[20v] 7A vs 3B C/R

JShadzi at aol.com JShadzi at aol.com
Wed May 7 12:58:14 EDT 2003

Brandon, I've measured both in the past and found them to be the same, but usually a few cc variance between heads is common.  Have you pressed him on his knowledge of the piston differences?  Can he show you what he's referring too?  The only real difference between 7A and 3B heads is the water manifold configuration, cc chambers are the same, valve sizes are the same, etc, and as far as I know, the 7A even uses sodium filled valves.


> I trust you based on knowledge you've shared with the list.  So did you
>measure the chambers yourself or have somebody do it or??  The guy here is
>saying he CC's the chamber and found them to be different?  This is contrary
>to every response I got from the list, including yours.  Any further input
>is greatly appreciated as I'm in quandary.  I currently have a 7A head at
>the machinist for rebuild so I can put it on my 3B bottom end for transplant
>into an urq-but this guy has made me nervous....
>----- Original Message -----
>From: <JShadzi at aol.com>
>To: ""Brandon Rogers"" <brogers at terrix.com>; ""20V list""
><20V at audifans.com>; <200q20v at audifans.com>
>Cc: <urq at audifans.com>
>Sent: Tuesday, May 06, 2003 9:19 AM
>Subject: Re: [20v] 7A vs 3B C/R
>This is not true, the compression he is referencing is the pistons, not the
>head, both the 3B and 7A have about 37cc combustion chambers.
>>Hi guys-
>>I was talking with a local guy who is said to know a lot about Audi tuning
>etc. He said that putting a 7A head on a 3B bottom would have a higher
>compression ratio compared to normal 3B. He said it would increase from
>9.3:1 to 10.3:1. This was not my understanding. Can anybody confirm or deny?
>200q20v mailing list
>200q20v at audifans.com

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