Is the body code referring to the loop variables i1, … i4? Then you could start a Goroutine:
// Body code
go func(a int, b int, c int, d int) {
// do something
} (i1, i2, i3, i4) // We have to capture the values here!
But depending on how large num is and what the body code does, this may not be the best idea. You will start num^4 goroutines and if each uses some limited resource, you may overload this resource.