Nonuniversal critical phenomena along the lambda line of4He

General relations between the critical specific heat above and below the lambda transition of⁴He are derived. The specific heat aboveT is calculated in three dimensions up to two-loop order. The relations can be used to determine the effective renormalized static couplings of modelF without integrating the renormalization-group flow equations. The effect of different normalizations of the couplings is discussed. The theory is applicable both to asymptotic universal and to nonasymptotic nonuniversal properties well away fromT (P) and provides part of the basis for quantitative predictions of other nonuniversal critical phenomena along the lambda line.