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January 02, 2004
Hi Geri,
I am no mathematician, so I am quite happy to accept what you say, and I am not arguing with you...
but logic makes it hard to believe!
If all 4 pistons are identical, and the throw on each crank journal the same, then I cannot see why the volume displaced by one going down should be any different from the displacement of the adjacent one going up. Neither can I see why the length of con rod should make any difference either.
However I can well imagine that there are complex effects of the inertia of the air/oil vapour mixture beneath each of the pitons. The piston going down will move the vapour in contact with it first, causing a compression shock wave to travel through it rather than simply moving a plug of air down the bore.
So there will be pressure changes.
Meanwhile, in the neighbouring bore the piston will move upwards, "stretching" the air column beneath it and reducing the pressure. I guess this will all get pretty complex. I still think that the greatest influence causing the progressive build up of pressure in the sump is leakage past the rings, and, if the rocker cover is sealed, past valve guides and to the sump via the push rod holes.
Guy
"Guy Weller" < Guy.Weller@... > 27977
Posted on January 2, 2004 02:22 PM
Posted to category(s) Cylinder Head | Engine (internal) | Gauges | Ignition System | Intake System | Interior | Lubrication System | Suspension & Steering | Tuning
