Twin-Turbo Pontiac G8 Offers More Doors For Family Fun

Twin-Turbo Pontiac G8 Offers More Doors For Family Fun

Over the last few years, it seems that four-door V8-powered sedans have become quite popular and for a good reason. They’re roomy, luxurious, and offer V8 power. If you’re fortunate enough to own one with an LS engine, making significant power, in our opinion, is a necessity.

Photos by: Jason McMillan

Back in 2016, Chris Merry, an automotive painter, was looking for a car to fit his family of five comfortably. The Pontiac G8 GT checked all of the boxes for Chris and his family as the car had plenty of room, good looks, and that important V8 power. 

“I bought the car because my girlfriend, and now wife, Maddie had a kid, and I had two kids. So we needed something that could fit everyone and still be comfortable. The G8’s are known for their room, plus I always wanted a V8 sedan and loved the look of the Pontiac,” Chris says.  

His buddy, Bo Harris, contacted him about a 2009 Pontiac G8 that was for sale by a mutual friend of theirs that was needing to sell the car to fund a wedding. Chris purchased the car and it served its purpose up until 2018 when it was involved in a car wreck.

“In October of 2018, I was in a front end collision with the car that ended up kick-starting the build,” explains Chris. When it came time to rebuild the G8, Chis went back to his roots and went all out on the 4-door. In his younger years, Chris got into drag racing with a couple of buddies who had some pretty quick cars. Even though they were always trying to make their cars faster, the real need for speed came from his father, James Merry, racing his sportsman car at the local track.

Chris’s goals for the G8 were straightforward when starting the build, he wanted a fun street car. “The end goal for the car is to run low 9’s and high 8’s. I wanted to be able to drive it to the track, make some test hits, and drive it home,” Chris explains. However, this was a pretty tall order for Chris since the G8 is the fastest car he had ever owned when it was stock. Going from a 14-second pass to anything in the 8s is pretty drastic. 

After the collision, the G8 was torn down and readied for the rebuild. The engine was built by Auto Dynamix, of Kalamazoo, Michigan with the help of Chris. The team decided to stick with the stock bottom end and only gapped the rings for boost. The factory camshaft was swapped out for a Lil’ John Motorsports Stage-1 twin-turbo cam. The stock 821cylinder heads were reinstalled after receiving LS3 hollow stem valves, Brian Tooley Racing (BTR) 660 springs, titanium retainers, BTR pushrods, and a valve job. The engine was then topped off with a stock LS3 intake and throttle body.

Since the plan for the 4-door involved a set of twin turbos, a big fuel system was in order. The G8 now houses a Fore Innovations triple 465 in-tank fuel combination, Bosch 210 injectors, and an Aeromotive boost reference fuel pressure regulator. The factory E38 PCM still controls the engine duties with a tune from Nick Diehl.

With the help of Auto Dynamix, Chris started with a set of Flowtech stainless steel up and forward-facing headers with 1-7/8-inch primaries and 3-inch collectors that attach to a set of Borg-Warner 366 turbochargers. Dual Tial 44mm wastegates keep the boost under wraps while a pair of Tial 50mm blow-off relieves the engine of pressure when needed. Frozenboost air-to-water intercoolers keep the air charge at bay while the 3-inch stainless downpipes let the spent exhaust gasses out. 

Since the goal of 1,000 horsepower was set, the drive train would need some attention as well. The stock 6l80e was retained for now with the addition of a Circle-D Specialties torque converter spec’d out by Next Gen Built Performance out of Carol Stream, Illinois. A Derale transmission cooler was used to combat the heat. Chris also installed a 3.5-inch aluminum Driveshaft Shop driveshaft, which connects to a Camaro SS rear differential with 3.27 gears.

The G8 chassis has also had a few upgrades, including King lowering springs, BMR Suspension’s lower control arms, Strange double adjustable coil-overs, and Hendrix engineering solid cradle bushings and offset poly diff bushings. 

Since the Pontiac is a true street car, it has a couple of sets of wheels. BC Forged RZ05’s handle the daily duties, and a set of Weld S76’s are called upon at the track. Chris uses Nitto Invo tires on the front, and Mickey Thompson tires on the rear of the G8 both on and off the track. 

Since Chris is a paint and body professional by trade, he took care of all cosmetics for the Pontiac. Chris said, “The car was a 7 out of 10 when I first bought it. Since then, I’ve fixed everything, repainted it the original color, and removed the rear wing.”

When completed, the car hit the 1,000 horsepower mark at the wheels and 990 lb-ft of torque on the dyno. And while Chris has had the car to the track, he admits he has some work to do.

“The car drives fantastic, and I can get in and drive it anywhere. As for racing it at the drag strip, I don’t have a technique yet because my first track outing was a few weeks ago at Street Car Takeover, and it was definitely a learning experience. Going from 355 horsepower to 1,000 horsepower at the wheels is a huge step that I’m slowly getting used to,” explains Chris. On his third pass with the new setup, the G8 went an 11.3 in the quarter-mile at 125 mph. 

When asked what he loves about the car, Chris said, “The best thing about the car is I can load the kids up in the car and go for a cruise and enjoy the car with them. But I also enjoy the feeling when the boost kicks in while making a pass.”

Chris is not sure how much time he has invested in his car. He said, “I have actually lost track, but more then, I care to admit. When you are building a car of this caliber, you can’t focus on the time and money spent but the memories you plan on making with it!”  Well said Chris, we couldn’t agree more. 

Chris wants to thank everyone that’s helped with the build including  Auto Dynamix, Force Engineering, MS3Pro, Maven Performance, G8Only, Nextgen Built, Full Proof Performance, Finch Fab, 417 Motorsports, Brian Tooley Racing, Fore Innovation, and Holt performance. He also wanted to give a shoutout to David Diehl, Nick Diehl, and Greg Brettin.

“I might have built the majority of this car, but without these guys, it wouldn’t be where it is today. I also want to thank my wife, Maddie, for holding down the fort and taking care of our beautiful boys when I was working on the car,” Chris says.  


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