Can it be done? 20V head on a 2.3 NG?

[Alan Kramer]

Brady,
     I woudn't say highly unlikely because it is true.  Here are some good
rules of thumb for most Audi & VW engines:

2 valves / cyl = 29cc
4 valves / cyl = 46 cc

Common rod lengths are 136mm, 144mm and 160mm.

Here are some facts I've collected on engine internals in bad ascii form to
get started:
Engine Code / # Cyl. / # Valves / Rod Bearing / Wrist Pin Dia (mm) / Rod
Length(mm) / Bore(mm)

3B / 5 / 20 / 034105701A / 20 / ?   / 81
7A / 5 / 20 / 034105701A / 20 / 144 / 82.5
MC / 5 / 10 / 056105701  / 22 / 136 / 81
NG / 5 / 10 / 034105701  / 20 / 144 / 82.5
NF / 5 / 10 / 034105701  / 20 / 144 / 82.5
KX / 5 / 10 / 034105701A / 20 / 136 / 81
KZ / 5 / 10 / 034105701A / 20 / 136 / 81
WE / 5 / 10 / 056105701  / 22 / 136 / 79.5
WX / 5 / 10 / 056105701  / 22 / 136 / 79.5
WK / 5 / 10 / 056105701  / 22 / 136 / 79.5
PF / 4 / 8  / 034105701  / 20 / ? / 81
RV / 4 / 8  / 034105701  / 20 / ? / 81
PL / 4 / 16 / 034105701  / 20 / ? / 82.5
9A / 4 / 16 / 034105701  / 20 / ? / 82.5
JH / 4 / 16 / 034105701  / 20 / ? / 81
ABA / 4 / 8 / 034105701  / 21 / 160 / 81
AAN / 5 / 20 / 034105701A / 20 / ? / 81

If anyone sees any errors, let me know.

Alan
'83 CGT 20vt
'86 4kcsq
'90 V8q


----Original Message----
Yup, I'd imagine that in order to fit 2 more valves into a combustion
chamber, you might have to make it a bit bigger, and/or dish the pistons a
bit more. However, to drop the CR from 10:1 to 7:1 you'd have to add almost
26cc to the volume. That's a 50% increase! That seems _highly_ unlikely.

On the same topic, has anyone found a site that has all the various piston
dimensions, combustion chamber volumes, pin heights, rod lengths,..... for
I-5 Audi motors? It would make these (entertaining) theoretical debates more
factual.

Cheers,
Brady



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