[Es2] 3B vs. AAN

Patrick Yam pkyam at bitstream.net
Wed Feb 18 11:49:03 EST 2004

Wow Steve, thank you very much for all the info and experience. I know these
messages take up time and I appreciate your efforts.

So, let's say I get a 3B motor and plan for a complete rebuild. Am I able to
use the AAN internals to rebuild the motor in the 3B block?

What parts could significantly improve the internal engine mechanics of the

Thanks, Pat

----- Original Message ----- 
From: "Steve Eiche" <seiche at shadetreesoftware.com>
To: <desmo888 at comcast.net>
Cc: "Patrick Yam" <pkyam at bitstream.net>; <es2 at audifans.com>
Sent: Wednesday, February 18, 2004 11:43 AM
Subject: Re: [Es2] 3B vs. AAN

> Dave,
> I would not agree with this at all.  I assume that you are looking to
> put a 20V into a B2 (4kq, ur q) or B3 (CQ or 80/90q), using a 3B from a
> '91 200q, or AAN from a '92-95 S4/S6.  I done or helped with conversions
> on both types on six different cars, from purely stock 20Vts to full
> race setups.  From a performance standpoint, the AAN has greater
> potential right out of the box.  It already has the better bearings, a
> stouter block (little known fact), and the more advance engine
> management system than the 3B.   If you plan on a performance rebuild of
> the engine (most of these have pretty high mileage now, so it's not a
> bad idea) and replacing the rods and bearings, etc., the only advantage
> the AAN will have mechanically is the slightly better block, and perhaps
> the nicer timing belt tensioning system.  There are 20Vt engines out
> there running over 500hp WITH distributors (though not with Motronic
> injection), so I wouldn't say that the distributor is necessarily the
> limiting factor, unless you stay with Motronic, which most of us would do.
> The AAN will cost alot more to convert to fit in an early car.  First
> off you have the intake manifold which will interfere with the radiator
> in the side mount radiator cars, necessitating the change to late S2
> (ABY) or RS2 (ADU) intake, or one of the aftermarketing intakes, like
> the Wagner Tuning or MTM intakes.  These intakes also require a
> different fuel rail, as the AAN rail in not compatible.  Then  you have
> the plumbing from the intake to the intercooler.  If you use the ABY or
> ADU manifolds, you will need the matching tubes or fabricate your own.
> The Wagner Tuning manifold requires lots of tweaks, like
> drilling/tapping the fuel rail bosses, welding on a throttle cable
> bracket, etc.  It also has no provision for an ISV, so you will need to
> add the port somehow if you want idle control.  With any of the
> manifolds, you will need to lengthen/modify the TPS and IAT sensor
> wiring to fit the new TB location if you use the AAN harness.
> Next is the water manifold on the head.  The AAN water manifold has the
> fittings designed for the front mount radiator, and is not easily
> modified to work on a side mount rad.  This means that you need the
> 3B/ABY/ADU/RR (20V ur q) water manifold.
> Accessory belt.  The AAN uses a serpentine belt setup.  This is not
> easily adapted to the early cars, mostly because of the accessories, so
> most people convert the crank pulley to a V belt setup.
> Wiring.  The AAN harness is very different in layout than the 3B
> harness, meaning a lot more labor to get the wires where they need to
> go.  I can convert a 3B harness to be "plug and play" in about 10
> hours.  The AAN harness takes twice that time, and requires lengthening
> wires, etc., which is a real PITA.  For those that haven't done it
> before, multiply those times by four.  Having the ABY or ADU harness
> would greatly reduce the time and effort.
> Flywheel/clutch:  If you are putting the engine in a B2 car with an 016
> transmission, you need the 016 flywheel, like that of the '91 200q.  The
> ur qs have the timing pin 2 degrees off from the later 10V turbos, so
> you really want the lighter 200q flywheel.  If you are using an 01A
> (CQ/80/90q) transmission, you can use the stock flywheel from the car or
> the S4/S6 dual mass flywheel with the appropriate clutch.   The timing
> pins are in the right place on any of the later flywheels, so you do not
> have to worry about that.
> What would I recommend?  If you want an AAN in your car, try REALLY hard
> to find ADU or ABY parts (water and intake manifolds, harness, plumbing,
> etc.)  used in Europe.  You can find this stuff quite regularly on
> ebay.de, and many of the sellers will ship to the US.  Watch out though,
> as fraud is much more common there.  I've gotten complete junk a couple
> of times.   There are also some suppliers that commonly ship to the US
> outside of Europe if you look.  I'm not going to give away _all_ of my
> secrets here.
> There are some other "detail" issues, but that is the major stuff.
> Quick overview:
> AAN: slightly better performance with relatively simple mods, more
> money, more effort
> 3B: cheaper and easier, takes a bit more to "beef up"
> HTH!
> Steve
> desmo888 at comcast.net wrote:
> >Very little as long as you have all the elecronics and harness...
> >
> >Dave K.
> >
> >
> >>What are the main transplant issues concerning choosing 3B versus AAN?
> >>
> >>Pat
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