An auger bit is provided for a foundation pile system including a drilling rig adapted for mounting and rotating a grout pipe connected to the auger bit to form an auger. The auger bit includes a stem with lower and upper sections, which taper towards a transition whereat the stem has a maximum diameter. A pile foundation forming method includes the steps of providing a drilling rig, forming an auger with a grout pipe coupled to an auger bit, rotating the auger wit the rig, forming a borehole with laterally displaced soil, pumping pressurized grout through the auger and into the borehole, placing a reinforcing cage in the wet grout and curing same.