An enhanced navigator-gated 3D-SPGR (eNAV-3D-SPGR) enables free-breathing T1-weighted abdominal MRI with navigator echo signal enhancement. In this study, we calculated effective flip angle of eNav-3D-SPGR in simulation and examined its validity for obtaining desired contrast. Simulation shows that the effective flip angle of 30° was achieved with eNav-3D-SPGR when the flip angle was set to 36.8°. Actual scan resulted in the similar signal ratios between the conventional method with flip angle 30° and eNav-3D-SPGR at flip angle of 37°. eNav-3D-SPGR with the desired effective flip angle can be useful for accurate motion detection when the liver MRI signal is low.