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It has been shown in a previous work that torsional Alfv\'en waves can driveturbulence in nonuniform coronal loops with a purely axial magnetic field. Herewe explore the role of the magnetic twist. We model a coronal loop as atransversely nonuniform straight flux tube, anchored in the photosphere, andembedded in a uniform coronal environment. We consider that the magnetic fieldis twisted and control the strength of magnetic twist by a free parameter ofthe model. We excite the longitudinally fundamental mode of standing torsionalAlfv\'en waves, whose temporal evolution is obtained by means ofhigh-resolution three-dimensional ideal magnetohydrodynamic numericalsimulations. We find that phase mixing of torsional Alfv\'en waves createsvelocity shear in the direction perpendicular to the magnetic field lines. Thevelocity shear eventually triggers the Kelvin-Helmholtz instability (KHi). Inweakly twisted magnetic tubes, the KHi is able to grow nonlinearly and,subsequently, turbulence is driven in the coronal loop in a similar manner asin the untwisted case. Provided that magnetic twist remains weak, the effect ofmagnetic twist is to delay the onset of the KHi and to slow down thedevelopment of turbulence. In contrast, magnetic tension can suppress thenonlinear growth of the KHi when magnetic twist is strong enough, even if theKHi has locally been excited by the phase-mixing shear. Thus, turbulence is notgenerated in strongly twisted loops

Transition to turbulence in nonuniform coronal loops driven by torsional Alfv\'en waves. II. Extended analysis and effect of magnetic twist