Once again, you can see the piston differences on my web site, at
http://members.tripod.com/perlindgren/wbx.html. The 1,9 and 2,1 does not have
the same pistons.

PerL
87 Syncro 112i

kenneth d lewis wrote:

> I wrote:
> >        FWIW let's calculate stroke assuming the heads are the same.
> >Bentley only mentions one piston for both engines; 9.4 cm in diameter.
> >I come up with a stroke of 7.565cm for the 2.1L and 6.8475cm for the
> >1.9L.
>
>         In actuality, calculating stroke is independent of head volume.
> As a matter of fact; if pistons, cylinder length and head seal thickness
> are the same in both engines the head volume MUST be different. This is
> assuming a 9:1 CR in both engines. Since each piston displaces 50cc more
> in the 2.1L engine, then that volume must go somewhere for the CR to
> remain the same.
>          Is volume of each head combustion chamber 50cc bigger? I do not
> know, I am only theorizing. Lets assume this theory is correct and we
> proceed with calculating the CR of a 2.1L engine with 1.9L heads. If the
> squish volume is reduced by 50cc we have:
>
> CR= (525+15.625)/15.625
>
> CR=34.6:1!!!!!!!!!!!!!
>
>         This clearly is impossible so some or all of that extra 50cc must
> go somewhere. A clue is given on pages 13.44 and 13.45 of the Bentley. It
> shows the dish dimensions are different between the two pistons!
> Unfortunately they only gives depth measurements and not volume. So our
> CR calculations are at a stand still until we have some more data. Anyone
> out there have some pistons laying around they can CC?
>
> Drive Safely & Good Luck
> Ken Lewis<Kernersville,NC>86 VW crewcab;60 T-5 Coupe
>
> On Sat, 16 Oct 1999 00:29:13 EDT kenneth d lewis <kdlewis@JUNO.COM>
> writes:
> >Roger;
> >        This is news to me. I thought both heads were the same. The
> >Bentley refers to ONE head for both engines. Anyway, here are some
> >formulas so you can decide for yourself. First some definitions:
> >
> >Squish volume= The volume in the cylinder when the piston is at top
> >dead center.
> >
> >Cylinder volume= the volume swept by the cylinder i.e.  2.1L=525cc;
> >1.9L=475cc
> >
> >If memory serves me compression ratio is given by the following
> >formula:
> >
> >C.R.= (Cylinder volume+Squish volume) / Squish volume
> >
> >Solving for Squish volume I come up with:
> >
> >Squish volume= cylinder volume/ (C.R.-1)
> >
> >Assuming a compression ratio of 9:1 in both engine;
> >
> >Squish volume for the 2.1L= 65.625cc
> >Squish volume for the 1.9L= 59.375cc
> >
> >This supports your claim of approximately 5cc difference between
> >heads. Now lets recalculate using 2.1L volume and 1.9L squish volume:
> >
> >C.R.=(525+59.375)/59.375
> >
> >C.R.=9.84:1
> >
> >There is one important piece of data we may or may not need to take
> >into account; the 2.1L has a longer stoke. So how much of that change
> >in squish volume is due to different heads and how much is due to
> >different stroke? I will leave that question open for debate.
> >
> >        FWIW let's calculate stroke assuming the heads are the same.
> >Bentley only mentions one piston for both engines; 9.4 cm in diameter.
> >I come up with a stroke of 7.565cm for the 2.1L and 6.8475cm for the
> >1.9L.
> >
> >        That's enough math for tonite, I still have to go out and
> >finish installing the relays to boost the voltage to the headlights on
> >my transporter. I will mull these figures over and get back with you.
> >
> >
> >Drive Safely & Good Luck
> >Ken Lewis<Kernersville,NC>86 VW crewcab;60 T-5 Coupe
>
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