2005 Pontiac GTO - LS2 Heads/Cam Swap

The A/C fitting in front of the condenser is connected and tightened with a 17mm wrench. The bypass and vent line are reinstalled, and the intake drops back on.

The intake's bolts are tightened, and the front passenger-side purge solenoid bracket and ground are reinstalled. The injector connectors and clips are reinstalled, and the air intake goes back on.

We'll be using COMP's 7638-16 hardened pushrod kit ($130). These 7.4-inch, 5/16 Magnum pushrods will strengthen this typically weak link in the LS2's valvetrain, as the stockers are non-hardened. Once all 16 are in, the rocker arm assemblies go back on. A base spec of 22 ft-lbs is called for; however, at that rating Speed Inc. has seen them loosen up. Although you have to be very careful going tighter as you could pull threads, you may want to snug just a bit tighter than that (I suggest asking a pro before attempting this).

The valve covers go back on. NGK TR6 plugs will be used, 4177s for use with our nitrous system. Once in, the wires go back on and the dipstick tube is reinstalled. The coil pack assemblies go back on, are bolted up, and the white coil harness is plugged back in and secured with the blue clip. The wires are snapped into the coils.

The driver-side fuel line and vent lines are reconnected. From underneath, the two lower front cover bolts go back in, and the header clamps are reinstalled.

Since the new rev limit will be 7,000, and we'll be shifting right around 6,700, we need to adjust the nitrous shut-off point from 6,000 to 6,400. This is done through the FJO software. With that accomplished and the Goat almost ready to tune, a trip was made to Schaumburg Motor Works (www.schaumburgmotorworks.com) to refill the nitrous bottle.

Speed Inc was ready to start the tuning process when we discovered that our LS2 Edit-tuned ECM was locked and there was no way to bypass it, save for going to a GM dealership and getting a new ECM with the stock tune. Luckily, Rockenbach Chevrolet in Grayslake, IL, (847/223-2234) was able to lend a hand. Service Manager Darren Mooneyham is a fellow hot rodder and a Speed Inc. customer, and he was happy to help out. Mooneyham had an '05 ECM in stock, so Rockenbach installed it with a stock tune, and even gave us a free wash before we headed back to Speed Inc for tuning. A huge thanks to Darren and the Rockenbach crew--you really saved our bacon!

Up top, Dan takes the time to reattach the nitrous wiring and lines that were undone before. The strut tower brace goes back on with the purge solenoid and nitrous box. With everything reconnected, the coolant is reinstalled, and some fresh Mobil 1 and a new filter are added. Almost done...

Jim Moran will be handling the dyno tuning for our '05 GTO. "Unlike LS1s, LS2s seem to like a little more fuel on the top end," Jim explains. He starts out by increasing the idle speed, along with the startup and base airflow tables. The rev limiter is raised to 7,000 rpm, catalytic overtemp is disabled and the power enrichment eq. ratio is initially set at 1.18. Then Jim moves on to the main spark table and brings WOT timing to 22 degrees at peak torque, and 27 degrees at peak horsepower, blending into the surrounding cells. Timing at idle is also increased to the 24-27degree range. The PE spark advance correction table is zeroed out and the IAT spark advance correction table is adjusted to be less aggressive. Cat lightoff spark is also zeroed out. After that, torque management is reduced or removed along with skip shift, cooling fan duty cycle is increased and the car is ready to be started and brought up to temperature. Once it is in closed loop, Moran monitors the fuel trims and makes adjustments to bring them slightly negative. At that point the Goat is ready for a WOT pull, and the air/fuel ratio will be monitored/adjusted--so will the timing table if there are any areas that are getting knock retard. Once the tune is zeroed in (and if we had an auto), he would set the shift points on the dyno.