  A state-of-the-art 3+1 dimensional cascade + viscous hydro + cascade model
vHLLE+UrQMD has been applied to heavy ion collisions in RHIC Beam Energy Scan
range $\sqrt{s_{\rm NN}}=7.7\dots 200$ GeV. Based on comparison to available
experimental data it was estimated that an effective value of shear viscosity
over entropy density ratio $\eta/s$ in hydrodynamic stage has to decrease from
$\eta/s=0.2$ to $0.08$ as collision energy increases from $\sqrt{s_{\rm NN}} =
7.7$ to $39$ GeV, and to stay at $\eta/s=0.08$ for $39\le\sqrt{s_{\rm
NN}}\le200$ GeV.
  In this work we show how an equation of state with first order phase
transition affects the hydrodynamic evolution at those collision energies and
changes the results of the model as compared to "default scenario" with a
crossover type EoS from chiral model.
