EFILive tuning software was used to tune the beast using its unique "Virtual VE Table" function, as the E38 computer uses complex algorithms instead of an actual VE table which we are used to. After starting with the stock tune, 150rpm and ignition timing is added to smooth the idle, and the fuel is trimmed for the bigger injectors. Normally idle parameters wouldn't of had to be modified but the larger camshaft required these changes. Howard made some initial pulls with the 6psi wastegate springs and dialed in the tune. At 9psi, he starts with 12.5 to 14.0 degrees of timing at WOT, which he says is close to APS's tune. Another 3-4 degrees of timing is added from 1600-1800rpm before boost kicks in. Another 2 degrees is added at the upper end by the final tune. Howard says a good rule of thumb is to back off timing at peak torque then ramp back up again. Each pull was data logged with the wideband O2 wired in to make corrections easier. Air/fuel stayed around 11.7 to 12.0 with the final tune, and thankfully there was still some headroom with APS's MAF as it hit only 10,300 Hz. No need for Speed Density just yet.
Logically, the 3psi jump in boost provides a linear increase in power especially from full boost to the over 6500rpm max. As impressive as 654 and 760 peak horsepower sounds, it's not nearly as remarkable as the 600 and 700 ft-lbs of torque available from 3500rpm to 5500rpm. Peak torque numbers were 614 and 730 lb-ft respectively. The incredibly flat torque curve gives a seat-of-the-pants feel comparable to a much more powerful car. The first three gears appear nearly useless with more than a light brush of the throttle. For comparison, a stock ZO6 recently baselined at 450hp and 420 lb-ft on Redline's dyno.
The substantial TiAl wastegates proved steady and reliable, even at 9psi. The increased boost caused only a couple hundred rpm increase in lag, but a much more violent initial hit to the Dyno Dynamics rollers.
Even with a set of M&H 26x12 slicks and skinnies mounted on 16-inch CCW wheels, the turbocharged LS7 still couldn't hold traction on E-town's super-glued launch pad. Almost as soon as boost hit the ZO6 wanted to immediately pitch sideways. One observer stated succinctly, "that car is just evil." After quite a few tries, tire pressure was set at 18psi and Howard walked it out of the hole, making it to the 60-foot in 1.94 seconds. Once he had quite a bit of forward momentum, he was finally able to squeeze into full throttle in second gear. As the result, the 10.68 ET was achieved at 141.3 mph. Most drag racing calculators would attribute that speed worthy of an ET a full second faster. Despite the difficulties hooking, Redline certainly gave us a taste of this kit's awesome potential.
| Sources |
APS Engineering Pty Ltd 73 Merrindale Dr South Croydon VIC 3136 Australia +61 3 9761 7244 www.airpowersystems.com | Redline Motorsports 3223 Guilderland Ave Schenectady, NY 12306 518/355-8460 www.redline-motorsports.net |