  New non-linear hydrodynamic models have been constructed to simulate the
radial pulsations observed in the extreme helium star V652 Her. These use a
finer zoning to allow higher radial resolution than in previous simulations.
Models incorporate updated OPAL and OP opacity tables and adopt a composition
based on the best atmospheric analyses to date. Key pulsation properties
including period, velocity amplitude and shock acceleration are examined as a
function of the mean stellar parameters (mass, luminosity, and effective
temperature). The new models confirm that, for large amplitude pulsations, a
strong shock develops at minimum radius, and is associated with a large phase
delay between maximum brightness and minimum radius. Using the observed
pulsation period to constrain parameter space in one dimension, other pulsation
properties are used to constrain the model space further, and to critically
discuss observational measurements. Similar models may be useful for the
interpretation of other blue large amplitude pulsators, which may also exhibit
pulsation-driven shocks.
