My RS2 tribute

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.

Coooooooooool!

I found a fellow with a good bottom end out of a similar vintage S4/S6 who lived, to my great fortune, about 3 hours away from Four Ring Performance, who was willing to sell me the whole bottom end and deliver it to the shop.  FRP didn't use the rods or pistons, but he did use the block, crank, oil pump, pickup, piston squirters, and oil pan.  Did all the normal engine rebuild stuff: align honed cam and crank journals, bored the cylinders .5mm then honed to size/surface, decked the head and block, refaced the valves, replaced the seats, new retainers, springs, and keepers.

After cleaning and painting:

After decking the block:

After bore/hone:

PIstons, rings, and rods going together (wiseco pistons, manley rods, IIRC):

Then FRP put the whole bottom end together, installed the head, degree'd the cam, put timing together, and sent it to me.  I put it on a Hazard Fraught engine stand that barely took the weight and started building it in my shop:

Jehannum said:

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.

In reply to Jehannum :

Nice to see more Audi 5cyl guys over here! That FRP engine is a work of art, and is that a Z32 TT in the background? Looking forward to following along!

Yeah, I curate a wide variety of old slow cars.  Currently: '67 GTO, '69 Datsun 1600 roadster (kiddo's project), '71 240Z, '84 Eldorado Convertible, '92 300ZX, '95 Audi S6, '15 VW GTI (kids' car), and '17 VW Alltrack (wife's car, starts most days).

After getting the engine back, I got super busy, as I volunteer to coach a summer league swim team and was sort of unceremoneously thrust into the head coach position.  Then I got a stage 2 melanoma on my neck that was able to be surgically removed.

In the meantime, I spent several thousand dollars on parts: an ECUMaster EMU Black, 5x Injector Dynamics 1300XDS injectors, a Garrett G25-660 turbo, a stainless steel waterjet cut KKK flange (stock turbo flange for the Audi platforms of that age), a bunch of stainless pipes, V-band flanges, etc.

The EMU Black came with a big jumper harness for plug and play operation that I, naturally, de-pinned to allow me to put in the wideband, flex fuel sensor, oil pressure sender (safety 3rd!), and aux fan triggers (stock it'll start low speed operation at 95°C and high speed at 105°C, and I wanted to be able to program it myself instead of relying on Audi's set points).

Then I fit up the injectors with some new billet bungs from EFI express.

Then I checked the footment on the fuel rail.

With the joy of blazing your own trails, comes the pain of finding your own solutions.

In this case, it was fitting a modern turbo designed in the last 5 years to a manifold with a flange for a KKK turbo designed in or around WWII.

Started with a water-jet cut KKK flange:

Then, I fired up my pre-war Atlas Craftsman to make it fit my 2" pipe that fit inside the V-band flange for the turbine inlet:

I left a bit of tube on it so that I could find the closest fit I could without interfering with the nuts.

et voila: one turbski attached to the manifold via KKK to V-band adapter.

I also employed a local brake/aeroquip manufacturer to me (Action Hose) to take my old feed/drain lines on the turbo, cut the hard bent tubes off 'em, and put the appropriate ends on (-4AN for oil feed, -10AN for oil drain, -6AN for water feed and return).  They also made some PTFE lines to replace the original rubber.  And they brazed some -6AN bungs onto my fuel rails so I could mount the flex fuel sensor, and adapted the new braided lines to the original inverted flare fittings on the existing hardlines in the engine bay:

So with all this in hand:

It was time to stick it in.

Well, at the very least, at that point (early this spring), it was ready to test-fit in the engine bay.

Wow, you broke an AAN bottom end, with just RS2 stuff.  How'd you manage that?  Those blocks are insanely strong.  Following this, I love the UrS6 wagons, had a 92 UrS4 for awhile that was all RS2'd

I reckon 308,000 miles at 30PSI is a reasonable lifespan.

