[Mgb-v8] [!! SPAM] Re: Ah, the details........

[David Kernberger]

dHoward,

	I don't want to be too anxious but I really do want to see if 
I made a careless error, or are really saying the same thing and have 
just misunderstood each other.

Cheers,
Dave K.

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Howard,

	Thanks for the feedback.  I agree with you 100%.  Isn't that 
what I said??  Or did I make some careless error of my own?? 
Actually I didn't mention the compression stroke at all, I don't 
think.  There is only a relatively small side thrust there.  I was 
only comparing the 2 "down" strokes, intake and power, because the 
message I was responding to mentioned only "down" strokes.

Cheers,
Dave K.

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>Hi David,
>It does muddy the water as it is wrong. The thrust face is forced 
>against the cylinder wall much harder on the power stroke than on 
>the compression stroke. Ask any piston manufacture.  I was "Product 
>Information Manager" for a major piston manufacture and at times 
>handled the liability claims for two major engine parts manufactures 
>and Importers of import car parts and had to examine many failed 
>pistons for evaluation of cause.
>
>Howard Fitzcharles
>
>------------------------------------------------------------------
>
>
>IS this still an unanswered question?  In case it is, I will give it a go.
>
>   By convention a down stroke is when the piston is moving
>towards the crankshaft (ie POWER and intake strokes) and an upstroke
>is when the piston is moving away from the crankshaft (ie compression
>and exhaust strokes).  During the power stroke the force of
>combustion is downward (toward the crank) on the piston but the
>upward resistance offered by the connecting rod and crankshaft is
>partially sideways because the rod is at an angle. The result is the
>piston is jammed against one side of the cylinder more forcefully
>than the other.  That side is the thrust face.
>
>   Therefore, as stated below, the small end of the rod will
>always point toward the thrust face whenever the piston is on a
>downstroke.  But it is only on the power stroke that there is enough
>force for it to matter very much.  On the intake stroke, there is
>essentially no side thrust at all, simply because cylinder pressue is
>relatively low.  In fact the pressure is below atmospheric
>
>I hope that doesn't muddy the waters.
>
>Dave K.