The earliest engines were cooled mainly by being too often unable to run long enough to overheat. As designers confronted the heat issue, they added secondary heat dissipation surface in one of two ways: By surrounding the hot parts – head and cylinder – with a water jacket, and then conducting the heated water to something with a lot of extra surface area – like a home heating steam radiator – the heat was dissipated to passing air. By attaching the secondary surface area directly to
