If the car won’t accelerate beyond 40km/h, it could be because it has gone into limp-home mode in order to protect itself from further damage. If so, that’s possibly because there’s a major problem somewhere in the driveline. But the chainsaw noise is pretty worrying, too, and suggests that something is rubbing on something else that shouldn’t be. The best advice is to not drive the car any farther until it’s been checked by a mechanic. Continuing to drive it risks doing more damage to whatever is already wrong with it.