eyolf
Addicted to ArboristSite
I wish I could remember enough of it, but I seem to remember an article in a sno-mo magazine back in the '70's, (based on an S.A.E. paper?), that suggested heat siezes were often almost instantaneous...heat transfer was working fine from the piston to cyl, piston to fuel charge, until BANG!, something interferes with that process, or the process isn't capable of keeping up with an extremely rapid change.
Heat transfer, especially between dissimilar materials, usually becomes less efficient as the temp rises, and in some cases there are some pretty abrupt changes at certain temps. This usually has to do with things like changes in state (e.g. solid to liquid) or even more esoteric things like rapid movement of electrons into and out of energy shells, as would happen when, for instance, the aluminum in an aluminum alloy piston is getting close to melting, and may indeed only be held in place by the network of copper, beryllium, and phosphorous, etc. atoms alloyed within it.
So, at a Cyl head temp of maybe 1275, piston crown slightly higher, you're alive and well. 1290 you're courting disaster, 1295, its probably too late; 1300, you're already toast. Could an EGT or other feedback system respond quickly enough when the desired operating range may be so close to the danger zone? Wouldn't it be necessary to move the safety margin out to the point where performance would be compromised?
Gypo: regarding warranty work. I've had so few problems with warranty work on anything that I don't even consider the warranty anymore when I'm shopping for anything that costs less than a car. Since I've been earning money, only one thing I ever bought needed to go back for warranty; that was an electric drill, and it would have been easier for me to buy another one, after all the fooling around trying to figure out where to go with it.
Heat transfer, especially between dissimilar materials, usually becomes less efficient as the temp rises, and in some cases there are some pretty abrupt changes at certain temps. This usually has to do with things like changes in state (e.g. solid to liquid) or even more esoteric things like rapid movement of electrons into and out of energy shells, as would happen when, for instance, the aluminum in an aluminum alloy piston is getting close to melting, and may indeed only be held in place by the network of copper, beryllium, and phosphorous, etc. atoms alloyed within it.
So, at a Cyl head temp of maybe 1275, piston crown slightly higher, you're alive and well. 1290 you're courting disaster, 1295, its probably too late; 1300, you're already toast. Could an EGT or other feedback system respond quickly enough when the desired operating range may be so close to the danger zone? Wouldn't it be necessary to move the safety margin out to the point where performance would be compromised?
Gypo: regarding warranty work. I've had so few problems with warranty work on anything that I don't even consider the warranty anymore when I'm shopping for anything that costs less than a car. Since I've been earning money, only one thing I ever bought needed to go back for warranty; that was an electric drill, and it would have been easier for me to buy another one, after all the fooling around trying to figure out where to go with it.
ive lost too many[teeth] now so ill have to do without the goodies.later
