I found a shortcut to carbon clean an APR-supercharged S5, RS4, or R8 in just 2.5 hrs

[volvofan]

I'm at 85k miles and am staring down the barrel of a carbon clean (last done at 48k by the previous owner). When I started to think about what's involved in pulling the supercharger myself to do it, or paying well over $1k to have an APR-certified shop do it, I started to mull over some alternative approaches. Say what you will about their discontinued Stage III or Stage III+ product, the fact of the matter is, there are hundreds of APR kits out there (for better or worse) and one of them happens to be bolted under my hood, so even if it wouldn't have been my first choice if I were doing the mods myself (I bought my 2011 S5 this way, it's a Stage III), I've got this egg to suck now. BTW, this isn't me knocking on APR... I think it's an amazing package and even if it seems like the tune is a little rough in spots, it's predictable (i.e. off idle, or shifting 1-2 or 2-3), and only seems to be an issue in "comfort" or "auto" mode. When I've got it in dynamic and I'm romping on it, this car is a f**king velvet cruise missile that just wants to pull hard ALL. DAY. LONG. I'm sure there are others out there who feel the same way and who have this kit on their car, so maybe this will interest and/or help them.

The good news is, because of the unique design of the supercharger manifold and where the intercoolers mount, the setup lends itself to a potentially VERY easy carbon clean technique that can't really be employed on any other naturally-aspirated or forced-induction Audi platforms of which I am aware. I say "potentially" because it will involve putting your car irreversably "under the knife," so the setup for this procedure is not for the faint of heart. I haven't tackled this project all the way through YET, but will post pics and a thorough walk-through when I do. I figure even if I do the carbon clean myself three times on the car, I've saved well more than the time and money invested in developing this solution. Once I do some one-time setup work (i.e. notching the radiator shroud, drilling & tapping the plugs in the top of the SC manifold), the "major muscle movements" involved in a typical carbon cleaning henceforth should look something like this: (EDITED this list based on what I ACTUALLY found when doing the process)

PHASE 1 - PREPARATION (1 hour total)
1) Remove the slam panel (and cutout cover/reinforcing plate, if you made/installed one) & clamp the low pressure fuel pump line; crank until car no longer starts (15 mins)
2) Remove the intercoolers and clamp off hoses or reinstall hoses on IC while OUTSIDE of the SC manifold... the coolant pump kicks on when you crank the car, and you don't want a shower! (20 mins)
3) Remove the set screws in the top of the manifold (5 mins)
4) Spray Carb/choke cleaner or something else to soften up the gunk via the removed set screws in the top of the manifold (5 mins)
5) Identify which side has all the intake valves fully closed. Crank engine over again if needed, as you may find partially open valves on both sides (5 mins)
6) Set up your walnut shell blaster, shop vac, and air compressor (10 mins)

PHASE 2 - CLEANING (2 hours total)
7) SOMEHOW (TBD) plug gap along supercharger outlet side of manifolds to prevent dust/walnut shells from reaching the screws (5 mins)
8) Tape inlet screen (green scrubby pad) on the firewall-side intercooler hole to keep any stray shells from coming out the back, and tape shop vac on the grille-side intercooler hole (5 mins)
9) Set up walnut shell blaster, turn on shop vac, and blast the four cylinders with closed valves (tape closed the holes you're not using on that side, 30 mins)
10) Blow out / vacuum out all remaining walnut shell residue. Verify with borescope (10 mins)
11) Remove plug from supercharger outlet gap and green scrubby pad (5 mins)
12) Crank the car over until the other bank has all cylinders closed. Verify with carb/choke cleaner if necessary; look for pooling around valve seats (5 mins)
13) Empty shop vac and refill walnut shell blaster (5 mins)
14) Repeat steps 6-11 on second cylinder bank (55 mins)

PHASE 3 - REASSEMBLY
15) Reinstall set screws on top of manifold; use appropriate sealant... if you use water/meth, remember that teflon doesn't like methanol! (10 mins)
16) Reinstall intercoolers and top up coolant (20 mins)
17) Remove fuel hose clamp, reinstall slam panel, and reinstall reinforcing/cover plate (15 mins)
18) Clean up tools, shop vac, and walnut shell blaster (15 mins)
19) Crack a cold one and post up on AZ how you got a carbon cleaning done in less than 4 hrs flat using this technique (priceless)




