Date: Thu, 22 Jan 2004 23:19:21 -0700
Reply-To: John Connolly <john@AIRCOOLED.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Connolly <john@AIRCOOLED.NET>
Subject: Re: Cylinder hone -conclusion?
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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.
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