As a refresher, we started out with a bone-stock '87 Buick GN, base-lined it, then progressively dyno and strip tested a host of proven bolt-ons. Each time we tried a new upgrade, we visited our friends at Tune Time Performance for dyno testing to see the power gains and to be sure of a safe air/fuel ratio-we didn't want to hurt our buddy Tim Cairone's Turbo Buick. By taking advantage of today's technology and 20-something years of R & D going into the TB motor, we were able to safely add over 100 rwhp, 200 lb-ft torque and lower e.t.'s by 2 seconds without changing any of the engine's internals. That was risky business and a lot of power to be gained from a motor with over 100,000 miles. This led us to freshen-up the bottom end of the original (numbers matching) 3.8-liter V-6 for the swap to the roller cam and ported heads.
Back in Part 4 we installed and tested PerformaBuilt Transmissions' rebuild of the GN's original 200-4R along with its 10-inch billet 2,800-stall converter. The PB transmission and billet 10-inch converter lowered the 60-foots from an average of 2.2 to 1.65. Quarter-mile e.t.'s dropped big time from mid 13s to low 12s. Feeling confident after testing PB's beefy trans/converter with its two-year unconditional warranty, we were ready to shoot for the 11s.
In order to run 11s without lots of boost (over 20 psi), we knew we needed to ditch the outdated stock flat-tappet cam for a more recent technology hydraulic roller-tappet stick from Comp Cams. Teamed-up with the roller stick was a set of well-ported stock iron heads by Jose Motor Sports to increase airflow through the forced-air fed Buick V-6. We planned on a budget rebuild and reused the stock cast pistons and rods instead of using a lighter and stronger rotating assembly as not to skew our test results of the swap to the roller cam and ported heads.
For this episode we'll drop in the refreshed short-block with the roller valvetrain and ported stock heads. A last minute decision was made to install a new set of stainless steel, ceramic coated headers from G Body Parts. The stock units were rusty, cracked, welded, and beyond their years of service life, besides restricting airflow coming out of the motor. For now check out the power gains we made from the added airflow being able to move more rapidly through the Turbo Buick motor. We'll go for strip test results after the winter thaw melts the snow and ice from the track's surface.