[Es2] 3B vs. AAN

desmo888 at comcast.net desmo888 at comcast.net
Wed Feb 18 13:27:09 EST 2004

Oh Steve, what do you know?  Just because you did a few times you think you know it all?  ;-)

Sorry for the bad info Pat.  I am doing a 3B swap and I thought the AAN swap was similar to the ABY swap.  I know the ABY has the coil pack ignition but this is upgrade with the intake has been done by 3B guys do without much problem.

I assumed the AAN swap would be similar to an ABY swap.  The ABY swap should be relatively easy as all parts can be purchased.  I guess the AAN is a whole different ball park.

Dave K.
> 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
> 3B?
> 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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> > >>
> > >
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