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It's also the gigantic whirring fan on air cooled engines that is removed with water cooled engines which lowers the noise down significantly. One of the initi
by brc 11y ago
It's also the gigantic whirring fan on air cooled engines that is removed with water cooled engines which lowers the noise down significantly.
One of the initial engine designs for the 911 was a twin-fan engine. Apparently it made such a racket that the porsche engineers nicknamed it 'the threshing machine' and Butzi Porsche canned it on the spot.
- grecy 11y agoI don't think I've ever seen a water cooled engine that doesn't have a radiator fan (or two). Older ones are crank driven, these days they're electric.
- brc 11y agoSure, and the crank driven fans have been replaced by much quieter variable speed electric fans as you noted. These are also more efficient as they can be switched off during highway driving. There are also the thermo-couple engine fans where the amount of fan-clutch engagement is driven by engine heat. My other car has one of these and sounds horrendous when driving in heavy traffic on hot days, but is mostly silent all the other times. But the big difference between a Porsche air-cooling fan and a crank-driven engine fan is that a Porsche fan is overdriven and much larger (diameter and blades) than a typical water cooling fan which is typically under driven and has fewer blades.