GM reportedly stopped the research & development for an L3B-based sixer in 2022, which is a bit of a downer. Even Chrysler found the resources to develop a straight-six lump, namely the Hurricane engine of the Wagoneer and Grand Wagoneer. Said engine will also phase out the 5.7-liter HEMI V8 in the Ram 1500, beginning with the 2025 model year.
The Cylinder Set Strategy won't stop here, though. According to peeps familiar with General Motors, there is a 2.5-liter turbo four in the works. Think of it as the more compact sibling of the 2.7 mentioned earlier. The good folks at GM Authority claim that more details will become available in the near future, most likely referring to the projected output ratings.
Developed from the outset as a truck engine, the L3B comes to life at Spring Hill Manufacturing. Its block and head are cast from aluminum alloy, which leads us to believe that GM will use cast aluminum for the 2.5 as well. Gifted with a DOHC valvetrain with both VVT and VVL technologies, the L3B boasts Active Fuel Management. In other words, two cylinders can be shut off to conserve fuel under light load conditions.
Mated to either an 8- or 10-speed transmission, depending on application, the L3B further stands out with its active thermal management system. The party piece, however, is the dual-volute turbine housing of the BorgWarner-supplied turbocharger.
Make that two volutes integrated into the exhaust manifold, with each volute handling the exhaust gases from two cylinders. Why this design, though? The gist of it comes in the form of minimized positive pressure going back into the 2.7-liter engine. Said volutes dump the yucky stuff on opposites sides of the turbine, meaning that said pulses don't overlap.
It's pretty obvious that all of the aforementioned technologies will be carried over by the 2.5, including the clever turbo. Big torque is also a certainty, more so if we look at 2.7's output ratings. For starters, the L2R pumps out 237 horsepower and 259 pound-feet (351 Nm) in the Colorado. As for the Silverado, that'd be 310 horsepower and 430 pound-feet (583 Nm). For 2024, the Silverado's base engine has received the TurboMax moniker. In the Colorado, the very same engine is advertised as the 2.7L Turbo High-Output.