Trying to use EPR to set takeoff thrust but it is not very accurate. I have a feeling it may not be correctly modeled in the sim to begin with but wondering if anyone can shed some light. Regardless of the conditions EPR never seems to correctly correspond to N1. For example for one of my aircraft, even at full power the max EPR I get is 1.3 or so which is no where close to the suggested takeoff EPR value. For another one of my aircraft at idle power the EPR is around 1.5 but when I bring it to the suggested takeoff EPR setting I am only getting about 70% N1 which is not enough power either. If I bring it up to the suggested N1 value for takeoff, EPR is instead about 2.1 or 2.2. Any ideas?

Really any temp but when I really got to testing was just using standard temp and pressure. Model aircraft? SGA MD-80 and JCA MD-88.

Sounds like you're an MD-80 guy, so go and get the one MD-80 that absolutely does work true to McDonnell's figures. http://www.flythemaddog.com/

Thanks for the suggestion, little out of my price range I think.