After all that attention to the engine, I had to address an issue I had with the transmission. Some brilliant previous owner had put a stainless bolt into the aluminum case to hold the slave cylinder on and then not put any anti-seize on it. I had to replace the slave some years ago, and had sheared the bolt off in the housing. Normally this isn't a big issue, because external slave cylinders are usually mounted on the bottom where you're able to access them, but on Audi/VW 01E transmissions, they're on top, nearly completely inaccessible. There's even a special VW tool that's basically an 11mm socket that's about 8" long that fits over the bleed nipple and allows you to get at it without mangling your digits.

All of that is to say, I made a complete hash of blind right-angle drilling the sheared bolt out, and I'd gotten by with a semi-floating 13mm shoved in the hole with a couple metal zip ties around the case holding the slave cylinder down. Nothing's more permanent than a temporary fix that works, after all.

So, I extracted the transmission, had a local machine shop do their business, fill in the hole that I butchered, then stuck a new slave cylinder on (because I was replacing the clutch anyway, might as well do the whole job from soup to nuts).

The offending bolt is there in the middle of the picture, underneath the slave cylinder.

I also washed the hell out of the engine bay, because the exploding engine had left a lot of goo, everywhere.  Purple Zep and a pressure washer FTW.

Then I found out that the gaskets cross listed for my Audi don't actually fit. They fit later versions of the 01E, but not this one, for some reason, so I got to make some using my Cricut.

And to make things easier on me later, I added a remote bleeder. Probably use it about once in the rest of my life, but whatever. It's there now. It's attached via a -3AN hose down to a 10mm x 1.0mm inverted flare fitting to -3AN adapter on the slave cylinder. 

While I was recovering from having my neck carved up, I'd made the breakout harness for the extra stuff I wanted to put on the engine (ethanol content sensor, oil pressure sensor, wideband O2).  To make the new ECU work its absolute hardest, I needed to make an engine bay harness and get those things run out to where the sensors lived. I'm not a "let's hack up this perfectly working 30 year old harness and see what we can stick where" kind of guy, so I made a subharness that runs out a new hole in the floor through a waterproof grommet.

First, I abused my step bit to go through a bunch of asphalt sound deadening and into the engine bay.

Then I pulled way too much wire through, because I probably had about 4 feet of extra length just to make sure everything got to where it needed to be. I found some nice "painless" braided sheathing that fit in nicely with everything else.

Then because it's a German car, I put Deutsch connectors on, which sounds kind of like "Germany" in German. It's also what I had on hand, and they're really nice to work with. Besides, the O2 sensor kit came from the vendor with one.

Then I got the stock ECU box to go back into its stock location (over the hole I'd just drilled), and mounted the ECU way at the top to avoid any water leakage that tends to happen there in these cars. The jumper box/PNP harness is mounted below in the stock location of the ECU. The other stuff is just original wiring or extra length (on the vendor-supplied O2 sensor harness).

Then I closed everything back up so that the carpet can go back over 'er and ran the USB tuning cable out the same hole the engine bay harness goes in.

And finally the payoff (you may now hum "Deutschland über alles"):

Of course, that's all kind of burying the lede, which is that things feel much more rewarding when heavier chunks come together.

So, I hung the motor, put on the new clutch (Southbend, stg 4), and started checking fit by dipping it in the engine bay. It turns out I had some work to do, so I got my die grinder and removed a little bit of the unibody around the turbo oil drain (because hey, it's not a project until you've bashed/bled/ground the E36 M3 out of something). It has a beefy subframe on either side of my berkeleyery though, so I'm not as concerned as I probably should be. However, to minimize the amount I had to trim, I turned out some 5mm taller motor mounts from some spare aluminum stock I had on hand.
 

Plenty of clearance, right?

Then I seated 'er for well and good.

After a bit of a time jump, I got the accessory stuff reassembled, which took some thinking because it turns out my carefully planned out positioning of the oil pressure sender (aftermarket) interfered with all the things.

So after a re-think, I put a 90° 1/8 NPT to -3AN, ran a -3AN PTFE line up to where the solenoid for the evap canister used to be, and mounted the OPSU there. The broken wires in the foreground were a fun surprise for me to deal with later. They feed the exciter on the alternator and the dash coolant temp sender, and I did replace them.

