We present a test to investigate cosmological time dilation in long gamma-ray bursts (t_(90) > 1.5 s) using V, the ratio of expected peak counts in 64 and in 1024 ms. The theoretical evolution of V with redshift shows that dimmer bursts have flatter peaks than brighter ones when we assume that the bursters are at cosmological distances, the bursts have standard exponential profiles, and the burst peak duration follows a power law in narrowing with cosmological redshift energy. The calculated V-distribution of long bursts versus intensity in a Friedmann universe with Ω = 1 and Λ = 0 is consistent with that found from previous results for long bursts. The estimated redshift is z ～ 2, and the time dilation factor with energy correction is ?1.8.
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