20V head questions

[mlp]

Richard -

20v Turbo heads (AAN) use 32mm Intake, 28mm exhaust valves.
The AAN Exhaust valves are sodium filled.

The AAN head DOES have provisioning for installation of a distributor,
its just usually capped off.  I say usually, as I had (have)
very, very early AAN crate motor which seem to have come with
a distributor installed.  I know some will say that can't, or
shouldn't be true, but the block was stamped "AAN" & there
was a distributor on the head which was removed.

Somewhere around here I had notes on the chamber volumes when the head was
cc'd,
but I can't seem to locate them.

IIRC, and perhaps someone else will have better data, I think the stock
chambers were something like about 41 to 42 cc's in the AAN heads.

I don't know how many, if any, other subtle differences there might be
between the various 5 cylinder heads.  I say "subtle" differences because
I've been told, for example, while one might think the new RS4 twin turbo
2.7 liter V6 engine is/has to be a "lot like" the S4tt, just on steroids,
apparently the head on that engine, while in might look a lot like a regular
30v tt head, is extensively reworked for the car by Cosworth for Audi ~
including reworking some of the cooling channels, and other items etc.

mlp



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Message: 11
From: "Richard Hoffman" <billzcat1 at hotmail.com>
To: quattro at audifans.com
Subject: 20V head questions
Date: Tue, 02 Jul 2002 01:21:01 -0700

Just wondering if there are any significant differences in head design
between the 20v N/A head and the 20v turbo head....obviously they will use
different cams and some 20vt heads (AAN) will not have provision for a
distributor.  Looking for thoughts on valve size/construction, head volume.
For the record, I know the 20v N/A head has sodium filled exhaust valves,
I'm assuming the 20vt heads do as well...but are they smaller to enhance
durability?  I imagine the 20vt heads have a larger valve seat/smaller ports
as well; Again to help thermal conductivity/durability.
Any thoughts?
Thanks in advance,
Richard
1990 CQ 203K up late asking silly questions