Then I filled it all up with oil, coolant, mounted the accessory belt and put the front of the car back together.

With that win, it was time for a big setback, when I realized that the seal separating the HVAC plenum from the interior was in a somewhat deteriorated state. Normally not a big issue, but with the car stored at a jaunty rake like that on the ramps, well, things got to be an issue. It first manifested as the alarm going off once every hour, and randomly locking and unlocking the doors (which these cars do with a vacuum pump, because electric actuators were too expensive in 1995).

This is underneath the back seat, where the battery lives on these cars. At the bottom of the picture is a foam enclosure for the central locking/alarm system.

So I did what any good German car owner would, and threw the central locking computer into some rice for a few days and then hosed it down with Corrosion X.

Except for the immobilizer (which is, conveniently, controlled by a single relay under the dash), it works perfectly now. I jumped the relay for the immobilizer, so meh. It's just a normally open relay that keeps voltage from reaching the starting solenoid, which I noticed because when I went to prime the oil system (plugs out, watch the oil pressure, crank the car over), it didn't.

However, after jumping the relay and then a new starter, eventually the priming went ahead, which lead eventually to this:

It was a very rough street tune that more or less kept lambdas somewhere nice, and limited boost to 5 PSI.

My punch list after the street tune was:
1) pull pin 41 from the Motronic connector to black 10 on the ECU Master Black, because while their "plug and play" adapter had provisions for powering the AC clutch, it had no provision for reading whether the AC had been demanded by the climate control.

2) pull an aux output into the engine bay to trigger a relay for electric fans. The original clutch fan itself broke while driving, and at that time I couldn't source a replacement.

Busted fan:

(so that's why it was making clackety noises)

Fortunately, a neighbor had a 32/36mm fan clutch wrench for his kid's BMW and between that and my death wheel's spanner wrench, I was good to go.  This was kind of lucky, as they don't often come off cleanly.

New fan

Pulled power from the aux fan as a trigger for a solid state relay:

This was well and good until the summer got into full swing, but it did carry me through break-in mileage.

Very nice!  I've always been more of a 10VT guy, but I do love the UrS avant.  Happy to see you are doing better, and the car is coming together!  Keep up the good work.

During break-in, I went ahead and added a bluetooth module to the ECU so that I could stream the data that I don't have on the dash to give me warm and fuzzies on my phone and/or tablet.

I also ran into a weird miss around 4K RPM, which I initially attributed to it being a weird 5 cylinder and not properly supported by the ECU, but then I found some real pro-level aftermarket wiring, which reminded me why I don't mess around with anyone but Wiring Specialties or myself.

So I rolled my own ignition subharness, but instead of sticking the coils on the same 15A circuit as the ECU, I ran them off the remaining channels on the solid state relay (for 20A apiece, one for 3 coils, one for 2).  These plugs are back sealed in the cavities, instead of relying on the accordions.  Cleared that misfire right up.  I believe this is also the point at which I ordered genuine article Bosch red-top coil packs to replace the Densos I had before.

Oh, and I added a genuine Lamborghini oil cap.  +10HP.

So once it was mechanically sound, I decided to polish the turd a bit.  It had 300k miles of rock chips on the front, after all.

I also hit a deer and had mangled the bumper in like 2022.  I fixed it, badly, but then came across a new bumper (finished in emerald green, naturally) in Ft. Collins.  So, I bought it, threw it in the back seat of my wife's VW Alltrack (we were up in Denver for a Tool show in Loveland), then threw it in the back yard to wait for me to get my poop in a group.

I also had the spoiler re-done, as it had some bubbled spots too.

They did an acceptable job color matching the pearl (Audi calls it "Magnolia Yellow", and it's yellow next to white cars, but white next to yellow cars).

The bumper was originally secured to the crash bar with some aluminum rivets on the bottom (and those weird plastic tabs on the top, which I miraculously didn't break removing the old bumper for paint).  I elected to replace them with rivnuts for some M4 hardware.

