They can be configured for aftermarket valvetrains, including stud-mounted rocker arm systems, but the big advantage of Champion GN1 heads are in and around the combustion chambers. The chambers have a volume of 46cc while the valve centerlines have been relocated to allow the use of larger 1.90 and 1.60 valves.
The GN1 design also unshrouds the valves for maximum airflow. In the runners, volume has been increased to 159cc on the intake side and 79cc on the exhaust side. Low-lift airflow and air speed have been attended to in order to ensure responsive performance. Bolting on an average of 30 percent more flow has never been so easy. Lehmann employed T&D rockers and pushrods in his GN1s and is happy with the package.
Power application is handled by a Culhane-prepped 200R4. Steve Culhane swapped the 200R4's stock seven-vane rotor for a 10-vane unit from the 700R4. Fresh clutches were installed with third and fourth gear each getting an extra clutch. The pressure plate was machined to accept the extra clutches, as clearances are critical in the 200R4. The servo and sun shell were also addressed and the valve body was tweaked for added shift firmness.
Mickey Thompson and BFGoodrich rubber is mounted on Weld Racing aluminum. One of the best tricks for turbo Regals is upgrading the braking system. For years, ads have read, "run 12s for $600." But what about stopping? Baer Racing has developed a number of systems for the G-Body. The systems can be broken down by budget or tire size.
The Street package can accommodate stock size wheels and is less expensive than the top-of-the-line Track system. The Track system on Lehmann's car sports 13.1x1.1-inch front rotors as well as twin-piston performance calipers. A rear conversion puts a set of Corvette-spec rear brakes on the Buick.
Lehmann puts his foot into the throttle on a fairly regular basis and says the car's thrust is noticeably superior to the big-block Chevys he's owned. Czarnota says the car is detuned for street usage. With the proper octane in the tank, boost can be cranked to 24 psi, which would put output between 650 and 700 hp. In this trim, the Regal should lay down 10-second e.t.s with ease. Either way, this sleeper rocks.