I think I've found the issue with KER/MechJeb not displaying the correct Delta-V and thrust numbers. It appears according to the following posts that the thrust calculation changed in 1.0 to use maxFuelFlow:
http://forum.kerbalspaceprogram.com/index.php?/topic/105996-ksp-10-isp-engine-values/ http://bugs.kerbalspaceprogram.com/issues/4937
I've modified the code for the thermal nozzles as follows and I'm seeing expected values in KER again. This is for ThermalNozzleController.cs at line 847 and includes the entire first part of the if block (everything between the brackets):
{
//if (myAttachedReactor is IUpgradeableModule) {
// IUpgradeableModule upmod = myAttachedReactor as IUpgradeableModule;
// if (upmod.HasTechsRequiredToUpgrade()) {
// attached_reactor_upgraded = true;
// }
//}
_maxISP = (float)(Math.Sqrt((double)AttachedReactor.CoreTemperature) * (PluginHelper.IspCoreTempMult + IspTempMultOffset) * GetIspPropellantModifier());
//_minISP = _maxISP * 0.4f;
//atmospherecurve.Add(0, _maxISP, 0, 0);
//atmospherecurve.Add(1, _minISP, 0, 0);
//thrust = (float)(AttachedReactor.MaximumPower * GetPowerThrustModifier() * GetHeatThrustModifier() / PluginHelper.GravityConstant / _maxISP);
thrust = ((float)GetPowerThrustModifier() * (float)GetHeatThrustModifier() * AttachedReactor.MaximumThermalPower / _maxISP / PluginHelper.GravityConstant * (float)GetHeatExchangerThrustDivisor() * _thrustPropellantMultiplier);
myAttachedEngine.maxFuelFlow = thrust / (PluginHelper.GravityConstant * _maxISP);
myAttachedEngine.maxThrust = thrust;
_minISP = _maxISP * ((thrust - maxPressureThresholdAtKerbinSurface) / thrust) * (float)GetHeatExchangerThrustDivisor();
atmospherecurve.Add(0, _maxISP, 0, 0);
atmospherecurve.Add(1, _minISP, 0, 0);
myAttachedEngine.atmosphereCurve = atmospherecurve;
}