That's not really a 'however'. Higher temperature coolant will reject the same amount of heat through a smaller radiator with less air flow to the ambient air temperature. Less radiator frontal area and less air flow through it translates to less aero drag, and thus better fuel mileage.
Higher compression ratio and higher expansion ratio go together because of mechanical necessity. It's really the higher expansion ratio which ends up converting more of the heat energy released by burning the fuel into mechanical energy, thus leaving less waste heat to be rejected via coolant and exhaust, thus resulting in a more efficient engine. Greg Ben Ament wrote: However, newer automotive engines with higher compression are designed to run much hotter than their older counterparts. These engines often run 200+ without breaking a sweat. Because of modern coolants and sealed, pressurized systems they rarely 'overheat.' Peace, Ben -----Original Message----- From: [email protected] [ mailto:[email protected] ] On Behalf Of Greg Hermann Sent: Sunday, March 30, 2014 10:01 PM To: Graham&Joan Hilder; alfa Subject: Re: [alfa] ALFA DIGEST - Old-time radiators - reply Another factor in the older cars' tendency to overheat was lower compression ratio (as was necessitated by lower octane fuel. A lower compression engine rejects a lot more heat both to the exhaust and to the water jackets. Greg Graham&Joan Hilder wrote: Interesting to read everyone's recollections! I can add that when I was young, my Dad had British cars from the early 1950s, things like the Hillman Minx and the Standard Vanguard, and I recall that in winter he'd sometimes stuff a wad of newspapers down between the grille and the radiator, to speed the warmup on a cold morning. His workplace was only about a couple of miles away from home, and on a freezing frosty or foggy morning before the sun was high the car would never warm up otherwise. I also recall that in my earlier years, say the 1950s and 60s and maybe into the 70s, it was common in NZ to see cars stopped at the roadside with bonnets up and drivers standing by, waiting with a handful of rags and a bottle of water , to top up the boiled-over radiator when things had cooled down a bit. In NZ we had a great many old British cars in those days and I suppose most of them had pretty tiny radiators (made for freezing English weather, perhaps?) that couldn't really cope with an NZ summer, especially on a long hill or in a slow traffic jam. (Also, those cars were mostly low-powered engines and with only three-speed gearboxes a long hill could mean a long slow crawl up in second gear - lots of overheating potential.) And of course no cars of that variety had electric cooling fans either. Such cars wouldn't have had sealed pressurised cooling systems either, as Les Singh mentioned, nor antifreeze in the water, so their boiling point was much lower than in today's cars too. The first car I had with such a system was a Morris 1100 of the early 60s, and such a system was quite advanced for a British car of those years. (The old 1100 also had disc brakes in front - that was pretty special too!). We don't know how lucky we are now! Best regards, Graham H, NZ (Alfasud, GTV, 156) http://www.avast.com -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected] -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected] http://www.avast.com -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected] ----- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3722/6770 - Release Date: 03/30/14 -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
