Winter Project: C5 RS6 upgrade

[vtraudt]

Here is my plan:
- upgraded turbos (custom RS6 based, billet compressor); high torque. Fully spooled at 3k rpm (22 psi to redline; see below).
- injectors
- downpipes
- cat back
- custom tune (maintaining N75 boost control, and will live with the stock MAP limit of 22 psi). 7200 rpm redline.
- TCU tune
- tranny valve block refresh; possibly higher line pressure solenoid

Concern:
a) should I upgrade the stock torque converter?
b) how much torque can the tranny handle?
c) added cooling capacity for trans fluid? (forgot, but assume standard Audi setup with tranny cooler incorporated into radiator).
d) Intake Air Temperature: for cosmetic reasons, FMIC may not be a good option. Stock IC are tiny. Commercially available upgraded once don't really do that much and cost a fortune. Water/meth the smarter way to go? Or can the stock IC handle 600-650 cHP?
e) I normal put upgraded motor, tranny and snub mounts in (2.7T). Similar for the RS6?

Other bottlenecks, upgrades I should consider with the engine/tranny out?

[Korben007]

What witchcraft do u think will make 22psi at redline?

[vtraudt]

For example this one (on 1.8T B6; running only 50% duty cycle on N75 at 7200 redline; PLENTY more flow. Currently at 340 cHP and N75/stock MAP limited).

http://i1273.photobucket.com/albums/y407/KraftwerkTurbo/TM5092814_zps9bdffc7b.png

15646

[10SecS4]

You can't compare a single turbo 1.8 4 cylinder to a twin turbo 4.2 V8.

Like Korben007 said, you're not going to be able to run anywhere close to 22psi to redline with RS6 turbo hot sides. You'll need larger turbochargers and even then you're going to run into space constraints, transmission limitations, etc.


For example this one (on 1.8T B6; running only 50% duty cycle on N75 at 7200 redline; PLENTY more flow. Currently at 340 cHP and N75/stock MAP limited).

http://i1273.photobucket.com/albums/y407/KraftwerkTurbo/TM5092814_zps9bdffc7b.png

15646

[lswing]

vtraudt, what's your location?, add it if you get a chance.

I think the upgraded TC's just have better seals that don't fail, otherwise very solid, unless you want to change your stall speed. Contact TozoM8 or EDGE regarding the TC. And...the TC is cheap, it's the destruction of your trans that will happen next. I've already ended the life of two, and that's with an aggressive tune. The trans can handle stock power, so plan on another $3-5k for a rebuild, might want to do it while the car is apart, or roll the dice if labor is easy/cheaper for you.

Some of us have looked into upgraded trans/oil coolers, but I think only the FMU? company made some, should help.

Upgrade the stock IC's, or at least seal up your stock ones, but no reason to not rebuild them with Apikol/others ($500-1k) for more cooling and durability, or new Wagners for $2k.

W/M is a great and cheap option and it's really helped me sustain power when outside temps are above 60F, along with tuning for a bit more power. I've gone with DevilsOwn, dual .05 nozzle sprays to each side of the y-pipe just before the intake.

At least put Hotchkis sway bars on, you'll be amazed how much they control the body roll. Add new IC piping while your at it since you're looking at going more boost. Have you looked into the hybrid turbos from Scroll with bigger impellers? Guessing you're getting the custom tune at AMD, or where? Sounds fun, cheers!

Custom headers, manual trans (handles power, allows space for larger turbos), if you really want to go big....

[vtraudt]

You can't compare a single turbo 1.8 4 cylinder to a twin turbo 4.2 V8.

Like Korben007 said, you're not going to be able to run anywhere close to 22psi to redline with RS6 turbo hot sides. You'll need larger turbochargers and even then you're going to run into space constraints, transmission limitations, etc.

Korben and 10Sec: I did not ask anything about turbos. Not sure why anyone is talking about it. Let those be my concern. As far as turbos are concerned, I know what I am doing. Believe me. And for those who do not know so much about turbos: The RS6 is a 2.1 liter, about 10% larger than a 1.8T. Specific HP is the same as the 1.8T in the Audi TT. On stock block, stock MAP, N75, we are making 680 HP on 2x4 cyl and 3.6 liter, with wastegate 50% closed (keep that in mind), turbo no even 'warmed up'. We expect that turbo to flow 800 cHP easy in twin configuration with 3 bar MAP.

