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Originally posted by 1911:
1) Have you ever looked at the front of a 1973 Plymouth Valiant and then looked at a 1994 Honda Civic? You cannot even see the radiator on the civic but the Valiant has a big squared off one with a big grill.
The Honda also burns a mere fraction of the fuel that the old Plymouth did, and converts more of the fuel it does burn to useful energy than the old car did. The result: less waste heat.
Modern I-4 and V6 engines, here in Canada, with the thermostats closed, even enclosed in tight engine bays, often cannot maintain adequate temperature for maximum efficiency in the wintertime. This is a direct result of increased thermodynamic efficiency in the overall combustion process.
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2) Engines actually get a good bit (or used to at least) of their cooling from airflow under the car. It has been cut dramatically for aerodynamic efficiency and to reduce car lifting due to the airfoil effect (longer path equals lower pressure) at higher speeds. THis has been a problem for gearbox manufacturers.
Yet engines and transaxles are more reliable than ever.
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3) Specific outputs are two to six times higher than the fifties and this means a lot more heat energy produced per a given amount of metal, water volume, engine surface area (see Brother Molekules excellent posts on this for the oil pan itself), etc. This along with items 1 and 2 means higher oil temperatures today!!!!!! Look at the numberes some of the dudes on this board
are measuring with some aggressive driving!!!! You couldn't produce 275F-300F in the fifties unless your cooling system was broke.
And you couldn't drive those designed-in-the-1950s cars fast either compared to the cars of today. And while engines can produce higher specific outputs, the total output required to push a car down the road at 65mph, the speed limit, has fallen dramatically since then. And yes, I do challenge you to show me any car that has 275-300degF oil temperatures when legally operated on the highway.
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4)Higher specifica outputs also often transcribe to higher loads at the bearings which are not always compensated for (versus the 50's designs) with larger bearings (to keep the pressures the same). I bet the pressures are much higher now.
Check the bearing size of an old old Chevy V-8 and then compare to a current one of the same size.
Ignoring 40-50 years of advances in metallurgy and machining techniques, eh?
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5) Most on this board continually fail to understand what even 25 extra degrees F does to the viscosity. It is dramatically underestimated Ugly and you (not to point a finger) are one of the guilty party here. These little Honda four bangers probably run 40F- 80F higher oil temperatures than their 50's counterparts. IS that not worth a grade or two mate........? My charts say it is!!!!...your's are evidently not available.
Yet engine removal over the life of a car is a comparatively rare event these days, compared to the the 50s, 60s and 70s where a rebuild was almost a certainty after 100k miles given designs and maintenance practices of the time.
