While it's hard to forget the Typhoon and its snarling AWD launches, it's been well over 10 years since GM produced an SUV that would really knock your socks off--a gearhead's SUV. Like many of you, I had all but given up hope of ever driving away from a dealership with a new SUV that could destroy sports cars on the street and at the strip; I could not have been more wrong. Apparently, someone in GM's Performance Division saw the need for a niche SUV that could haul ass and get the kids to soccer practice on time. Enter the Trailblazer SS!
The Trailblazer SS is powered by a nearly identical version of the venerable LS2 small-block found in the C6 Corvette and GTO. Wrestling this mill into the Trailblazer SS really didn't require a tremendous amount of extra engineering since the SSR uses the same powerplant on the same platform, not to mention that a 5.3L resides in the regular V-8 Trailblazer and retains the same physical dimensions. Important changes to the truck version of the LS2 include the use of an electro viscous mechanical fan, a truck-style water pump as well as a taller truck-style intake manifold with a slightly different throttle body. Also in the list of changes is the ever important GMT360 oil pan with a hole running through the pan for the front driveshafts, this looks a little odd when you peek under a two-wheel-drive version and see a large gaping hole in the pan. Even with these changes the Trailblazer SS LS2 still develops an honest 395 horsepower stock (as we'll prove later on the dyno) due in part to some very clever air box engineering as well as the "I can't believe it sounds this good stock" exhaust system.
Mated to the LS2 is the new 4L70E transmission, which makes its first appearance in the Trailblazer SS. The 4L70E is an even further refined version of the 4L60/65E that resides behind everything from trucks to Corvettes. In the AWD version the next link is the Torsen T-3 transfer case which is said to be nearly bulletproof (we'll see), and finally on to the American Axle Manufacturing-produced 9.5-inch rear axle (and front axle on the AWD model) sporting a 4.10 gearset from the factory. While this truck may be heavy, what it gives up in weight it gains back through steep gearing and, in our case, AWD.
Now all of those 395 horses wouldn't be of much use if the truck couldn't effectively handle putting the power to the ground. Here is where personal preference comes in when choosing your preferred driveline. For us it was an easy choice, since the AWD system's extra weight would likely be offset by the traction it provides off the line as modifications progress. Not to mention our locale lends itself to quite a bit of that white crap that falls from the sky every winter and we prefer not to be doing donuts on the Interstate (well, at least not the unintended kind!). Those of you who are blessed to not have the word "snow" in your vocabulary may want to opt for the two-wheel-drive version, which stock can burn the hides with the best of them and would likely edge out the AWD version on the top end.
Helping delegate all this power in the corners is a phenomenal SS-specific suspension setup, which includes beefy upgraded front/rear sway bars as well as Bilstein shocks and an overall 1-inch-lower ride height than the stock Trailblazer. The rolling stock consists of 20-inch polished aluminum clearcoated wheels wrapped in 255/50/R20 Goodyear tires. Bringing it all to a halt from 60 in a scant 115 feet are upgraded 12.8-inch front and standard GMT360 rear vented disc brakes. This whole package was refined and tuned on Germany's famous Nurburgring racetrack.
Our truck is none other than a LT-level AWD coated in a sinister black base/clearcoat. Combined with the not-too-downtown 20-inch wheels, it makes for quite a menacing look that tends to turn heads wherever it goes. This loaded truck (with everything but a rear DVD entertainment package) weighs in at a portly 4,875 pounds with three quarters of a tank of gas. While the SS was relatively quick from the factory, sporting a 13.9-second instrumented quarter-mile (tested with a Passport G-Timer), it wasn't going to kill Corvettes anytime soon.
Driving the SS is a pleasure; the low-profile tires and seemingly stiff suspension are actually quite compliant, even on the pothole-infested streets of Detroit. The brakes are remarkable for an SUV. They pull the truck down to zero from any speed incredibly quick and don't seem to have any fade in heavy street use. Acceleration is brisk, but there is some notable torque management off the line and right before the shifts. The factory calibration is quite good but seems to leave a bit of power on the table. It was obvious that to make any significant power increase, the ECM and TCM would both need to be cracked and tuned to let the truck show its full potential.
Since we couldn't leave anything stock and the torque management was so obvious in this application, it was natural that our first mod would be removing some nanny controls from the ECM and TCM and performing a full dyno tune to optimize spark and fuel on 93 octane. We contacted Vector Motorsports in Ira Township, Michigan, about extracting some power from Trail-Laser and were pleasantly surprised to learn Vector Motorsports tuner Kirk Dearhamer was currently the only person in the country tuning these trucks; with Kirk on board we went to the next step--finding an AWD dyno! Wheel to Wheel Powertrain in Madison Heights, Michigan, set us up with an appointment on its AWD Mustang dyno the next day, and we were set.
When we arrived at Wheel to Wheel, the crew promptly strapped our black beast down to the mammoth dyno. The shop's conditions were relatively optimal considering it was smack dab in the middle of winter; 72-degree ambient temps and 55 percent humidity. Since there are no open tracks within 500 miles of Detroit, we figured it would behoove us to make some simulated quarter-mile runs in addition to traditional dyno runs. This would give us a rough estimate of the truck's abilities, not to mention it would allow us to see the power we gained before and after the shifts as well as the power we picked up after the tune in each individual gear. It didn't take Kirk long to start working his magic, and soon the SS looked like it wanted to jump off the dyno on the launch. We started with a baseline time of 14.4 at 96 mph on the Mustang Dyno, and baseline numbers of 292 horses and 292 ft-lbs of torque. This was done on a heat-soaked engine for tuning purposes. By the time Kirk was done working his magic, the truck had picked up 40 ft-lbs of torque at the launch, 20-plus horsepower and ft-lbs in First and Second gear and an astonishing 40-plus horsepower in Third gear! This dropped our ET to a staggering 13.8 at over 100 mph, and made 309 horses and 320 ft-lbs at the wheels--all this just from a tune!
On the street the SS was basically a whole new truck. It runs like stock until you put your foot into it; but when you do, hold on! The shift points were raised to keep the engine in its powerband and the shifts get firmer based on throttle position. A hard launch no longer results in a "dead" feeling below 3,000 rpm, but on many surfaces it will spin the right front tire! The truck is also an absolute rocket at speed, and passing is a breeze in nearly any gear.
Suffice it to say, we've only just begun to experiment with our new truck, but such incredible gains from tuning alone will be hard to top in the future. Keep your eyes peeled for future breakthrough SS modifications and testing--there's plenty more where this came from!