Date: Sat, 29 Jul 2000 08:56:27 PST From: mojavegnopsamsp.com (Everett M. Greene) Subject: Re: How hot is too hot?
> "William Brooks" <sea.brooksnopsamdnet.att.net> writes: > > "Andrew Stephenson" <amesnopsamrak.demon.co.uk> wrote > > > > Cannot help with a yes/no, or even absolution for your misdeeds. > > But let's do some sums. Not knowing how heavy your car was that > > day, or what the average gradient was, I'll have to work in terms > > of 1,000 Kg mass (1.102 short tons) and slope of 1:6. At 70 mph, > > the power you were asking the engine to deliver, just to lift the > > car up that hill, was approximately > > (1000*9.81)*(70*0.447*(1/6)) = 51159.15 watts > > which is > > 51159.15 / 745.7 = 68.6 horsepower (roughly) > > > > Adjust the figures to suit reality. I'd say you were working it > > pretty hard, especially when you allow for AC, power loss in the > > transmission and at the tyre/road interface and, at that speed, > > maybe also air resistance and momentum lost to bugs smacking the > > bodywork <g>. Some (over)heating should be too surprising. > Good guess on the slope of the grade... but a 9000T with an automatic weighs > around 3200 pounds. So, factoring that in to your equation (of which I'm > pretty impressed) it was more like 100 horse power. Still, I would think > that sufficient cooling capacity to handle the engine's rated horsepower > (160) would be a given. One tidbit I picked up from watching some documentaries on cable channels is that "civilian" cars' cooling capacity is /not/ designed for continuous full load. Police cars have enhanced cooling systems to allow them to operate at high speeds for extended periods. One policeman even stated that they most often run speeders who won't stop until the speeders' engine overheats and fails. I believe the same thing applies to the turbocharger on "light" vehicles (such as the Saab). Truck turbochargers are rated for (more or less) continuous full power operation while passenger cars' and pickups' are not. > I was using high octane fuel because I knew I had some hills to climb and I > didn't want the APC to have to retard the ignition to avoid pinging. I have > heard that retarding the ignition will cause the engine to run even warmer. ---------------------------------------------------------------------- Everett M. Greene (The Mojave Greene, crotalus scutulatus scutulatus) Ridgecrest, Ca. 93555 Path: mojavegnopsamSP.com Ambition is a poor excuse for not having enough sense to be lazy.
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