Hi all
I don't have a degree in physics, but wouldn't the ovalling of a cylinder
show at least a slight ridge of some sort on the top inch or so of cylinder
wall that doesn't get any piston ring wear??? I stand to be corrected , but
it seems like good old fashioned common sense to me.
Jeff 1990 Westy
----- Original Message -----
From: "John Connolly" <john@AIRCOOLED.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, January 23, 2004 12:19 AM
Subject: Re: Cylinder hone -conclusion?

> while offset rods and offset pins center the rods (in the piston) and
combat
> piston slap (respectively), then the engineers would have had pistons
> designed for the 1/2 OR 3/4 side, instead of the one-piston-fits-all
> arrangement they have. I know exactly why they didn't account for it,
> because it's a minor point, AND because they'd have to tool up for 2
pistons
> instead of just one in their current supplying sceme.
>
> But all of this beats around the fact that gravity IS an issue, and is a
> prime contributor to the ovaling of VW cylinders in the Flat-4 engine. If
it
> wasn't an issue, then the cylinders would be round because of the offset
> wrist pin, RIGHT? ;-) But I've found they are not round, they oval out,
with
> the larger dimensions top/bottom instead of side/side.
>
> I will concede that I have not measured the cylinders on wasser engines,
all
> mine were aircooled, and most of those were without full flow filtration
> (type 1/3 instead of T-4). Perhaps a combination of T-1/3 flat-4 and NO
> FILTER (abrasives in the oil) combined to create what I saw/measured. And
> perhaps the addition of a filter on the T-4 and wasser engines have
> eliminated MOST of this wear; the effect of gravity is still an issue on
> boxer engines, and not at all occurring in inline ones in a vertical
> arrangement.
>
> I don't know how you can conclude that 1000+ hours of rubbing a 1lb slug
of
> aluminum in a cylinder up and down 50 times/second are going to have no
> effect on the top and sides of the cylinder, yet also have no measurable
> wear on the bottom of the cylinder (where the piston is being pulled
down),
> which is what must happen if they are to remain "round". I do understand
the
> engineering operation of the piston rings, and also know that the
pressures
> generated by the rings against the cylinder wall are magnitudes greater
then
> the ones present by gravity, BUT THEY ARE STILL UNEVEN FORCES, and this is
> what causes the problem.
>
> I respectfully disagree with you thinking my comments are insignificant;
> they ARE a source of cylinder ovaling,  you just feel otherwise (which is
> fine). I'm glad I gave you a good laugh with my comments Bob. ;-)
>
> John
> Aircooled.Net Inc.
>
> >     I had a good laugh at the idea that the angle of the bore the piston
> is
> > in and gravity had an effect on the way a cylinder wears.
>