Abstract: Disclosed herein is an oilless air compressor having a cooling system with a drive unit operating a crankshaft disposed within a crankcase and to which is attached a pair of pistons movable within corresponding compression cylinders. A blower wheel is concentrically mounted to the crankshaft adjacent the exterior of the crankcase. Each compression cylinder includes a thermally conductive cylinder insert which a bore in which the corresponding piston rides. A thermally conductive heat sink having a plurality of annular cooling fins is cast integrally to the outer diameter of each cylinder insert and connected to the crankcase such that the compression cylinders and the crankcase are completely enclosed. Each cylinder insert is made of an aluminum alloy, preferably having a low silicon content and a high melting point so that it can be insert cast within the cooling fin and anodized without degrading the surface finish of its inner bore.