ORIGINAL: FISH KILLA

What happens when a engine over heats that affects the life of the engine?
Seeing as how the sleeve expands faster than the piston one may seem to think that when you overheat the sleeve expands so much that you lose compression and then it will die due to the compression loss right? But once it cools back down what irreversible changes occur that hurt the life of the engine. Is it because at a certain temp the piston does expand say over 300 degrees and then grinds away at the sleeve??? Or is it the protective film left on the internals from the castor and synthetic oils are burned away at those higher temps and then you risk metal to metal contact wich increases friction and heat and it chews up the sleeve? Just wondering. What is the science behind it?

ORIGINAL: acexxxoasis

well the sleeve AND piston expand and when the sleeve expands onto the expanding piston your adding pinch to something that requires certain tolerances to keep compression, also when running hot your usually overly lean and your engine isnt getting the proper lubricant so things heat up more and wear MUCH faster also your connecting rod heats faster trying to pull heat from the piston so it heats up and you can over stress the connecting rod you can stretch the bushings. this is after a long time running like this. short periods wont kill your engine but youve got a track record with engines

ORIGINAL: nitrorcjunkie


When the sleeve heats up and starts to expand, it grows in outer circumference, the diameter of the inside of the bore will increase, not pinch down around the piston. This is due to the fact that, on a molecular level, metal expands in all directions equally- picture the individual molecules of metal as balloons being inflated. Since the cross section of the sleeve is say, .125" and the circumference is around 1.25" the increase in circumference is 10 times the increase in wall thickness. Look at it this way- if you have a metal rod with a diameter of .125" and 1.25" long, when heated, the length would increase more than the diameter would. So, when you overheat the motor, the sleeve will not squeeze tighter on the piston due to the sleeve expanding, however the piston is also expanding and increasing friction between piston and sleeve. This excessive wear ruins the pinch, wearing out the motor. High engine temps destroy the lubricity of the oil, wearing out rod bushings and bearings that are designed to be constantly lubricated. How's that for some science content?[8D]

ORIGINAL: nitrorcjunkie


When the sleeve heats up and starts to expand, it grows in outer circumference, the diameter of the inside of the bore will increase, not pinch down around the piston. This is due to the fact that, on a molecular level, metal expands in all directions equally- picture the individual molecules of metal as balloons being inflated. Since the cross section of the sleeve is say, .125" and the circumference is around 1.25" the increase in circumference is 10 times the increase in wall thickness. Look at it this way- if you have a metal rod with a diameter of .125" and 1.25" long, when heated, the length would increase more than the diameter would. So, when you overheat the motor, the sleeve will not squeeze tighter on the piston due to the sleeve expanding, however the piston is also expanding and increasing friction between piston and sleeve. This excessive wear ruins the pinch, wearing out the motor. High engine temps destroy the lubricity of the oil, wearing out rod bushings and bearings that are designed to be constantly lubricated. How's that for some science content?[8D]

ORIGINAL: FISH KILLA


That is what I thought I got out of all the articles i have read. Why can't these engines use a ringed piston?

Mcanan I was not refering to my latest engine failure. And there was not any rust on it either??? Where did you see rust?

And my engine did not overheat but one time a couple gallons back. It hit like 280 something. I killed it and let it cool back to 200 and kept going.