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GM High Tech Performance
Big Power Gains For Your LS1
Jun 2, 2003
Loganville, GA 30052
Speed Hound Performance
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Big Power Gains For Your LS1
On the Speed Hound Performance dyno, this '01 roadster registered an increase of 40 hp and 33 lb-ft of torque following installation of TPIS headers, and a Random Technology converter/X-pipe assembly and converter-back exhaust system.
Just as the knee bone is connected to the shin bone and the shin bone is connected to the ankle bone, the exhaust system is connected to the H-pipe and the H-pipe is connected to the manifolds. Before any of these subassemblies can be removed, they have to be disconnected from each other. But before unbolting any of the system...
-...the rear oxygen sensors should be removed. The sensors screw into the H-pipe behind the catalytic converters, but the harness attached to them runs forward and is attached to the heat shield with a series of clips. After disconnecting the connectors from the car harness, the clips should be pulled from the heat shield.
After all the clips are removed, pull the harness loose.
Next, remove the oxygen sensors from the H-pipe with a 7/8-inch open-end wrench or an oxygen-sensor socket.
The first fasteners to be removed are the bolts that hold the H-pipe to the exhaust system.
Next, the three nuts that hold the front of the H-pipe to the exhaust manifolds should be loosened, but not removed.
The bolts that hold the front H-pipe bracket to the bellhousing are the next to go. When they're removed, the front of the H-pipe will drop down on the manifold nuts, which is the reason they should be loosened, but not removed.
Two bolts hold the assembly to the rear hanger. When these are removed, the only fasteners holding the H-pipe in place are the nuts on the exhaust-manifold studs. With the manifold nuts loosened, the rear of the H-pipe may be lowered onto the ground or a support. Then remove the nuts on the manifold studs, lower the H-pipe/converter assembly, and slide it out from beneath the car. Since the H-pipe is over 6 feet long, it's a good idea to have an assistant help with its removal.
$^p<$E?re ready to tackle exhaust manifold removal. The driver side is the more complicated of the two because components like the steering shaft are in the way. Remove the bolt that holds the shaft to the steering box and slide the shaft out of the way.
Then remove the coil covers, alternator, and the bolts that hold the coil assembly to the valve cover.
Once all the bolts are unbolted and the connectors disconnected, the coil assembly may be lifted out of the way.
Next the fuel line can be disconnected; but before removing this clip, make sure pressure within the system has been bled off. It's also advisable to loosen the gas cap to relieve any pressure that may have built up in the tank. Leave the cap just loose enough to allow pressure to bleed off, until the gas line is reconnected.
Special plastic clips, available through auto parts stores or fuel-injection specialists, are required to pop the fuel line off the fuel rail.
Now the bolts that hold the manifolds to the head can be removed and the manifold lifted out of the engine compartment.
There isn't much in the way on the passenger side, so once the coil assembly is removed, the manifold can be unbolted...
...and extracted from the engine compartment.
Next the headers can be worked into place. It may look like a difficult task since the collectors twist around, but TPI Specialties did an excellent job of designing the headers and they are surprisingly easy to work into position.
After the driver-side header is in position, start two bolts to hold it in place, but don't tighten them.
Next, lower the passenger-side header into place and thread a couple of bolts loosely into the head.
The headers connect to the same mounting bracket as the front of the stock H-pipe. Leaving the header bolts loose allows the headers to be easily positioned to facilitate installation of the hanger bolts.
Once the hanger bolts have been started, the driver-side header bolts can be tightened.
Then the passenger-side header bolts can be snugged and the hanger bolts tightened.
Next, it's time to reconnect the steering shaft...
...and slip the fuel line onto the fuel rail and reattach the retaining clip.
With the headers in place, the Random Technology converter/X-pipe assembly can be installed. Part number 752722 is designed specifically to fit C5s with TPI Specialties headers, so installation is easy. Other models are available to fit stock exhaust manifolds.
After installing the oxygen sensor in the converters, they can be slipped into the header collectors.
Then the X-section can be slid onto the converters, lifted up into place and bolted to the exhaust system.
After the rear hanger bolts are installed and all connections tightened, you're ready for a testdrive.
TPIS long-tube headers feature 1 3/4-inch-diameter primary tubes, all the required emissions-control connections, and metallic/ceramic coating.
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As with any project, there's a right way and a wrong way to install headers. CHP talked to header manufacturers and visited Tom Dawson Racing Headers in Nuevo, California, to discover
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