It's been fantasized, talked about, and even done a few times, but twin-turbos on a V-6 Buick-the quick-spooling, hard-charging stuff of legend-can now be considered mainstream. ESP Products poured hours of research and development into its brainchild, which has finally matured into a manly collection of Jet-Hot coated stainless steel hot parts, intake tubing, miscellaneous hardware, two T3/T4 hybrid turbos, two TiAl wastegates, and an air-to-air intercooler up to the task of 800 hp. ESP's John and Tony Perri said the twin-turbo kit was designed to provide quick throttle response and zero turbo lag in any Turbo Buick, despite its power level. The Perri brothers say that the kit can surpass the performance of a single turbo setup with less boost, which ultimately results in lower cylinder temps, less detonation, and fewer blown head gaskets (as well as increased engine reliability and durability). Typically, ESP runs the two 50-series turbos up to 18 to 20 psi (when set to kill), though they can easily push 23 psi-a stark contrast to the 24 to 30-plus pounds per square inch commonly seen in the single-turbo Buick crowd.
We decided to take a ride out to Pottstown, Pennsylvania, to check out ESP's twin-turbo kit firsthand. When I caught up with John and Tony earlier this year, they had already made over 650 hp at the wheels on their Regal shop car, which they used to design the kit. Now it was time to install the kit on customer Paul Brous' more modestly equipped '87 GN. Previously, Paul had ATR headers feeding a TE62 turbo with an ESP front mount air-to-air intercooler, a 3-inch intake and downpipe, and a stock wastegate propelling his stock bottom-end 212/225-duration ESP roller cam CNC-ported stock heads combo. In addition to swapping over to the twin-turbo system, Paul also changed from the Translator Plus-tickled stock PCM to a FAST XFI setup, along with a few fuel system upgrades, as the prior 50-pound injectors and mostly stock fuel system would soon be inadequate.
Despite his stock short-block, Paul already invested in a fortified tranny and 10-inch 3200-stall converter, which ESP said suited the new combo. After getting his GN on the dyno, Paul plans to upgrade the short-block with an ESP girdle, forged pistons, and a fresh rebuild. Meanwhile, ESP is putting the wraps on a Stage I motor for its shop car to facilitate the testing of a 1,200hp kit with a larger air-to-air intercooler and wastegates, and GT61 dual ball-bearing turbos. We hope to bring you more on that soon, but in the meantime, see how Paul's build went together. His previous best of 373 rear-wheel horsepower and 416 ft-lb of torque was made at 24 psi-could ESP improve that?
ESP sends all of the stainless steel hot parts-including the two 3-inch downpipes, turbine housings, and 1.5-inch turbo manifolds-to Jet-Hot for a 2,000-degree thermal coating. The two turbos come from a local supplier and feature a 50-trim T4 compressor and Stage 3 T3 turbine. A .63 A/R is standard, though a .48 is available for faster spooling, and an .82 works for greater top-end power. Pennsylvania supplier Blouch Performance Turbo custom-designed the turbos for ESP's kit to work at the desired boost level and engine size with the goal of achieving 800 hp-and the entire kit is US made! | 
Though Turbonetics wastegates were used in this build because of time constraints and availability, TiAl 38mm wastegates will be used in the 800hp kit. | 
The two turbos are connected to a single front mount, 30x20x4.5-inch, 16-row, bar and plate air-to-air intercooler via 2.5-inch diameter tubing. Chilled air enters the throttle body through larger 3-inch tubing, and high-quality rubber hose and band clamps connect the piping. |