The hardware is stainless with fender washers, and some rubber gubbins underneath to keep it from marring the bumper on install.

Almost feelin' good about the outside here:

The next jobs were: refinishing the wheels, an alignment, and a dyno tune on pump gas.

Lucky score on the bumper!  They've been NLA for years

In reply to docwyte :

Yeah, it had some issues, but some heat and gentle persuasion (e.g. leaving it in the sun on sawhorses like I didn't give a crap about it) finessed it back to shape.

I also had to fix a few broken pieces of plastic threaded nonsense on the trim, which I did using some stainless socket head screws countersunk into the original plastic and then superglued down:

The other side came out unscathed, but I need to keep my eye on it anyway, since it's plastic and this is the desert:

So that got the last of the outside of it together.

I powdercoated the BBS RG wheels (stock Audi V8 Quattro wheels, 16x7) "Silver Ore", a nice single-coat powder from Prismatic Powders, and then got completely the wrong size tires put onto it (apparently I can't read the difference between 50 and 60).  I resigned myself to rubbing and nonsense for a while, but at least they were just cheap uniroyals that I didn't really care about.

Now, the $200 lesson I taught myself about alignment: just go through the whole thing before you turn it over to 'em.  I got the car back from the alignment shop and they gave me the bad news: stock alignment was unachievable, because I hadn't installed the front offset caster bushes correctly, and the rear was unachievable because the lower control arm bushes were shot.  Also, the front struts were just pouring oil all over.  They're Koni Sports, so I called and got another set off the shelf, and started taking the old strut housings apart to replace them, when I saw that the spring perch had wallowed the center hole out a whole hell of a long way.  I took my welder and un-wallowed the hole:

Then I chucked it up in the lathe and bored it to size.

Reassembled them and gave them a good krylon restoration (with new struts, strut boots, and bump stops):

Then I put them back in the car:

The rear was in good enough shape that I figured I had time to focus on other stuff until it got less gross outside.  The fronts run Audi A8 rotors (312mm) and Porsche boxster (base 1997-2004) calipers on some Apikol caliper spacers.

The reason why the caster was all out of whack on the front is because I don't run the stock strut bearings.  For one, they're made out of origami, and for two, the aftermarket ones all have terrible rubber, and when they fail, the top of the strut pops through and punches the hood.  So, I use some pillowball upper mounts that the designer didn't quite think all the way through, so they raise the car about half an inch, and that makes the stock geometry all berkeleyy (either you get a ton of negative camber or a ton of positive caster; I opted for the caster, which I think is what blew my struts up):

Finally, I ran it by my tuner, who was excited to get his hands back on the car (he was the one who street tuned it after the initial start).

It made 398HP at 25PSI of boost before hitting the boost cut up top, then we cut it back to 389HP at 20PSI for the street, since this is supposed to be the safe, 91 octane tune.

It's a hoot to drive, but the fun of the spring giving way to summer meant I put it on the shelf for the most part, because 1) that electric fan isn't adequate in 110°F heat, and 2) I promised my kid that we'd get the 1600 roadster started again and 3) I had to devote a ton of attention to running a swim team.

With any big German estate car, half the pleasure in driving comes from the the creature comforts.  Pulling the engine had damaged some of the AC hoses, which I had remade, however that left me with the small issue of charging the thing with refrigerant.  It's an early R134a system, but only included the standard high side fitting.

The low-side AC fitting, however, is an M12-1.5 pipe fitting. Unsurprisingly, there aren't many cheap options out there to turn that into an R134A service port, so I grabbed one from the FLAPS (a standard 7/16-20 service port conversion for an R12 to R134A system), then fired up the lathe to make an adapter for my adapter. :xzibit:

The outside (7/16-20) I single-point threaded on the machine. The inside is M12-1.5, and I had no threading tool that would fit inside a hole that small, so I did it with a thread cutting tap and followed it up with a bottoming tap.

I picked the right length, then parted off the 7/16-20, chamfered the edges (because that's what separates us from the animals, after all), and installed my adapter to my adapter.