So back to my RS6 specific questions, if you would.

[lswing]

I would add, have you seen the tuned KO4 fall off the charts around 4,500 rpm on Dyno graphs? Maybe it will hold longer when modified...

You're making 680hp on stock 3.6L V8, not getting that description, it takes a lot for our engine to get there.

[vtraudt]

vtraudt, what's your location?, add it if you get a chance.

I think the upgraded TC's just have better seals that don't fail, otherwise very solid, unless you want to change your stall speed. Contact TozoM8 or EDGE regarding the TC. And...the TC is cheap, it's the destruction of your trans that will happen next. I've already ended the life of two, and that's with an aggressive tune. The trans can handle stock power, so plan on another $3-5k for a rebuild, might want to do it while the car is apart, or roll the dice if labor is easy/cheaper for you.

Some of us have looked into upgraded trans/oil coolers, but I think only the FMU? company made some, should help.

Upgrade the stock IC's, or at least seal up your stock ones, but no reason to not rebuild them with Apikol/others ($500-1k) for more cooling and durability, or new Wagners for $2k.

W/M is a great and cheap option and it's really helped me sustain power when outside temps are above 60F, along with tuning for a bit more power. I've gone with DevilsOwn, dual .05 nozzle sprays to each side of the y-pipe just before the intake.

At least put Hotchkis sway bars on, you'll be amazed how much they control the body roll. Add new IC piping while your at it since you're looking at going more boost. Have you looked into the hybrid turbos from Scroll with bigger impellers? Guessing you're getting the custom tune at AMD, or where? Sounds fun, cheers!

Custom headers, manual trans (handles power, allows space for larger turbos), if you really want to go big....


Much appreciated!

Tranny: has anyone tried the higher line pressure solenoid? More pressure on the clutchpacks should result in shorter 'slip' time and higher torque holding. What ARE the weak parts in the tranny itself. Scotty (advancedautomation) also commented the TC is pretty sturdy (and he offers a beefed up one). In deed cheep enough to consider. I have been looking for stronger trannies, (for example V10 Touareg TDI, or the V12 TDI (I have German connections), but they don't bolt up.

The 01E manual tranny (I have a few of those; hopefully my Allroad will be back in business, and putting out the (stock block limited) 600 cHP I am aiming at (may need to cap lower if torque gets out of hand). But a auto to manual swap is currently not in the picture (at least for now). I recently did an auto to manual on a AR. On the 5Hp19FLA, I keep the power/torque at 400, but no long term experience yet. So tranny remains the focal point. Need to research the weak points of the internals, and see if/how they can be improved. Yanking the tranny out is no fun.

SMIC: Stock once with plastic end tanks (just an assumption, haven't even looked at them, admittedly) are obviously an issue. IMO, the fancy upgraded SMIC do not offer an acceptable cost/benefit ratio. They are still 'small', physics/size DOES matter. In addition, recently put a 'phat' (4.5 inches thick) Apikol SMIC on, and that was a HUGE disappointment. While the size increase is dramatic, the extra size does not see efficient flow for decent heat exchanger efficiency. An cheapo ebay FMIC at less than half the price had MULTIPLE better heat exchange. So its either water/meth , with 2x single nozzle plenty of distance before the TB (for max IAT effect, maybe dual setup with a pair closer to the valves for additional knock reduction; (I run 3 DevilsOwn setups, 2 of them with dual setups), or FMIC (I need to check available photos to judge how 'ugly' it would be).



Tuning is done 'in house' (we also did the current stage 1 tune; lots of 2.7T, 1.8T, 2.0T and a Cayenne), so that part is easy. Ditto TCU tune. Also have 'in network' valve body shop (with flow bench, solenoid manufacturing, testing, etc) and tranny shop. And certainly turbo manufacturing.

Headers: The 1.8T is miserably small. The 2.7T are actually flowing well. I do NOT know anything about the RS6 headers.

