Backstory: in 2018, my daily driver, a 1990 Cadillac Brougham, was stolen out of my driveway. It had no real value as it had spent 20 years in Wisconsin, so it was mostly just structural rust under a thin skin of bubbling paint. I subsisted using my project cars for a few months, until my friend steve_3b made weird noises about dumping all of his ICE cars for one or more Teslas (early 2019).
In his stable was a '95 Audi S6 Avant. It'd had some work done, and had a history in the community as a "RS2'd", where the owner will take genuine article RS2 pieces (usually cams, fuel injectors, turbo, exhaust manifold) and bolt them to the AAN or 3B motor in the C3/C4 24V 5 cylinder chassis they've managed to get hands on. I raised my hand (and my money) and bought it, at 280k miles with all the RS2 bits, an "intended acceleration" tune, and a set of Audi 7A (higher lift, longer duration than RS2 or stock AAN cams, originally sold for a higher compression 20V 5 cylinder with no turbo).
I suspected on test drive that it made horsepower in the low 300s. I proved it out later:
Now, I'll fast forward a bit. I did some maintenance, which included replacing a bunch of bushings, a head gasket, some control arms, a clutch pedal (or three, stiffer clutches tend to break the cast aluminum pedals, so I have a stock of them that I have TIG welded back together, and 3D printed new mount bushings for), and a set of BBS RG wheels off of a V8 Quattro. In general, I was a happy man, and the car was very well received at Radwood. I even took it autocrossing a few times (it's not competitive, and I'm not great at driving it fast, my 240Z is a much better, more rewarding drive in that venue even though it's about 1/2 the horsepower).
That is, I was a happy guy, right until May 2023, when I was making a slight left out of Lampasas, TX, on my way home from Radwood Austin and visiting family (with my family in the car), when #3 rod exited the chat and broke holes in both sides of the motor.
As she sat in Austin:
The carnage:
So, I did the right thing, and instead of throwing the car out, I called Jeff Gerner at Four Ring Performance, and started the wheels turning to build a new AAN motor. Fortunately, (or not, IDK, I'm not a smart man) the head, manifolds, and basically everything but the block, crank, #3 rod, #3 piston, the oil pan, and the oil pickup were salvageable. That's not to say I used any of it, but I did reuse the head as they're somewhat difficult to come by.
At that point (early June 2023), I started making plans. First, I wanted an engine management system that would play nice with Audi's stupid 3-sensor Monty (cam 0, crank 0, and 135 triggers read off the flywheel) along with flex fuel from 0-85% ethanol with wideband feedback , second, I wanted turbo and fueling that was new, not the old K24-7200 and Bosch fuel injectors that needed 28PSI and 95%+ duty cycle to make 325HP. So, I had my work cut out for me.