The president of Canadian auto-worker trade union Unifor has let slip that Ford may be working on a new 6.8-liter engine and that it would be used in derivatives of the Mustang and F-150. We expect the engine to be a V-8.

Jerry Dias mentioned the 6.8-liter engine at a Sept. 23 press conference, saying it would be built at a factory in Windsor, Ontario. An accompanying Unifor press release (via Motor1) also referenced the new engine.

"Ford has committed to source new 6.X L engines to the Windsor Engine Plant and sole source 5.0L engine assembly and current component machining to the Essex Engine Plant, along with any derivatives," the press release said.

This is part of a recently struck deal between Ford and Unifor that will also see the automaker's Oakville, Ontario, assembly plant retooled to build five all-electric models beginning in 2025. The plant currently builds the Ford Edge crossover, which is expected to be phased out.

2021 Ford F-150

2021 Ford F-150

Confirmation from a trade union is not the same thing as confirmation from Ford itself and, to be clear, the automaker hasn't said anything about a bigger V-8 for the Mustang or F-150. This wouldn't be the first time union officials spilled the beans on future Ford products though; the Ranger and Bronco were revealed in such comments long before they were formally announced.

Dias and the Unifor press release also didn't specifically mention a V-8. While Ford did build a 6.8-liter V-10, that engine was designed for larger Super Duty pickup trucks, vans, and the Excursion SUV.

Similarly, it's unlikely the 6.8-liter engine will be based on the current Super Duty's 7.3-liter V-8. That engine has an iron block, and is physically much larger than the 5.0-liter V-8 already used in the Mustang and F-150. Simply dropping in a lower-displacement version would result in very nose-heavy vehicles.

The phrasing "6.X L" also indicates that this new engine could be offered in multiple displacements, similar to Ford's modular engines of the 1990s and early 2000s.