BTW: how are the RS6 block internals? We upgrade the rods first on 1.8T and 2.7T above a certain threshold. I was under the impression that Cosworth probably put some good stuff in there. What is the commonly accepted limit for the stock block? I am convinced the 5 valve heads are similarly efficient as on the 1.8T and 2.7T, so nothing to worry about (on those smaller engine, even at doubling the stock output is not making the heads a limitation). Using that rule of thumb, the RS6 should be good for 800 cHP at least, or?

Hotchkis: if those perform on the RS6 similarly as on my Allroad, its a no brainer. Converted my AR from steam boot to go kart (well, may not quite).

Tranny cooler: Just and idea: but if FMIC is doable (optics), there is plenty of intercooler space where the SMIC were! Splice some IC inline with stock?

Another subject I didn't bring up initially: engine cleanup. I assume I find a similar mess as of useless junk on the Cosworth 4.2 as on my other Audi: EGR/Kombivalve, PCV, EVAP, SAI. If so: any good write ups how to delete them (plumbing)? Or just do the same we do on all our engines (remove, plug up and tune out; together with rear O2).

Upgraded DV are already on (naturally, done with stage 1 tune; ditto colder copper plugs).

Ignition coils: "old style" coils and ICM? Or already newer "FSI" coils (no ICM)? If old with ICM: will rewire for newer, stronger FSI coils (very good experience with those).

MAF: should be fine for now; easy upgrade if needed, remap the tune for larger MAF housing if pegging (nice problem to have, I assume).

EGT sensor: we keep those for now. I think those are wideband (i.e. full temp range; unlike the narrow band that only trigger above threshold temp; less useful).

Does the RS6 also have the after run coolant pump? If so: reminder to put lower temp thermostat in right away.

Timing belt was recently done (right after we bought the car; just to be sure), so i don't plan to open up the heads/valve covers/etc.

[10SecS4]

You're not going to make anywhere close to 22psi to redline or 800 HP at the crank with K04s. It doesn't matter what size the compressor wheel is, you're still going to be restricted by the tiny exhaust housings.


Korben and 10Sec: I did not ask anything about turbos. Not sure why anyone is talking about it. Let those be my concern. As far as turbos are concerned, I know what I am doing. Believe me. And for those who do not know so much about turbos: The RS6 is a 2.1 liter, about 10% larger than a 1.8T. Specific HP is the same as the 1.8T in the Audi TT. On stock block, stock MAP, N75, we are making 680 HP on 2x4 cyl and 3.6 liter, with wastegate 50% closed (keep that in mind), turbo no even 'warmed up'. We expect that turbo to flow 800 cHP easy in twin configuration with 3 bar MAP.

So back to my RS6 specific questions, if you would.

[vtraudt]

I would add, have you seen the tuned KO4 fall off the charts around 4,500 rpm on Dyno graphs? Maybe it will hold longer when modified...

You're making 680hp on stock 3.6L V8, not getting that description, it takes a lot for our engine to get there.

Plain jane K04 run out of breath at 5k. They have tiny compressors. The largest in the K04 family are the TT225 and the RS6. Great standard upgrades for 1.8T and 2.7T. But not flowing much, and fairly old design (and efficiency). The billets we are using flow WAY more and at much higher efficiency.

Math: 340 HP on 4 cyl 1.8L = 680 HP on 8 cyl 3.8L. Same cyl head design, same specific HP same specific turbo flow.

Cross my finger (first brief fire up today): hope to post some logs of my current build (stock 2.7T) in next 2 weeks. Shooting for no more than 600 cHP, happy with 550 (if I need to detune to keep torque down (and stock rods alive). Since I decided to keep stock block, I opted for the smaller of our billet turbos (TM5, vs. the TM5+ that will go into the RS6 (could also put the TMM1 in, but those just seem too big for RS6 tranny and fairly low power we are planning (way under 200 HP per liter, so mild by our standards).

