While race-car performance is the goal of a large cross-section of enthusiasts, the key to completing a very powerful "Cam-Only" LS1 build is a delicate balance of both parts and tuning talent. As described in Parts I and II of LS1 Power Plan (HPP, Aug. and Sept. '08), a well-thought-out combination of parts for the 346-cubic inch mill can increase both power and torque without sacrificing driveability or turning your Bird into a "high-rpm" only car.
Before heading off to the chassis dyno and dragstrip to quantify the gains, in Part I of LS1 Power Plan we freed up the intake and exhaust by installing an SLP LS6 intake manifold and a Jet-Hot headers/off-road Y-pipe system, gaining almost 26 rwhp. Since the engine now has the intake and exhaust flow required to make full use of an aftermarket camshaft, Part II detailed the removal of the stock LS1 cam and the installation of an aggressive Comp Cams hydraulic roller. Once the cam was installed, the weak factory valvesprings and pushrods were addressed with a full Comp dual valvespring kit and Hi-Tech pushrods, paving the way for custom tuning to unleash the newfound power.
Now retired from daily driver duties, Harold Baker's automatic-equipped '00 WS6 T/A carries 66,000 miles and is cruised for fun and used to bracket race in the Texas Muscle Car Club Challenge Series. In addition to the components installed in Parts I and II, the car has a long list of free and cost-effective mods including a Corsa after-cat exhaust, BBK 80mm throttle body, and an aftermarket suspension.
Power Products Recap Available...
Power Products Recap
Available for all '98-'02 LS-equipped Firebirds, Jet-Hot's tuned long-tube four-into-one headers for the '00 application (PN 2533, retail $500.95) feature 1.75-inch primaries, a 3-inch collector, and a proprietary Sterling finish that will reduce both header surface temperature and look great. The Jet-Hot 3-inch Y-pipe system is unique in that it is offered with removable hi-flow catalytic converters (PN 50800, retail $485) and comes complete with welded-in O2 bungs and all the hardware required for installation.
Follow along as Matt Garzonie at Real Performance Motorsports (RPM) in Lewisville, Texas, tunes the T/A and tests it on RPM's Dynojet chassis dyno. Once the tuning and dyno testing are complete, the owner will put in some seat time and head out to the Texas Motorplex in Ennis, Texas, to reveal the performance gains on the track.
Cam Tuning: How To Avoid "One And Done"
As soon as the installation of the camshaft and valvetrain was completed, the task of tuning the car fell to Matt Garzonie of RPM. According to Matt, "Enthusiasts often don't recognize that changing from a stock cam to an aftermarket one requires significant tuning expertise. The farther a cam profile gets from stock, the greater the number of changes that must be done in order to get the engine to run, idle, and perform well across the rpm band. For almost every cam that we install at RPM, we have the 'one and done' theory, which states: 'Without tuning, the car will start exactly one time before it won't start again.' While the Bird is idling during initial start up, the computer is attempting to adjust to the changes to the vacuum present at idle. Combine that with the fuel being distributed to the engine at the incorrect pulse width for valve timing events and the computer simply can't adjust itself when the combined changes are so large."
Garzonie continues, "For LS1 and LS6 applications that do not contain the new LS2/LS3-style electronic idle air control (IAC) valve that automatically modulates the amount of air at idle, we routinely drill a small hole in the throttle body blade and adjust the throttle body and idle speed up (900-950 idle speed) in order to get the Pontiac restarted. We utilize HP Tuners' VCM Suite to adjust a number of variables including the base-running idle and airflow table, initial timing, IAC park position airflow, and the throttle follower decay and delay tables.
"After the vehicle idles, we start adjusting the amount of fuel that the cylinders are getting by using the volumetric efficiency (VE) table to trim or richen the levels at idle. Once the Pontiac is warm, it is shut down and allowed to cool. This is especially important on a vehicle with new valvesprings as Comp wants the springs to be heat cycled before being operated at wide-open throttle. In addition, by allowing the car to cool down, the process of tweaking the cold-start tune can be refined so we are sure that it will start right up and idle properly when cold.
 To maximize the potential...  To maximize the potential of the increased intake and exhaust modifications, we turned to Comp Cams to replace the mild stock GM '98-'00 LS1 cam (202/210-degrees intake/exhaust at 0.050-inch duration and 0.496/0.496-inch int/exh lift on a 116 LSA) with a Comp Cams high-rpm street-strip XER273HR grind (PN 54-444-11, retail $402.42) that specs in at 0.224/0.230-degrees duration at 0.050 and 0.581/0.588-inch lift on a 114 LSA. The cam features Comp's most aggressive LS1-based lobe profiles and carries an advertised power-band of 2,000 to 7,000 rpm. |  Since the Comp Cam exceeded...  Since the Comp Cam exceeded the factory LS1's spring rating of 0.525-inch lift, a complete Comp dual valvespring kit (PN 26921-kit, retail $670.56) was sourced to ensure that the valvetrain was up to the task. The springs support up to 0.650 valve lift and fit without the need to machine the spring seats. Included in the kit are springs, valve seals, titanium retainers, and spring seats. Rounding out the package is a set of Comp Cams Hi-Tech 5/16-inch one-piece pushrods (PN 7955-16, retail $146.34) that are produced from seamless 4130 chromoly with thick 0.080 walls and won't exhibit pushrod flex or be as prone to bending as the factory parts. |  In order to get more air into...  In order to get more air into the engine, SLP Performance offers an EGR-compliant version of the LS6 intake manifold (PN 30041, $549.95) that was used on the C5 Z06 Corvette and all '01-and-newer LS1 engines. In addition to an increase in plenum volume and intake flow over the LS1 manifold, the SLP cable-activated LS6 manifold comes complete with a pre-drilled hole for the EGR, intake manifold gaskets, and the required LS6 pipe assembly, covers, and seals. |