With the free-flow Gibson...
With the free-flow Gibson shorty headers and after-cat exhaust system, Hypertech Power Programmer Plus and PowerStat thermostat, and free-flow K&N air filter, our trucks quarter-mile times improved to 17.20 seconds at 79.90 mph from the stock baseline time of 18.05 seconds at 75.81 mph (uncorrected). Thats an 8/10-second improvement over the baseline numbers.
The improvement in our trap...
The improvement in our trap speeds comes mainly from the Gibson 14-gauge, mandrel-bent shorty headers. Each kit contains bolt-on products requiring only basic handtools. No cutting or welding is required for installation.
Compare the configuration...
Compare the configuration of the stock exhaust manifolds with the free-flowing Gibson headers, and you can see why you&8217d want to upgrade the stock exhaust system. The Gibson nonrestrictive exhaust headers help dispense the spent exhaust gases faster and better and weigh nearly 10 pounds less than the restrictive, cast-iron stock manifolds.
The remainder of the exhaust...
The remainder of the exhaust system consists of heavy-duty stainless steel 3-inch mandrel-bent tubing and a Gibson muffler that&8217s baffled and chambered to produce a quiet but throaty rumble.
Once the stock cast-iron exhaust...
Once the stock cast-iron exhaust manifolds have been removed, the Gibson installer, Erik Silvey, uses tape to hold the new exhaust gasket to the Gibson header as he&8217s positioning it. He even applies Permatex Ultra Copper High-Temp Gasket Maker to ensure that there will be no leaks around the exhaust ports.
Silvey then installs the Gibson...
Silvey then installs the Gibson header and removes the tape, holding the header gasket to the flange. He installs all the provided header bolts handtight and then torques them to the manufacturer&8217s recommended 25 lb-ft. The truck is then lifted up so he can reconnect the collector flange to the stock exhaust pipe.
He unbolts the stock head...
He unbolts the stock head pipe after unbolting the catalytic converter. To facilitate removal of the muffler and stock tailpipe, Silvey opts to cut the old pipe with a hacksaw.
Once the cutting is complete,...
Once the cutting is complete, Silvey removes the stock rubber support bracket that holds the muffler and tailpipe to the truck&8217s frame and drops out the stock muffler and head pipe from under the truck. The new Gibson stainless steel tubing has all the stock posts to reconnect to the factory rubber supports. Re-using the stock rubber support brackets gives the exhaust system room for growth because when it gets hot, the entire exhaust system expands and gets longer.
Silvey bolts the new Gibson...
Silvey bolts the new Gibson mandrel-bent head pipe to the stock exhaust after-cat flange. He attaches the new free-flow Gibson stainless steel muffler to the new head pipe. The muffler is a simple slip-fit application.
Silvey fits the new muffler...
Silvey fits the new muffler to the tailpipe and secures it using the provided U-shaped muffler clamps. He applies the proper torque to each bolt.
Silvey then adds the stainless...
Silvey then adds the stainless steel exhaust tip, which won&8217t discolor due to the unique intercooling effect Gibson has designed into all its muffler tips. Once everything has been installed, Silvey fires up the engine to check for any exhaust leaks. After the headers have warmed up, Silvey retightens all the connections in the exhaust system.
We also installed the new...
We also installed the new Hypertech Power Programmer Plus and PowerStat thermostat. The Power Programmer Plus interfaces with the truck&8217s OBD-II computer system. The PowerStat thermostat, rated at 160 degrees, allows peak performance from the engine while keeping the truck running cool.
Installing the PowerStat thermostat...
Installing the PowerStat thermostat is a simple remove-and-replace procedure. Silvey drains the radiator coolant to below the engine&8217s thermostat and removes the thermostat housing. The stock 195-degree thermostat is replaced with the Hypertech PowerStat unit rated at 160 degrees. The stock housing includes a rubber O-ring which ensures a tight seal, so a silicone sealer on the housing is not needed for retightening the stock bolts.
To install the Hypertech Power...
To install the Hypertech Power Programmer Plus, hook one end of the Programmer Plus into the Data Link Connector (DLC). Once the system is hooked up, follow the very detailed instructions provided by Hypertech. The Power Programmer Plus simply asks a series of questions about the truck, and you answer them by pushing either the Yes (Y) or No (N) button. It couldn&8217t be easier.
In the previous installment of Project Daily Driver, we saw our new three-door 1996 Chevy 1/2-ton undergo a suspension transformation from stock to ground-hugger. Once we had the truck down to a more respectable ride height with all Bell Tech lowering components, our attention turned from the suspension to squeezing some extra ponies out of the stock but all-new-for-1996 Vortec 5000 engine.
Our 5.0L V-8 engine is by no means a slug in stock form. According to the manufacturer, the Vortec 5000 V-8 produces 230 hp at 4,600 rpm and 285 lb-ft of torque at 2,800 rpm. Compare those numbers to the same 5.0L-equipped truck in 1995. The 1995 5.0L engine produced a mere 175 hp at 4,200 rpm and 256 lb-ft of torque at 2,800 rpm. The 1996 Vortec 5000 engine even beat the venerable 1995 5.7L 350ci small-block, which produced 200 hp at 4,000 rpm and only slightly better torque figures of 310 lb-ft. However, being in the magazine business means modifications, and that’s exactly what we decided to do.
On-Board Diagnostics (OBD-II) is another brand-new-for-1996 feature. Even before it was announced that this new electronic system would be standard on all 1996 vehicles, the general population as well as the aftermarket industry was already wondering what kind of engine modifications could be made to OBD-II-equipped trucks. For more information and a really in-depth look at OBD-II, see "OBD-II & You," Sept. 1996.
Next time, we'll turn our lowered truck into the quintessential sport truck with numerous body bolt-ons and modifications. Then, Project Daily Driver will take on the true feeling of a lowered sport truck. However, before we jump ahead of ourselves, let's delve into Phase II.
Phase II
Prior to the suspension installation, we ran a series of baseline tests at nearby Los Angeles County Raceway and, after some coaxing, got the big-boy truck down the track in 18.05 seconds at 75.81 mph (uncorrected) in the quarter-mile--respectable times, but not good enough in our eyes. So began the modification process.
We added many quick and easy bolt-on power products that are 50-state emissions-legal and can be installed by the average truck owner using a variety of handtools. The first modification was to the exhaust system. Gibson Performance Exhaust Systems installed a set of its new shorty headers. Constructed of rugged 14-gauge mandrel-bent tubing, heavy-duty 3/8-inch exhaust flanges, and 3/8-inch collector flanges, these headers are designed to reduce exhaust gas restriction and help dissipate engine heat more rapidly. A unique feature of the shorty headers is that no cutting or welding is required to rehook the exhaust collector to the stock exhaust pipe.
We also added an all-stainless steel free-flowing Gibson after-cat system that includes a new head pipe, free-flow muffler, and tailpipe.
The other engine mods were limited to Hypertech’s new Power Programmer Plus and 160-degree PowerStat thermostat. The Power Programmer Plus simply interfaces with the truck’s Data Link Connector, conveniently located under the dash and to the left of the steering wheel. Once it’s connected, follow the instructions displayed on the screen of the small handheld Hypertech computer. Installing the PowerStat thermostat is a simple remove-and-replace operation. We also installed one of K&N’s new High-Flow cleanable air-filters.