Heartbeat – Pontiac G8 GXP

G8 GXP Heart Transplant

Photo credits by Barry Kluczyk, GM EFI contributing writer/photographer

Livernois Motorsports took the already-rare Pontiac G8 GXP and transformed it into a one-of-a-kind, Heartbeat-powered monster. What started as a simple blower upgrade evolved into a full-scale engineering feat: a custom-adapted Magnuson Heartbeat supercharger, a 419ci stroker LS3, a return-style fuel system, methanol injection, and countless hand-fabricated components to make it all work under the G8’s skin.

The result is a brutally efficient, cool-running, 733 RWHP street car with manners, muscle, and craftsmanship you won’t find anywhere else.

Below is a visual deep dive into the precision, problem-solving, and sheer ingenuity that brought this build to life.

Read more about the entire build in GM EFI: Livernois Motorsports’ G8 GXP “Heart” Transplant

Magnuson’s TVS 2300 Heartbeat supercharger is slated to provide the boost for our G8 GXP. At roughly 6 psi it adds about 125 hp over a stock LS3, and this test unit sports a polished lid for extra visual appeal.

Time to retire the factory setup — the G8 GXP’s 6.2L LS3 is pulled to make way for its Livernois-built 419ci stroker transformation.

The rebuild starts from the bare block, which is align-honed and fitted with ARP main studs. Because studs don’t twist like bolts during tightening, they deliver more consistent torque and more uniform clamping force.

A Livernois-spec Manley 4340 forged crank with a 4.00-inch stroke is the key to stretching the LS3 from 376 cubic inches to 419 — a 0.38-inch increase over the stock stroke.

Manley Forged H-Beam Rods and Livernois-exclusive Ross Racing Pistons (thermal coated) round out the rotating assembly. Compression is set around 10.3:1 to keep the boosted combination safe and knock-resistant.

The lower cylinder walls need slight clearancing to accommodate the longer rod swing — shown here by the small notch at the upper right of the bore.

For airflow, the stock heads were replaced with Livernois CNC‑ported LSA Stage 3 Castings . They move 360 cfm on the intake side and are built with 2.160" intake valves, 1.590" exhaust valves, dual springs good to .690" lift, and titanium retainers.

A custom Innovators West 10% overdrive damper with an 8-rib blower pulley handles drive duties. Inside the lightweight aluminum shell is a steel hub and a wet friction clutch pack with spring-loaded inertia rings to control crank harmonics.

The short block is now assembled and ready for the oil pan and accessories before going back into the G8. A comparable boost-capable long block from Livernois typically costs around $11,750 as of January 2015.

With the long block installed, the Magnuson Heartbeat supercharger is carefully lowered into place. It’s a tight squeeze under the cowl, but once the lid is on there’s roughly an inch of clearance.

The liquid-to-air intercooler system’s heat exchanger is mounted behind the grille — standard procedure for a setup like this.

Thanks to the Heartbeat’s excellent thermal efficiency and the added help of methanol injection, Livernois kept the kit’s original intercooler pump.

Several custom tweaks were required to make the Heartbeat fit, including shaving the top of the water pump to clear the throttle body.

The polished supercharger lid is bolted down, setting the stage for the upgraded fuel system installation.

Injector Dynamics ID850 injectors are supplied by a dual-pump, OEM-style fuel system to ensure proper fueling across the rpm range. The engine also uses an Alky Control methanol injection kit to cool the charge air and prevent detonation.

Switching to a return-style fuel system keeps pressure stable during sudden high-demand situations like WOT under boost. That change required a new Weldon High Performance Bypass Fuel Pressure Regulator, shown here.

A number of small under-hood components needed relocation or adjustment — such as the power steering reservoir — similar to what you’d expect with many aftermarket blower kits.

A GM-style 90mm throttle body feeds the Heartbeat supercharger. Straightforward and effective.

Livernois fabricated the intake system by modifying one of their Gen-5 Camaro kits to match the throttle body’s angle and position. The challenge was maintaining enough straight tubing for accurate MAF readings.

Near the end of assembly, a 3.2-inch drive pulley is installed on the blower shaft. Paired with the Innovators West damper, the setup produces roughly 11 psi of boost.

Coolant is added to the dedicated liquid-to-air intercooler circuit, with an electric pump circulating fluid exclusively for the supercharger system.

Here’s the completed installation. Despite being a custom job, it looks like a purpose-engineered kit. Livernois estimates a Heartbeat install like this — tuning included — at around $10,950 as of January 2015, not counting the return-style fuel system or engine build.

On the Livernois Dynojet, the meth-assisted, Heartbeat-equipped 419ci LS3 delivered 733 rwhp and 662 lb-ft. The car remains remarkably street-friendly — daily-driver manners with serious punch.

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