[lswing]

I've got upgraded VB pressure in the new trans (it will thump the gears together well, assuming max the builder wanted to put in, or could), plus an extra clutch in each clutch pack I believe, and maybe upgraded discs, and MTM TCU chip to tighten things up. Burnt up the previous one somehow, we don't know how yet, but this one has been holding up, but I haven't hammered a few hundred WOT shifts off of redline. Big problem seems to be the clutch discs that make up the clutch packs are small, like hand sized, there is a great tear down thread that's been cross-linked here from rs246.com, search for trans rebuild.

Interesting idea about moving the oil cooler to one side and trans to the other, interesting...did you pull the fog lights and open up space for air to breath on the upgraded IC's in stock spot, seems to work well. Seems like FMIC would have flow problems without any space behind it, and plenty of hot objects, while air passes right through the sides, and even more if you remove the secondary radiators, although not sure how smart that really is.

What software do you use for tuning/direct access, Bosch software for ME7? I've always wanted to know or see the platform the GUI tuning interfaces are built on, message me if you don't want to post it.

Edit; OK, so you guys have re-tooled the compressor wheel to fit in the RS6 KO4 producing a good amount more boost it sounds. Sounds like what Scroll offered me a while back, it was bigger compressor or something, and cut in our out piping to fit a larger size.

[vtraudt]

I've got upgraded VB pressure in the new trans (it will thump the gears together well, assuming max the builder wanted to put in, or could), plus an extra clutch in each clutch pack I believe, and maybe upgraded discs, and MTM TCU chip to tighten things up. Burnt up the previous one somehow, we don't know how yet, but this one has been holding up, but I haven't hammered a few hundred WOT shifts off of redline. Big problem seems to be the clutch discs that make up the clutch packs are small, like hand sized, there is a great tear down thread that's been cross-linked here from rs246.com, search for trans rebuild.

Interesting idea about moving the oil cooler to one side and trans to the other, interesting...did you pull the fog lights and open up space for air to breath on the upgraded IC's in stock spot, seems to work well. Seems like FMIC would have flow problems without any space behind it, and plenty of hot objects, while air passes right through the sides, and even more if you remove the secondary radiators, although not sure how smart that really is.

What software do you use for tuning/direct access, Bosch software for ME7? I've always wanted to know or see the platform the GUI tuning interfaces are built on, message me if you don't want to post it.

Edit; OK, so you guys have re-tooled the compressor wheel to fit in the RS6 KO4 producing a good amount more boost it sounds. Sounds like what Scroll offered me a while back, it was bigger compressor or something, and cut in our out piping to fit a larger size.

Thanks for the tranny idea with extra clutch. I will run it by our tranny experts. By the time the RS6 tranny is due for surgery, we should have first hand experience with the higher pressure solenoid.

Turbos: Haven't checked what Scroll does. But Loba (Germany) for example is using a similar concept. Nothing new. Just new manufacturing capabilities result in more efficient designs and materials. Getting 200 more peak HP out of the 4.2 (we are even pushing the stock hard in its current stage 1 trim at 540 cHP) is really not the issue at all. Check out the 1.8T and 2.7T forums. There are B5 A4 around with 700 cHP (ptzero for example drives his since years with 700 cHP (and has the dyno charts and 1/4 mile slips to proof it). And plenty of 2.7T with rods at 800 cHP.

Upgrading the TC is a check.

FMIC or water/meth needs to be decided (also need to check on 'non plastic end tank' SMIC plus water/meth). Will also consider the results from my 2.7T FMIC in the decision (I have a 4 bar MAP (UK sourced) and the corresponding mapping for the tune, so I am not limited to the stock 22 psi; see how the FMIC works).

Tranny remains biggest issue.

[vtraudt]

What software do you use for tuning/direct access, Bosch software for ME7? I've always wanted to know or see the platform the GUI tuning interfaces are built on, message me if you don't want to post it.

Yeah, the Me7 has been dissected thoroughly. And TunerPro and other GUI are available. And all of 1800 pages of the Bosch manual (in German, so at least that works for me).

