Abstract: During operation of a single-cylinder test engine, a computer or other processor runs a simulation of additional “virtual cylinders” operating alongside the single cylinder as if all cylinders, real and virtual, were present in a real multi-cylinder engine. Temperature data from the virtual cylinders is generated, and the real cylinder is jacketed with flow passages which are supplied with heat transfer fluid at temperatures such that the thermal presence of the virtual cylinders adjacent the real cylinder is simulated. As a result of this thermal simulation, the real cylinder is able to more accurately simulate the performance that it would have if it was indeed present in a multi-cylinder engine.