TOOLS I WILL NEED:
--Walnut shell blaster, with long nozzle (at least 14" or so). The 20 lb pressurized one from Harbor Freight is perfect. I then bought the Bavarian Autosport 90 degree blasting nozzle (which is really just some bent brake line tubing and a couple brass fittings preinstalled). I think in retrospect I should have gotten the straight one, as the 90 degree one goes in almost all the way to the bend. I spent about $75 or so in total.
--Borescope. You'll want this to inspect the valves to see which ones are closed, whether the carb/choke cleaner is pooling up in the port (to confirm they're closed), and to inspect your work after blasting. $25 or so on eBay for a wireless one... very cool.
--Grabber and long pry/push tools. Need these to get the supercharger outlet manifold plug into position.
--T30 Torx
--#2 Phillips
--Shop Vac
--SKINNY adjustable wrench or 13/16" open-end wrench (so you can loosen/rotate the back left intercooler pipe elbow, I found a nice vintage 13/16" open end for $9 on eBay)
**The wrench MUST be thin... you have to be able to turn the jam nut without having the wrench jaws interfere with the fitting itself. Needs to be about 3/16" thick maximum.
--Rags/towels (to wrap the intercoolers in once they're deinstalled so you can rest them safely on top of the SC manifold or wherever)
--1/8" tap, "Q" drill bit (to drill & tap the holes in the top of the supercharger manifold)
--(RECOMMENDED) drill guide to ensure you drill a perpendicular hole in the top of your nice pretty supercharger manifold
--Cutoff wheel and file (to notch the radiator support so you can get the intercoolers out on certain models)
--Hose pliers (to pinch off the intercooler lines while you have the ICs disconnected)
--Appropriately-sized hex key for the set screws







PARTS I WILL NEED:
--Walnut shell blasting media (duh)
--Tape (duct or masking)
--A "green scrubby" pad or other suitable open-cell foam to allow make-up air into the SC manifold
--1/2" ID caps (or plugs) x4 to allow you to remove the intercoolers without spilling coolant everywhere
--8x 1/8" NPT black anodized hex set screws and suitable thread sealant (yes, I know that NPT plugs aren't really 'set screws', but I was already using the term "plug" elsewhere in this DIY and wanted to disambiguate)
--A pair of "drop stops" - neoprene closed-cell foam "as seen on TV" thingamajigs to keep stuff from falling into the gap between your center console and your seats)
--(OPTIONAL) 1.25" x 1/8" x 2' long aluminum flat stock and mounting hardware IF you want to reinforce the radiator support after you notch it

SETUP:
1) If you have an S5 (and probably an RS4, from what I've seen online), the supercharger intercoolers sit just below the "high water mark" on the radiator mounting assembly, so you'll have to put a couple notches in them in order to be able to get the ICs out of the supercharger manifold without removing the manifold itself. This took me about two hours with a cutoff wheel and file.
2) Obviously, once you have the ICs out, you'll have to stick something in the cavity to block the ports while you CAREFULLY mark out, drill, and tap the holes for the plugs that will allow you to perform your laparoscopic surgery. I'm going to go about an inch to an inch and a half away from the leading edge of the manifold. I estimate this will take me at least a couple hours.
3) IF you wish to do so, you can reinfore the radiator mounting assembly with the 1/8" thick aluminum bar stock and suitable mounting hardware (sheet metal screws?) to make up for the notches you made. I have not done this yet, but I do plan to.
Clearly you will NOT want to use rivets to hold it in place, unless you want to drill them out every time! I figure another two hours of fabrication to make the brace, plus add another ten minutes or so to the actual carbon cleaning procedure to remove and reinstall. Looks really nice with matte black paint after completion.



Once the radiator support is notched and the holes are drilled/tapped/plugged, you won't have to do any of that over again, you'll just follow the procedure outlined above.

ADDED BONUS: Instead of set screws, perhaps this would be a good location to install water/meth injection nozzles? I don't really feel like I need more power, but I have often thought about tossing some suitable PEA / PBA detergent (I think Redline SL-1 is the highest concentration) into a water/meth mix to wash down the intake tract and keep carbon from building up in the first place. I think I will just use the set screws as "inspection holes" for now, to see if I feel like I can stay on top of the buildup with regular cleanings like the one described, now that it's not going to be quite such a multi-day pain in the ass.

Okay, I've got my support notched and the manifold plugs on order... more details and photos to follow once I get the rest of this job done! Stay tuned!

-Jon

[volvofan]

Really? 200 views and no comments? "Hey, what a great idea!" "You're a f**king crazy idiot!" or anything in between? See any potential problems I'm not thinking of?

-Jon

[wkhanna]

i applaud your ingenuity...

[volvofan]

Would have finished prep work this weekend but my cousin threw a rod in his Suby WRX so we spend all of Saturday giving it a heart transplant (successful, BTW). I did have enough time left today to do the radiator support reinforcement. 1/8” x 1.25” x 20” long aluminum flat stock. Cut to length, bent, then marked and drilled to ensure four holes on either side of each notch. Also bit out a chunk to enable clearance of the hood striker.

Secured with 16x 3/4” self-tapping screws, after pre-drilling holes in the aluminum.