But amazing that still areas pop up where 'no one has gone before'. Example: the algorithm Bosch put in to calculate the EGT for OEMs that don't want to use actual EGT sensors. Bosch provided instructions to the OEM to plug in empirical data from their actual engines at various locations, and the Bosch algorithm calculates the resulting EGT from available engine data. Instead of just 'bypassing' those values (and the corresponding 'correction' steps the program is then issuing to the ECU (from lowering desired boost to pulling timing out to throttle cut), we ended up putting EGT sensors on our modified engines and measured the temps (just like the OEM/Audi) and plugged them into the Bosch software. This way, we can maintain the built in original 'safeties'. Ditto the hassle and limitation of controlling higher boost with N75 (most, if not all tuners just switch to MBC or EBC). But that again would take one of original 'safeties' out. Since our cars all are daily drivers, we have put a high emphasis on fail safes, etc. Running out of meth? No problemo; "we have an app for that". Automatically. I have plans to use the 'Funk' switch as a "wife/valet/kid" mode (10 psi boost).

[Avus-RS6]

You're not going to make anywhere close to 22psi to redline or 800 HP at the crank with K04s. It doesn't matter what size the compressor wheel is, you're still going to be restricted by the tiny exhaust housings.


I agree and can personally vouch that they will not hold 20+to redline even with my larger billet internals. I think they taper to 14-15 after 6000rpm. You might be able to get a couple more psi by opening up the intake and install a freer flowing exhaust but I very much doubt any more than that.

[Other_Erik]

Sounds like a very interesting project to say the least!

Isn't there an Aussie on here who just picked up a #REKT RS6 down under to driveline swap into his AR Ute? IIRC he's looking to do a ~700HP build.

There's been a couple of builds over the years on here (yes, I just registered last year but have been trolling looking for good/cheap/reliable info), and so far I don't think anyone's gone beyond 670-680cHP, at least not that they've posted up here.

Agreed with others, no way to get 22psi on K04's, stock internals or not, without replumbing everything, and if you're going to do that, might as well go for relocated (where is the other question). A good solid number to shoot for would be 17-18psi at 5500rpm, and who cares if it tapers to 16psi at 6k? May actually be better for the TC/Trans to have less torque at shift speed.

General consensus is SAI is just this side of useless (basically just there to help emissions on cold startup), and there are certainly more things that _can_ be removed / tuned out - only question is what info are you willing to cut out from feeding your smart tune... are you willing to sacrifice the niceties of the stock gauge cluster for something like an in-dash display with realtime data monitored thru multiple replacement sensors? paraphrasing you here - there's an app for that. If you're looking to roll your own tune and do all of this modwerk yourself, EGR/Evap/PCV should be simple enough...

Head flow should be alright with maybe a light polish, but are the lifters/retainers up to the job? Do you need to look into more serious gasketry? How confident are you in the cam seals and plugs? Are you going to be pushing the oil pressure past what the existing seals are capable of? Exactly how far off of perfect harmonic balance are you comfortable with the crankshaft being (or are you going to yank that and get it blueprinted and balanced?)

Funk switch - haha, wife/kid/valet mode is "the key stays in my pocket" - There's already an embedded valet mode in the ECU that limits max speed, rpm, and throttle percentage, just have to have the nifty plastic key to utilize it.

RS246 has a great rebuild thread on the transmission - some guy spent 2 months accumulating various parts to more or less replace every clutch disc, seal, etc... and thankfully documented almost every step.

Haven't done a big build on anything since helping a coworker and his father put together a Roadrunner that crossed the quarter in just under 9 seconds, there are a TON of little gotchas even with a project as simple as that one... We ended up replacing every bit of rubber tubing under the hood with aeroquip and related bits - stuff built for light duty aircraft is usually much higher quality (and price of course), built to withstand greater fluctuations in temperatures and pressures, to tighter tolerances, etc...

One last thing to remember with this ambitious type of project - if you grenade it, you _can_ replace it. There've been a handful of long blocks on ebay and the like in the $4-10k range depending mileage, or you can go all out and get a direct MFR crate from Cosworth for the low, low price of ~$45,000 (plus freight). Given the funding you're likely to drop on this, I'd take the route that a couple folks here have done and pick up a second (and/or third, fourth...) RS6, full rolling replacement - whether from auction block, salvage yard, or just outright sale, you can have any part you might want to tinker with at your fingertips any time you please.

