The RAM TRX has been the ultimate performance truck for over a decade, featuring off-road capability with impressive performance, thanks to its heavy-duty, off-road suspension, combined with the 6.2L supercharged Hellcat powerplant. It’s a combination that’s gone unmatched, with only the Ford Raptor R coming close to pair high-performance with off-road capability.
From Chevrolet, GM has managed to put together a Silverado with all of the off-road capability of the TRX or Raptor R, even matching the aesthetic with its rugged looks and lifted heavy-duty suspension, but the naturally-aspirated 6.2L is substantially outclassed to the over 700hp levels that the Raptor R or TRX provides. In fact, the ZR2 is down roughly 300hp from the Raptor R or the TRX. That’s not to say the aftermarket will welcome ZR2 owners with open arms; the sky’s pretty much the limit to what you can build, but really, the ZR2 should bring that kind of power to the table out of the box. At least offer buyers the 650hp LT4 as an option, GM, c’mon…
One ZR2 owner had decided to take matters into his own hands, having a Callaway Supercharged 602 Package installed on his truck, with a few other subtle modifications. It made an improvement in its performance, but evidently, not enough after a run-in with an alleged bone stock TRX on the street. He knew he needed more, but didn’t know where to turn. After some conversations with his dealer, he was turned towards Erik Bentley of Florida High Performance.
Upon closer inspection, Erik was quick to determine that the 2023 Silverado ZR2 was actually no cylinder compression in one bank, and that half of the engine’s pistons were melted due to a severe lean condition. At this point, Erik determined it was best to pull the engine, start over from the ground up, and build a solid foundation that would make the truck reliable performance.
So out came the factory engine, in went a boost-friendly, low-compression LME 390 cubic-inch short-block. Now this wasn’t going to be a simple, slap-it-back-together job for Erik, oh no. Both he and the customer agreed to take it to the next level, and optimizing those 390-cubic inches and that Callaway 2650 supercharger. So to balance out the airflow going into the truck’s engine, a set of Kooks long-tube headers and Y-pipe, attached to the aftermarket exhaust already in-place frees up a ton of power. The 390 also benefits from an FLHP head/cam package, utilizing a BTR Stage 1 blower camshaft, and a set of LME CNC-ported cylinder heads.
They took the keep-it-simple-stupid approach when it came to the fuel system; implementing a set of LT4 injectors, while the stock high-pressure and low-pressure fuel pumps remain in place. Pump-friendly 93-octane was the fuel of choice for the truck’s owner, so a 93-octane only tune went programmed into the ECU.
A 10% overdrive harmonic balancer from Innovators West, allowing the 2650 blower to produce 12-psi of boost. N final dyno numbers have been produced for the truck, although Erik estimates it’s around 700hp at the crank, with the emphasis on reliable drivability, towing, and overall performance. It’s a reliable, stout package that will provide the level of performance the owner is looking for, for years to come.
Rick Seitz is the owner and founder of GMEFI Magazine, and has a true love and passion for all vehicles. When he isn’t tuning, testing, or competing with the brand’s current crop of project vehicles, he’s busy tinkering and planning the next modifications for his own cars.