Next step is the NPT plugs themselves.



-Jon

[S5_SID]

Love the thread!

Any way you could add pictures for a step by step. I am a virtual learner and way easier to see if I’m on the right step.

👏🏻✌🏻

[volvofan]

Thanks! Yes, I’ll definitely keep posting pics of the prep work, and will absolutely take some when I finally do the clean. May even shoot a video :)

-Jon

[S5_SID]

Thanks! Yes, I’ll definitely keep posting pics of the prep work, and will absolutely take some when I finally do the clean. May even shoot a video :)

-Jon

Awesome!!!

A video would be even better! Thanks for the post though, I’m all about finding ways of doing maintenance faster.

-Sid

[gqambitions]

Thanks for throwing this thread up. I m looking to do a carbon clean on mine with my buddy and this has given me somewhere to start I do not have a supercharger though, wondering how different the steps would be. This is my first time and any tips would be helpful. Thank you.

[volvofan]

Okay, so I finally got around to giving this a try a few weeks ago, and am just now getting around to doing the write-up and posting the pictures.

Here's the bottom line up front: IT WORKS, But............ I still haven't figured out a good way to seal off the supercharger outlet to keep walnut shells from getting back in there. Without solving that problem, you're still going to have to pull the SC off in order to do the job. With the SC removed, you're back to "square one" as though you were doing a carbon clean the "old fashioned way" as you'd do on a N/A motor.

First, you've got to kill the fuel and make sure the engine doesn't fire up when you crank it over. I tried a BUNCH of different methods... looked to pull relays in the ECU area, pull fuses, disconnect high pressure fuel pump plugs, etc... nothing was doing the trick. In the end, a simple hose clamp on the low pressure supply line starved everything out good.







Next, I set up to drill the holes for the plugs (or H2O / Meth nozzles, if you feel like getting froggy) by taping off the tops of the manifolds and using a center punch & ruler to mark where I wanted each one to go so they'd be centered over the runners.




After that, it was time to remove the intercoolers. I disconnected the front (outlet) fluid lines first and capped them off so they wouldn't spill coolant everywhere when I pulled the cores out.




On the passenger rear intercooler, you have to rotate the fluid inlet elbow in order for the intercooler to be able to pass through the manifold without catching. You need your super-thin wrench here, and oh by the way, the cap probably won't fit through so a plug (like a cork) probably would have been better (see initial "bill of materials" where I listed a cap). It's tight, but you can thread everything around the fuel lines and get it out. Loosening the fuel line bracket and/or some of the hard lines themselves MIGHT help, but it's best not to mess with any of that if you can avoid it.






Remove the retaining shim and the intercooler will slide right out, thanks to the notch you cut into the radiator support. DO NOT DROP THE SHIM.








Now to drill and tap your holes. Remember, all this one-time stuff (drilling/tapping holes, notching radiator support) will pay dividends the more times you decide you need to do a carbon cleaning, as you only have to do them once. I used an angle gauge to serve as a guide for how to hold my drill, as I wanted the ports more or less facing normal to the intercooler inlet, just in case I decide to go with a H2O / Meth setup in the future, versus simply plugging the ports. I put a towel or something inside the intercooler hole to keep shavings from falling down all the way to the valves (as I didn't know at that point which ones would be open. I also put grease on the drill bit to catch the shavings and keep what was falling in to a bare minimum. I used three different bit sizes, stepping up gradually, due to the angle at which I was drilling. I started most holes off by drilling normal to the surface, then after getting 1/8" in or so, I slowly tilted the drill to the desired angle.






Put some grease on your tap to catch the shavings, and only tap about 1/2 to 2/3 of the way down the length of the threads so you still maintain some taper in the hole. Otherwise, if you run the tap in too deep, the plugs will be able to thread all the way through and you'll have to use loctite to hold them in place. Ask me how I know.




Here's a view from the inside of the manifold. You can see the holes you've drilled/tapped are right above the runners. I used that "drop stop" to block off the passage to the right that is where the supercharger outlet was. I was a bit too cavalier about how much "blowby" I was expecting based on what I'd blocked off... this is where the wheels started to fall off the wagon on my plan. That was NOT sufficient to keep walnut shells from making their way back to the supercharger outlet, which is not somewhere you'd want a bunch of walnut shells collecting, believe me!




Blissfully ignorant, I proceeded boldly onwards anyhow. I wrapped the intercooler in a towel and set it aside (so that if the pump kicked on at random times - which it did - then it wouldn't spray coolant all over the place). You could also either clamp off the pump outlet hoses, or you could somehow plumb in an intercooler bypass length of hose if you had a couple of hose barbs & clamps. Anyways, then I went in with my endoscope to check out how much gunk I was dealing with. Having been almost 40k miles since the last cleaning, the valves were definitely due. I used the endoscope to ensure I didn't have any open valves (I also sprayed some carb/choke cleaner down into each hole and made sure it was "pooling" around the valve seats to verify they were closed). Then, I put a green scrubby over the back of the intercooler passageway to act as an inlet screen (to prevent any walnut shells from getting bounced out through there) and taped my shop vac inlet to the front intercooler passageway.





