Camshaft Installation - LS7 Bumpstick Complicity!

Harken back to the heyday of the musclecar revolution and imagine using hindsight to sit across the desk at your favorite Chevrolet dealer to order up a 1967 Corvette with the legendary RPO code L88. For a scant $947.90, you could have checked the option for the aluminum headed 427 that was conservatively rated at 430 gross hp (at 5,200 rpm) and 460 ft-lbs of torque (at 4,000 rpm). The Chevrolet big-block featured a 4.251-inch bore, 3.76-inch stroke and 12:5:1 compression. With a mechanical lifter camshaft that featured 264 degrees of intake and 269 degrees of exhaust duration (measured at .050-inch lift) with .560-inch intake and .580-inch exhaust lift, it was designed to be revved to 6,400 rpm, where it would wake up and reach its power potential. This was a solid lifter race motor, never meant for daily driving. GM tried to keep the actual horsepower of approximately 500 a secret, and to a degree was successful with only a mere 216 Vettes factory equipped with the L88 from 1967-69.

Fast forward to 2006 and you can walk into your Chevrolet dealer and check off option code 1LZ or 2LZ and order yourself a new Z06 Corvette featuring the 7.0 liter (427 cubic inch) LS7 engine. The upgrade to a Z06 carries with it a $21,200 price tag, but includes much more than the LS7 engine and its crate motor retail price of $13,895 (under PN 17802397). Carrying a conservative net horsepower rating of 505 (at 6,300 rpm) and 470 lb-ft (at 4,800 rpm), the all-aluminum engine is the ultimate factory Gen IV small-block and a direct descendant of the impressive C5R racing efforts. The rigid aluminum block carries 6-bolt main caps, a 4.125-inch bore by 4.00-inch stroke, and an 11:0:1 compression rating. The hydraulic roller cam specs out at 230/231 at .050 with .591-inch lift on 1.8 roller rockers and is designed to be revved up to 7,000 rpm.

LS7 owners looking for increased power are doing exactly what the original L88 owners did; replacing the cam, exhaust manifolds and exhaust system with the best that the aftermarket has to offer. Horsepower of 550-575 was obtainable with the L88, but along with the power came a radical idle and poor street manners. Since the LS7 idles as well as any modern car of its generation, what would happen if you swapped out the cam for a more aggressive design and freed up the exhaust? Enter Horsepower Engineering (HPE) of Houston, Texas. Founded in 2001 by owner Chuck Anders, the 13,000 square-foot facility has been pushing the envelope on late model GM performance. As the shop that lays claim to the fastest LT1 F-body, along with the fastest stock block LS1 in the country, big power and HPE go together.

According to Chuck Anders, "the LS7 is a fantastic engine with excellent street manners. Substantial power gains can be achieved by optimizing the camshaft and the exhaust system. Our C6ZS2 (Stage II) camshaft package was custom designed for the owner desiring stock like drivability, moderate lope at idle and noticeable power gains. Although the Z06 features hydro-formed tubular steel exhaust manifolds and a 3-inch exhaust system, the LS7 heads are quite restrictive on the exhaust side. Anything you can do to increase the flow of the exhaust helps power on the LS7." By utilizing a set of the new D-port Kooks 1 7/8-inch headers and 3-inch mid-pipe with high-flow metal substrate cats, increased exhaust duration is allowable due to the excellent scavenging of the Kooks components. Throw in a ported HPE throttle body and a Halltech PowerCore air filter and the engine wakes up very nicely.

Follow along as HPE searches for big power on an LS7 by installing a custom ground camshaft, Kooks headers, Kooks mid-pipe with high-flow cats and a Halltech PowerCore high flow LS7 air cleaner on a 2006 C6 Z06, owned by Sanjay Mehta, a radiation oncologist from Houston, Texas. With a mere 3,500 miles on the odometer, his stock-configured Z06 belted out 465 rear-wheel horsepower. Shop manager and lead technician Josh Ledford of HPE will handle installation of the components while HPE owner Chuck Anders will dive into the powertrain control module and retune the car to maximize the power potential. After wrenching and replacing the parts, we'll show you how much power was added to a bone stock Z06. Will the LS7 respond to the changes much as the L88 did and put out close to 575 horsepower?

Remove the stock AC Delco spark plugs with a 5/8-inch swivel plug socket.	Remove the six 13mm passenger side exhaust manifold bolts.	In order to gain additional clearance to remove the exhaust manifolds and access the valvetrain, the valve cover will have to be removed. Begin by unsnapping the clip that retains the PCV hose to the valve cover breather.
Remove the four 8mm valve cover bolts and extract the valve cover from the engine compartment. Move over to the driver side.	Before removing the driver side valve cover and exhaust, the alternator will have to be removed. A 15mm wrench is placed on the bolt on the passenger side pulley and pulled toward the driver side in order to swivel the pulley and remove the belt. Once removed, the electrical connector on the back of the alternator is unclipped and a 13mm wrench is used to remove the alternator power feed wire from its post. Loosen and remove the upper and lower alternator bracket bolts with a 15mm socket and store the alternator.	Before removing additional hardware on the passenger side, it's a good idea to remove the coolant temperature sensor from the block. Remove the number-one spark plug wire from the plug and coil pack and use a 19mm socket to carefully remove the sensor.
To disconnect the fuel line from the manifold, the valve stem cap is unscrewed from the fuel rail and a Schrader valve tool is used to remove the valve. Remember to relieve the pressure slowly and to put a rag under the Schrader valve to catch any fuel from spilling onto the manifold. Once complete, go to the back of the fuel rail and use a fuel line disconnect tool to separate the fuel line from the manifold.	Disconnect the coil pack harness and remove the spark plug wires from the plugs. Remove the coil pack assembly and then remove the PCV hose from the driver side valve cover by depressing the blue connector and lifting the hose up. Remove the valve cover and spark plugs and finish off by removing the steering knuckle with an 11mm wrench. Move the steering shaft as far away from the exhaust manifold as possible and remove the six 13mm exhaust manifold bolts.	Raise the car up on a lift and use an impact gun with a swivel socket to unbolt the two 15mm bolts that attach the mid-pipe to the back of the catalytic converter assembly on each side.
Move to the rear of the mid-pipe and remove the 15mm nut that attaches each side of the mid-pipe to the cat-back exhaust. An Accu-seal clamp is utilized from the factory to create a leak-free slip fit connection. Next remove the two 13mm nuts from the mid-pipe retainer brackets that are located behind the transmission torque tube cover.	Pull the mid-pipe toward the rear of the car to separate it from the catalytic converter assembly and then push it forward while wiggling the connection back and forth until the two pipes separate from the cat-back. It may be necessary to spread the Accu-seal clamp with a small pry bar or large screwdriver, but in this case, the pipes slipped off with minimal resistance. Set the mid-pipe to the side.	Remove the electrical harness safety pin from the front and rear O2 sensors and carefully disconnect the harness mounting bracket and O2 connectors.