PYROMETER

Hello good afternoon, I tell you that in our career car we have installed a Digatron Digital Pyrometer (the orange color) since we began to take care of the mechanics of the same we have begun to try to interpret it, the temperature is supposedly placed (1380f) and this cdo is cold is zero and then if the temperature is high as we believe it has it, since it marks ours 900, start up. If we have forged pistons it is impossible for this type of temp. We believe that we are reading it badly or we have calibrated it badly, I would appreciate your help and thanks