A multimillion-dollar investment into the General Motors Powertrain Plant in the Town of Tonawanda is expected to be made public next week. Tonawanda Supervisor Anthony F. Caruana said Thursday night that an announcement would be made next Wednesday or Thursday at a news conference.

“This is going to be great news for the town and for Western New York,” Caruana said.

Rep. Louise Slaughter, D-Fairport, in a news release Thursday, congratulated GM on its plans to upgrade the facility to produce the next-generation, fuel-efficient, four-cylinder Ecotec engine.

It currently makes the four-cylinder L850 engine used in the Chevrolet Cobalt, some versions of the Chevrolet Malibu and certain Pontiac models, as well as four-and five-cylinder engines for other vehicles.

Slaughter said the investment “affirms the competitiveness of the . . . plant and ensures it will have new work well into the future, manufacturing this new engine.”

According to the United Auto Workers, the Tonawanda plant employs about 600 hourly workers, while about 375 are on indefinite layoff.

UAW Local 774, which represents workers at the plant, announced on its Web site there would a meeting of laid-off workers at 12:30 p. m. today in the union hall at 2939 Niagara St. GM invested $100 million in the plant in 2007 to produce a 4.5-liter diesel engine as a premium option in Chevy Silverado and GMC Sierra pickup trucks. It rolled the last of its big-block V-8 engines off the line there in December, resulting in 150 layoffs.