461.6 at 6,500 rpm, while torque registered 398.5 at 5,400. Clearly, with such an aggressive cam in the smallish LS6, the combination was set up to make big power up top. And since the peak horsepower number came at an owner-mandated rpm limit of 6,500, it's entirely possible that revving the engine 200 rpm higher would have yielded over 470 rwhp.
More important than the peak gains of 115.0 rwhp and 56.5 lb-ft were the improvements recorded over the duration of the pull. On average, the new combo exceeded the stock configuration by 60.3 hp and 53.9 lb-ft. Even more impressive, torque exceeded 370 lb-ft for the entire run. With its broad, flat torque curve and vicious high-rpm pull, this is an engine that should excel in any driving environment, be it on the street or at the track.
"The test was a success, both from a power perspective and, ultimately, for the end user," comments VMax's Pete Incaudo. "World's final product is very similar to what we tested here, with the major difference being the spring/valve package. [Production LS1X heads use Manley units, whereas our test units were equipped with REVs.] As a World Products dealer, we can provide customers with any of the finished World packages or work with them to create a custom package to meet their horsepower goals."
"The transformation from a stock Z06 to a heads/cam configuration was amazing," says car owner Kevin Turner. "Compared with my 500-rwhp '99 Firehawk, the Z06 with the World heads feels very similar in overall power and has tremendous pull through both the midrange and up top. Even with the big cam, the car starts right up, idles fine, and can be driven anywhere without fear. The amount of time that [RPM's] Brian Lohse spent tuning it to achieve the best overall combination of torque, horsepower, and driveability shows."
"The most impressive part of the test was the midrange punch that the engine put out," Lohse says. "Given that the heads are designed for the street, I have no doubt that World or VMax will develop a CNC-porting program capable of making over 500 rwhp on small-cube combinations and exceeding 600 horses on stroker motors. Although more power could have been gener-ated with a slightly leaner air/fuel ratio, the customer requested a tune with an AFR in the mid-11s to keep cylinder temperatures down, in the event he decides to road-race the car."
Overall, our test proved that the LS1X Warhawks are legitimate contenders in the aftermarket LS head market, matching up favorably with some of the best castings currently available. With the recent release of its LS7X heads for big-cube applications, World Products now appears ready to wage battle on all fronts.
Dyno Results
Testing was performed at Real Performance Motorsports in Lewisville, Texas, using a Dynojet Model 248C dyno optioned with a Commander wide-band 02 sensor. Pulls were made between 3,200 and 6,200 rpm for the baseline test and between 3,200 and 6,500 rpm for the follow-up test.