Using pressure formulas we compute the Hausdorff dimension of the basic set
of 'almost every' C1+alpha horseshoe map in R-3 of the form F(x, y, z) (y(
x, z), tau(y, z), psi (z)), where \psi\ > 1 and 0 < \y'(x)\, \tau'(y)\ < 1/
2 on the basic set. Similar results are obtained for attractors of nonlinea
r 'baker's maps' in R-3.