The high-pitched cries of steam whistles will fill the air at the Steam Festival in Willits. The nonprofit Roots of Motive Power, which hosts the annual event, revs up its antique engines for the special day while, across the street at Recreation Grove Park, the Early Day Gas Engine Society and Bill Rose’s Model A Tour group display vintage vehicles. The park will also be the site of a barbecue featuring smoked whole pigs. The event happens September 11–12 and is free, except for the barbecue, which is $20. See rootsofmotivepower.com for more information.