Specialty File
Traction is a huge concern every time horsepower guru John Lingenfelter drops by with a hopped-up car. For one thing, he knows we don't allow drag-racing slicks. Instead, we insist on running all our tests on less-sticky street rubber, which makes the art of launching 500-hp Corvettes very much like performing an intricate tap dance when it comes to getting the throttle and clutch to work together just right. And even with a perfect launch, the tires can't handle a full-on throttle until about 30 mph, which means that although horsepower ultimately determines acceleration times, traction does indeed play a big role.
Lingenfelter is concerned enough about his cars' getting the kind of traction that will support his performance claims that he sometimes brings a broom and dutifully sweeps the launch area before every run.
This time, no broom or worries about traction were necessary because Lingenfelter's most recent creation--a modified GMC Sierra C3 pickup truck--had the advantage of full-time four-wheel drive. You read that right: Lingenfelter's latest is a truck, and it's not the first modified beast of burden we've tested from the man responsible for the quickest Chevy Corvettes and Dodge Vipers we've ever driven.
In fact, the Lingenfelter Sierra C3 is the third Lingenfelter Performance Engineering (LPE) behemoth we've sampled, but it is the first to have the benefit of a full-time, four-wheel-drive drivetrain. Thanks to the four-wheel-drive model's inherent traction and four-speed automatic, perfect launches are a cinch even for flunkies from the Jerry Lewis School of Tap Dancing.
The C3, however, is not the only available Lingenfelter-tuned truck. Also on offer are a line of products and services for any V-8 equipped GM pickup. Among the most noteworthy is the Eaton Roots-type supercharger system from Magnacharger. Bolted onto any of GM's truck V-8s, this setup pumps 6.0 psi of air into the engine, adding about 60 more horses.
Our C3 started life with the standard 325-hp, 6.0-liter V-8, and before the Magnacharger system was bolted on, Lingenfelter performed a host of engine mods aimed at increasing airflow. It's all part of the 6.0L SC package, which goes for $14,500. That price includes installation, but shipping to Lingenfelter's shop in Decatur, Indiana, is extra.
First, the motor is completely stripped down. New forged aluminum pistons maintain the stock compression ratio but are stronger. The original connecting rods and crankshaft are then precision balanced. Next, to increase engine breathing, the aluminum heads get a careful porting and polishing, new stronger and larger stainless-steel valves replace the stock steel ones, and heavier valve springs are installed. In addition, a new camshaft opens the valves higher and longer to flow more air. A three-angle valve job contours the back of the valve and the valve seat to further enhance airflow.
Those mods plus the blower up the horsepower to 475--150 more than stock. Torque jumps from 370 pound-feet at 4000 rpm to 500 at 4000 rpm. To handle the extra juice, the hydraulic line pressure in the transmission is increased to clamp the clutch packs harder so they won't slip. A new torque converter permits the engine to rev 500 rpm higher during a brake-torque launch, which improves off-the-line oomph.
GMC C3s are amazingly quick for their girth, but the LPE mods bring the two-and-a-half-ton beast down to Corvettelike acceleration. The 60-mph sprint goes from 7.8 seconds in the stock GMC to 4.7--matching the quickest stock non-Z06 Vette we've ever tested. And 100 mph whooshes by in only 12.7 seconds--10.7 seconds sooner than a stock C3, just a shade slower than the last non-Z06 Corvette we tested, a 1998 model that performed the feat in 11.0 seconds ( C/D, August 1998). The LPE C3 also nearly equals that Vette's quarter-mile pass with a 13.3-second run at 102 mph vs. 13.1 seconds at 111 for the Vette. Top speed is still artificially governed, but LPE ups the governor to 130 mph from the stock's 108.
Perhaps most impressive is the C3's neck-snapping throttle response. Cruise at 30 mph, floor the throttle, and bang! 50 mph flies by in only 2.4 seconds--a hair slower than the $119,219 Porsche 911 Turbo Tiptronic S--the fastest showroom automatic we've tested--which does it in 2.3 seconds ( C/D, March). GM's excellent four-speed automatic transmission works unobtrusively, and as the test results indicate, it's always willing to drop a gear or two when the pedal's thrown down.
Although our C3 tester wasn't cheap with a $53,525 as-tested price, the fun that could be had knocking off plenty of high-dollar sportsters-- with a pickup truck!--at stoplights perhaps makes that price seem justified. One thing's for sure: You won't flub the starts.
Lingenfelter Performance Engineering, 1557 Winchester Road, Decatur, Indiana 46733; 219-724-2552; www.lingenfelter.com.
