I have an idea about using an vr5 engine instead of the usual 1.8t engine in a4 b5 quattro's. And then of course turbocharge the vr5 engine.

Why? You ask.

Because an Audi should have an 5 pot turbo engine. Because the swap is rather unusual.
And because I think I can keep an very high OEM look under the bonnet, thanks to a lot of stuff seems rather plug 'n play. (Hopefully)

The vr5 engine comes from the vw Passat 4-motion that uses the same drivetrain as a4 quattro. The difference is the oem adapter plate that you must have between the engine block and gearbox.

If you look under the hood of an Passat it is very similar to the look of an a4 b5 1.8t.

The vr5 20v has engine code AZX and have DBW and that makes me think that the engine uses motronic 7.x ECU.
So maybe in some smart way you could modify the vr5 ecu or the a4 1.8t ecu so you can run the vr5 engine with a turbo setup.

But I need to do some deep research to figure out how much of the hardware and software that is plug 'n play or at least almost plug 'n play.
The electrical wiring is one of those things that need some research.

Why not just turbocharge the Passat vr5 4-motion?
Nah, I don't like the look of the Passat's body.

Maybe someone here on this forum knows a little more about which version of motronic the vr5 20v engine have?
And if it is possible to modify the vr5 ecu or a4 1.8t ecu so I can run the vr5 engine, and with a turbocharger also.