Blower cooling and a rear engine, somehow, this simply fits together. Only a few manufacturers, e.g., Citroen have combined the front motor with air cooling. In rear engined cars, the distance from the radiator to the engine is too great. Apart from that, the radiator reduces the already small volume of the front boot. It is also quite practical to sit in front of the noisy engine instead of behind it. The lower weight of the air-cooling also benefits the otherwise problematic chassis-layout. In the above picture, a modified Beetle engine with a radial fan from the early 1970s can be seen.
For this type of cooling, a belt-drive is necessary, because the air leaves the blower in a radial direction. This goes, see picture 1, from the crankshaft to the alternator, whose shaft is extended to the rear, into the large, in this case, gold painted housing. In picture 2, inside the housing, a small part of the thus powered fan-wheel can be seen. As can be seen by the belt-drive ratio, the fan-wheel turns a little faster than the crankshaft. In the direction of traffic, the air-flow is targeted to the center of the left- and right-hand cylinders of the four-cylinder boxer-engine. The exhaust pipes leave the cylinder heads from the front and from the rear, whereby, the front pipes still have to go through a heat exchanger for the interior heating. This air, as can clearly be seen in picture 1, is diverted from the cool air flow, before it reaches the cylinders. After running a somewhat complicated course, all four exhaust pipes meet together just before the flange (with four screws) where the gas is conducted, in a special loop, through the two exhaust pipes, where it finally reaches the open air. Not to be seen in the pictures, is a bellows-thermostat below the right-hand cylinder bank which is mechanically connected to four flaps which control the air-flow between the blower and the cylinders. Also in picture 2, a bulge can be seen, behind which the oil-cooler is hidden. This also requires sufficient cool air.
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