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2004 Chevy Silverado - Silver Autocross

"Yeah, I want to auto-X the truck..." (Laughter)

John Ulaszek Apr 1, 2005

Step By Step

My '04, pre-mod Silverado. The key to my buildup is the optional ($375) all wheel drive AutoTrac transfer case. The AWD setting sends power to the wheels with traction just like the SS truck. While there is about a 300-pound weight penalty, it allows for phenomenal traction at the drag strip with a relatively narrow all-season tire. An additional benefit is the ability to switch over to 2WD for dyno tuning, slightly better mileage and the occasional burnout.

This view shows just how high a stock Silverado K1500 regular cab is lifted in the rear. While this stance allows for a 9200-pound towing capacity it looks odd in person and detracts from the ultimate handling capability. I focused my suspension efforts on the rear and worked forward.

Right now, the GMHTP faithful are left with precious few options for RWD V-8 performance while we wait for a Camaro replacement. But one of them is an AWD, 325 c.i. V-8 powered, 4.10 geared, four wheel disc brake two seater that can be yours for under 30 grand--if you are willing to get behind the wheel of a truck.

Chevrolet and GMC trucks are available in just about every configuration imaginable, with the exception of the one that seems most obvious to the readers of GMHTP, a Silverado SS regular cab. For the past several years Chevrolet and John Moss have conspired to bait us with the promise of a reasonably priced Regular Cab SS model with the plan of switching us into a stylish but underpowered extended cab model. When I realized the Silverado SS regular cab shown at SEMA last year was just another tease, I decided to take matters into my own hands and headed to the Chevy dealer to option out a regular cab truck that, with a little help from the aftermarket, would satisfy my need for a reasonably priced and performing daily driver. A quick test drive in a Silverado SS provided a baseline for ride, handling, and acceleration. Choosing a regular cab 1500 model narrowed the largest engine option to the 5.3 and transmission to an automatic. Luckily 4.10 gears, AWD transfer case, locking differential, and towing package are available options. As luck would have it, the dealer had a 5.3 AWD truck optioned out perfectly for my little experiment, and after a little haggling I was driving home in a 2004 Silverado for significantly less than the $29,620 sticker price.

After leaving the dealership I arrived at a red light, and I figured it was time to see how badly the 5.3 and 4.10 gears would shred the 245/75-16 tires. The light turned green, I put the hammer down, and then...crickets chirping...nothing. I meekly crawled away from the light, and finally at about 4000 rpm the 5.3 started to show signs of life. It felt good up to the 1-2 shift, where it suddenly fell on its face for a geriatric shift into second gear. After checking the window sticker to confirm I bought a 5.3 not a 4.3, I suspected torque management was the problem. While underwhelmed by the Silverado's performance I knew it had potential, it just needed an attitude adjustment.

In this story I use HP Tuners' VCM software to remove the factory imposed limitations on the 325-inch powerplant, and make a series of systematic changes which I hope will exceed the handling and acceleration of the Silverado SS while matching its excellent ride quality and road manners. While some of my results are subjective I also intend to quantify my results at an autocross course. Many of the modifications are specific to 4x4s or regular cab trucks, but all '99 and up full size Chevy trucks can benefit from some of these mods.

In the next episode I'll install Stainless Works' new full length headers and cat-back and follow up with a wideband dyno tune session using HP Tuners' new wideband interface.


With the stance, alignment, and wheel/tire combo nailed, I felt it was time for some road testing. After about four thousand miles of mixed use I was pleased with the look, but not the handling or ride comfort. Highway driving exhibited very unpleasant characteristics in this combo. Where the truck used to have a very soft disconnected feel on the highway it now acted like it had bad shocks, and on uneven highway pavement it would bob up and down so bad that the CD player would start skipping. Body roll was annoying around town and terrible on highway offramps. Under braking and acceleration the truck would pitch excessively forward or aft. In addition to the handling problems, I still had to contend with Chevrolet's torque management, which was killing wide-open throttle performance and upshifts. While the truck looked good at this point, it had the road manners of a dump truck.

The sway bar installation changed the truck's ride and handling behavior significantly. While potholes would create more cross-car or lateral input, the truck corners extremely flat and consistent, and high-speed stability and resistance to crosswinds are vastly improved. The real test would be at the autocross, after a little convincing the Northern Virginia Corvette Club was willing to let me run the Silverado at one of their sponsored events. The Corvette Club was cautious about letting a truck run as they have seen BMW X5s get up on two wheels. I assured them my truck was different and secretly hoped I was right. On race day I pulled up to the tech line and informed the inspector I "wanted to race the truck", after I convinced him I was serious he teched the truck and sent me on my way. When the time came for my first run an official reminded me that if I got up on two wheels I was done. Not wanting to make an ass of myself I switched on the AWD and eased the truck around the cones for a humble 78.7-second lap.

After I returned to the pits I took a lot of good natured ribbing for not knowing what the vertical pedal on the right was for. I didn't set any records, but I was safe and showed the promoters of the event I respected the opportunity to run a truck. On each subsequent run I picked up the pace, until my final run for a modest 67.3-second lap placed me in the middle of the novice category. The handling in AWD was fairly neutral, with a hint of understeer. I am sure running in 2WD would result in throttle oversteer. By my last lap the doubters were giving me the thumbs up and everyone seemed to enjoy watching the truck.


Hotchkis Performance
Santa Fe Springs, CA 90670
HP Tuners
Buffalo Grove, IL 60089



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