Then installed the adapter on the adapter on the low-side port, vacuumed and charged the system, and returned to bathing in glorious, cold AC.

Before you ask, yes, I know there's a McMaster part for this, but I priced it (at the time) at $55, which isn't unreasonable, but I can use the practice on the lathe, and this was substantially cheaper if my labor cost is $0 (which it really should be, I'm no great talent there).

And to go along with the "creature comforts" being addressed while the car was down for the summer, I had the disintegrating parts of the passenger's seat reupholstered.  I'm both thrilled and appalled. The leather work made the rest of the car look pretty worn.

I have to say, after a few months, I barely notice.

I had the driver's seat done by fibrenew in 2022, and it was a lot more in line with my notion of a sympathetic restoration.

Come the end of the summer, Vemo ran another production of the plastic clutch fan!

So, I needed to undo the cut I took to get rid of the M24x1.5 mount to clear the electric fan.

Took some 1" round bar down to make a mandrel for my M24 die.

It fits!  I needed the length, because I couldn't get the die to thread on straight, so I figured a bit of sacrificial length to act as a guide would be a reasonable compromise.  Again, I'm aware that there are ways of getting my SAE lathe to cut metric threads, but after trying some scratch passes with the cheat sheet, I still couldn't get anywhere near the threads I needed, and Amazon sent me the die overnight, so...

Made it threaded:

Then I threaded the inside (because that's the retention method for holding the whole thing in the bearing):

Finally, I chucked up the remainder of the idler in the 3-jaw, screwed the retaining M8 through the back of it, and welded them together.  Had about .002" of runout, which is acceptable:

Then I parted it off, installed it, and started enjoying sub-210°F coolant temperatures.

safety sandals please but LOL

and NICE job!

The last thing on the punch list before a self-imposed deadline of 27 September (when I'm heading up to southern Colorado to bomb around some mountain roads) was to get the suspension right (or right enough).

I turned the caster bushes around in front, which allowed the alignment shop to get to a good factory caster setting of 1°, as well as dialing in -2° of camber.

Then I started on the rear.  The shop I use for alignment previously told me that the lower control arms' inner bushings were toast.  In my vast box of spares, I had pretty much a full set of AK Motorsports (now "Verkline") polyurethane bushings, so I pulled those out of the attic, and got to work.

I went back around and cleaned up the burnt rubber that my boy left all over the driveway with the pressure washer, since he couldn't be bothered to do it in the rocks. I must learn to be more specific when I give him instructions.  Here we're burning out some old bushings:

New bushings installed:

Installing at full droop was... challenging.  I expect that if the car spent a significant amount of time at full droop, these bushings would get tore up in a hurry.  After the driver side, I figured out it was easier to get the front and two knuckles bolted up loosely, then to use my jack and rotate the rear into place.  If I were building a race car, I'd probably hack off the bushing mount, weld in a threaded insert, and put a 12mm spherical joint there instead.  I'm going to see how these wear over the next few months though, and see how it goes.

Now featuring correct-sized shoes (225/50-16 instead of 225/60-16), an alignment that's more to my liking (not 4° of positive caster for ultimate numbness in steering somehow combined with high speed jitteriness), and bushings that aren't crumbling into dust:

I also added IMPORTANT modifications:

That brings us up to current. 

I'm waiting on Summit to ship me a set of rear strut bearings so that I can put new Konis in the back, and on steve_3b to get his poop in a group so that we can do a twofer of a pump tune on his 200 quattro and the e85 tune on the wagon (also waiting for some cooler weather, because the local 4 wheel dyno is just a shed with a swamp cooler).  Finally, deciding when to take another bite at the apple and drive it out to another Radwood event (probably Austin, since I have family there).

Love the color and thanks for sharing. 

fidelity101 said:

safety sandals please but LOL

 

and NICE job!

I hate shoes.  But yeah, if I'm on the lathe, working with the plasma cutter, or welding, I'll wear them.

Where are you driving around in Southern CO at the end of the month?  I like driving around in Southern CO....