BJ's '66 GTO.

Classic Pontiac owners are a rare and unique group. Choosing a Pontiac over a more mainstream Chevy or a Ford, the aftermarket certainly isn’t as catering to them as they are with the more popular makes. Many have elected to suck it up, and continue modifying their 389s, 400s and 455s. But other enthusiasts like BJ Heiden (aka FatFreeGTO), are drawn more to the EFI LS swap rather than tuning the old-school Poncho mill.

We discovered this developing story that’s been in the making for almost a year now on the LS1tech message boards. BJ purchased his ’66 GTO (the second he has owned) with a TH400 sitting behind a non-original 400 (all ’66 goats had a 389). Heiden, remembering how badly he wanted to swap an LS1 into the ’66 he had in high school, decided it was finally time to realize his 15-year dream.

The LY6 just prior to the installation. Note the original truck intake.

But instead of an actual LS1, he has elected to use the VVT 6-liter LY6 sourced from a 2008 Silverado pickup backed by a 4L80E, and topped off with an LS3 intake and stock L92 heads. Works for us, and despite BJ’s impressive selection in chassis and suspension upgrades (Hothckis springs, Bilstein shocks, a disc brake conversion, poly bushings, etc.), he has stuck to his plan of keeping the car a cruiser.

With the help of an LS7 throttle body, 1 3/4″ long-tube headers, a homemade cold air intake, and a Pypes catback exhaust system – the GTO made a peak total of 333.9HP@5410RPM and 356.5hp@4575RPM on a chassis dyne. This includes the stock VVT camshafts, LS3 injectors, fuel rails, and the addition of a Walbro in-tank fuel pump. We think with a little more tweaking and tuning Mr. Heiden will soon improve upon those numbers.

Future plans call for new rolling stock and more power, while it’s currently in the middle of a fresh respray. What we especially dig is the fact that BJ has painted the engine block and valve covers classic Pontiac engine blue. It’s a nod to the loyalists who may frown down upon his choice in power plant, but we also think it’s a nice touch that he tried to maintain its original Pontiac flavor. To follow along with the ensuing project, visit the LS1tech website for the full back story.