Engine swap in '96 A6: AAN instead of AAH

[OrMar]

So, I have '96 A6 (C4) avant quattro with 2.8 AAH engine (174hp) and would like to put in engine and gearbox from an '93 S4 (AAN).
What parts do I need (except engine, gearbox, harness, ECU) ?
What problems should I expect ?
Any link of someone doing the same ?

Thank you,
Mario

[S2central.net]

I'm not the C4 expert, but you need to check if the engine mounts and subframe need to be modified or changed as part of this...

DUnno if the AAH engined car has 01E gearbox or not - if so you could just use it. When swapping gearboxes you need to be certain that final drive ratios are matched front and rear.

You may need a different/better clutch than what is there on AAH setup.

You will need AAN airbox, intake pipework and the small matter of an intercooler to complete the conversion... Look here and elsewhere for front mounted intercooler (FMIC) upgrades on the UrS4/S6 - the factory setup is far from ideal.

The wiring loom & ECU swap is going to be the most daunting task unless you are well experienced on electrics, but myself and others can keep you right if help is required there.

DUnno if AAH fuel pump is different from AAN - worth checking that.

[OrMar]

That was quick, thank you!
If everything goes as planned, I will have both complete cars side by side, so availability of parts shouldn't be a problem. However, I would still like to know what is necesarry to swap, and what isn't.
Just crossed my mind: what about key codes ?
Also, after close examination it has come to my attention that I don't have button to lock rear differential in my A6; does that mean that diffs are different ?
Mario

[S2central.net]

They did delete the rear diff lock cancel option at some point - cant remember when. Shouldn't be a problem to move lockable diff onto the 'new' car.

I can help you get immo/key codes swapped when the time arrives if necessary - in private of course

I can also help you get another 40-50bhp on that AAN engine with some new software if you like - all in good time !!!!

[Nace20]

They deleted the button with model change
audi 100 C4 had button
audi A6 C4 didn't, but had EDS

for motor mounts, you have no problem, just have to change them, if you have whole car, there is no problem.