This paper presents a generalized irreversible Carnot-engine model that incorporates several internal and external irreversibilities, such as heat-resistance, bypass heat-leak, friction and turbulence. The added irreversibilities besides heat-resistance are characterized by a constant parameter and a constant coefficient. The relation between optimal power-output and efficiency is derived based on a generalized heat-transfer law q proportional to (Delta T)(n). Detailed numerical examples show the effect of bypass heat-leakage, internal irreversibility and heat-transfer law on the optimal performance of the generalized irreversible heat-engine. (c) 2004 Elsevier Ltd. All rights reserved.