The media blaster I ultimately settled on was the cheap 20-lb one from Harbor Freight. Worked fine, although adjusting the air/media mix was a bit of a trial-and-error process. You start to get a "feel" (by sound) for how much media you're sending through the nozzle. Also, if it's got a 90-degree bend in it and you're blasting a lot of media for the given amount of air you're using, you'll actually feel the 90 degree bend start to heat up from all the friction :)




I did get some great results from the blasting process. It didn't take long to get the hang of "blast for 10-20 seconds while wiggling the nozzle around, stop, pull nozzle out and put endoscope in to check progress, repeat as necessary". The one thing you'll notice is that, since you're doing this "laparoscopically", you don't have quite as much freedom to maneuver the nozzle around (nor can you see where you're putting it, although you'll be able to feel the ridge between the two valves and use that as a guide), so there are some "blind spots" that will make carbon removal difficult. Namely, an area behind each valve stem (you can actually see a small chunk of carbon hanging on for dear life in my "clean" picture) and up high around the valve guides. Still, for the little amount of time it takes, I'll take a 95% solution that requires 2.5 hours of work versus a 100% solution that requires 12 hours!








Each time I'd blast out a cylinder, I would follow it up with blasting compressed air only (no shells) into all four cylinders on that side, with the shop vac running the whole time of course... that kept the shells from building up too much and blocking flow through the main passageway where the intercooler was. If you blast enough compressed air into each cylinder at the end, it will get all the leftover walnut shell bits out. You can also use an attachment to VACUUM through the nozzle rather than BLOW through the nozzle to get the stragglers. Once I was all done with one side, I removed the "drop stop" to find the following picture, which immediately informed me that this job was going to take a LOT longer than I'd hoped. I had to remove the whole supercharger manifold, then ALSO remove the supercharger FROM the manifold and thoroughly clean it out before reinstalling.




So, on I went to the other side. First, after ensuring that everything was cleared out and away from the intake valves (the supercharger was now completely removed), I cranked the engine until all the ports on the OTHER side were closed. Then, I taped off the cylinders I'd just cleaned. As long as I had the supercharger unbolted from the manifold, I decided to still use the "empty" manifold to keep the shells contained as I blasted, since that part was working fantastically... practically ZERO mess. I tried a couple other ways to block off the supercharger outlet (see photo below for one example) while "testing" each method by putting masking tape across the hole where the SC would have been, then looking for walnut shells stuck to the tape after blasting for a bit. A couple of my iterations (rolled up terrycloth towel with EPDM "flap" taped to it) resulted in VERY FEW shells blown by... maybe a couple dozen individual grains. STILL, that's too many for me to consider risking my engine for.



Some other later iterations showed great promise... the one I hold out the most hope for was when I used a 3/4" nap 18" long paint roller that I'd cut slots and drilled holes into. Added bonus, it was very easy to find a place to attach the shop vac hose. The next time I attempt this job, I'll probably start by trying some version of that... while also planning enough time in advance in case I need to pull the SC again.

That's enough for now... I welcome your thoughts, comments, gripes, complaints, hurt feelings, suggestions, etc.

Thanks!

-Jon

[volvofan]

Thanks for throwing this thread up. I m looking to do a carbon clean on mine with my buddy and this has given me somewhere to start I do not have a supercharger though, wondering how different the steps would be. This is my first time and any tips would be helpful. Thank you.

Steps will be COMPLETELY different. Your intake manifold is not going to look anything like the supercharged one. Just unplug everything from the intake manifold, rip that sucker off, put down a bunch of dropcloths all over your engine bay, and start walnut blasting away!!! Messy job... do it outside if you can so you don't get crap all over your garage.

-Jon

[volvofan]

A couple shots of the finished product:

[Ape Factory]

Did you use straight walnut shells or did you soak the valves in a solvent first?

[volvofan]

Sprayed some carb/choke cleaner in each runner and let soak for an hour or so, then blasted away!

[Robert7x]

If you don’t have those sea shells to clean it with... what other brushes and chemicals are giving good results? I was going to do this on my RS5 over winter.

Thanks.

[volvofan]

I used walnut shells... it's actually a bag of lizard bedding from PetSmart :)

The carbon isn't super hard, it just won't "melt" off without some mechanical means (scraping/picking). JHM sells a great carbon cleaning tool kit and some solvents that I would have used in lieu of blasting if I'd had to.

-Jon