DETROIT – Lincoln’s fullsize Navigator SUV goes all V-6, as Ford’s luxury arm tweaks the model inside and out and adds an upscale trim line for ’15.

The big move is under the hood, where the automaker swaps the model’s existing 5.4L V-8 for a new version of its 3.5L EcoBoost V-6 that promises to be the most powerful rendition of the turbocharged engine yet.

Shown here to the media, a sneak peek of the new model will be presented in ads during the Grammy Awards telecast this Sunday, and the big SUV will make its official public debut at the Chicago auto show Feb. 6.

Production begins at the Kentucky Truck Plant in Louisville, KY, this summer, and the model will hit U.S. showrooms in the early fall. Pricing is expected to be revealed in April.

The V-6 marks a step up from the 300-hp 3.7L that will go into the new Mustang. It is expected to generate at least 370 hp and 430 lb.-ft. (583 Nm) of torque, says Elaine Bannon, chief engineer for the revamped model, declining to reveal specific numbers until closer to the Navigator’s market launch.

That tops the 5.4L V-8’s 310 hp and 365 lb.-ft. (495 Nm) by a wide margin, and Lincoln officials say fuel economy will be improved, to boot. The current Navigator is rated at 14/20 mpg (16.7-11.8 L/100 km) city/highway in 2-wheel-drive form.

The new model also will have a best-in-class towing rating of 9,000 lbs. (4,082 kg), executives say. It carries over a 6-speed automatic transmission as standard but now features Lincoln’s select-shift capability when switched to sport mode.

Lincoln officials are evasive when asked if any other powertrains will join the Navigator lineup, but that doesn’t appear likely near-term. A second option is under consideration for Mideast markets, where about 2,000 are exported annually and there are concerns about the turbocharged engine’s durability, but that won’t come in the ’15 model year, if at all, one insider tells WardsAuto.

Bannon says there are no concerns that Lincoln buyers will blanch at the engine downsizing.

“They just want us to deliver the numbers,” she says. “It’s not about V-8 or V-6.”