Quote:
Originally Posted by oil pan 4
Its basic thermo too, heat does the work, while trying to flow from hot to cold, if your block and cylinder head is cold energy that could have been used to push the piston down trying to reach a colder state is instead being absorbed by cold metal parts.
Cold starting them is not doing them any favors.
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You can feel this energy redirecting by the great reduction in engine power produced when pressing down on the accelerator of a recently started cold diesel engine on a cold day. Although the fuel flow rates are normal, the power coming out of the engine is way down until the engine gets up to operating tem since part of the fuel energy is going to heat up the engine block than moving the pistons. You are literally burning fuel to heat up the engine block.
As an aside, internal combustion engine cylinders are designed to get rid of heat, but steam engine cylinders are designed to retain heat since any heat energy lost to the cylinder walls is lost engine efficiency.