I guess a big question here is - what are you really trying to do?
Are you just looking for big HP numbers from an RS6? (remove engine/trans, replace with blown BBC, call it a day) Or do you want high-hp out of the Cosworth? I'm sure for the money you're dropping, they'd be happy to help you re-engineer it to Rally spec (760hp 660tq IIRC)
Do you have a specific goal? 1/4mi time? Trap speed? Slalom speed (hahahaha in a 4400lb grocery getter)? The more you're willing to share about your aspirations, the better the advice we can deliver here.

Wow, I'm just a wall of text, most of it questions. Most of my questions are rhetorical just to maybe get you thinking along the right lines of how to go about this. Sub'ing this thread to see OP's updates!

O_E

[vtraudt]

I agree and can personally vouch that they will not hold 20+to redline even with my larger billet internals. I think they taper to 14-15 after 6000rpm. You might be able to get a couple more psi by opening up the intake and install a freer flowing exhaust but I very much doubt any more than that.

Yes, the K04 can't flow enough to do more than 16 psi at high rpm. Check the compressor map, and you clearly see why.

[lswing]

Yes, the K04 can't flow enough to do more than 16 psi at high rpm. Check the compressor map, and you clearly see why.

OK, so are you going with a bigger housing then? Impression was you were just putting a better designed billet compressor into stock housing. Just whatcha doing to this turbo? Thanks for the tuning info, been wanting to know the open source for these.

[vtraudt]

Sounds like a very interesting project to say the least!

O_E

Thanks OE. This is by (my means) not a big project at all. Just some tuning and mods. Big project to me is auto/manu swap, building block, building head, etc.
But with the limitations (tranny mainly), at this point we will be contempt with the very limited project scope and performance goal.

I suspect the main reason for not seeing more high power RS6 projects is in deed the issue of finding a suitable drive train. I am sure the block is strong, and could be further fortified if needed. No other reason comes to mind, considering that the good old Audi inline 5 is known to make 800 HP, 2.7T 600+, 1.8T 500; we have 3.5 V6 Nissan 300Z dynoed at 600 whp (real Mustang dyno, no 'what HP number do you want us to show you today' inertia dynos), another 300Z on 3.0 liter Supra 2JZ at 720 whp, and so on.

Heads and valvetrain is plenty good. With our high torque turbo (very early spool up, unlike big Garrett, T3/T4, Tial, etc. that don't spool before 4.5k), we don't need to extend the power band into the 8k range to provide a sufficiently wide USEABLE power band. We stick with 7.2k as we do with all our Audis.

More on the tranny:
- higher line pressure: appears he increased spring pressure in the VB
- more clutch discs: likely clutch spacers machined down to make room for additional disc in, increase holding power
- upgraded clutch packs (stronger, better material)
- open: high pressure main solenoid in VB?

TC: install upgraded one for strength and durability (not holding power; stock not the limit)

TCU: tune

Motor, transmission, snub mounts: Stern Street density

Rear diff stabilizer: Maybe

Additional tranny cooling capacity: Maybe; needs more research

Intercooler: open, TBD: upgraded SMIC (at least metal tanks), FMIC, water/meth

Performance: open: water/meth for IAT and knock (with failsafe setup)

Coils: need to find out how good stock coils are, what generation. ICM?

Hotchkis: on the list; need to check what suspension/swaybars, etc. are installed from previous owner

Cat back: ditto

Downpipe: 3", cat delete

Injectors: 550cc or 750cc Bosch EV14 plus pigtails wired

Turbo: KraftwerkTurbo billet TM5+ for RS6, custom wastegate actuator (stock on RS6 are terribly weak, poor control at higher pressure)

Tune: custom tune Kraftwerk Turbo, N75 control, stock MAP (22 psi limit)

After-run coolant pump: install lower temp thermostat

Engine cleanup: Delete SAI, EGR/Kombi, Evap, Rear O2/Cat, etc. and tune out

Expected: 650 cHP, may take desired boost down to limit torque (torque, not HP kills rods, trannies, TC, drivesshafts, etc).

[Avus-RS6]

Sounds like a nice build, thanks for posting. I think you should get close to your power goals if not attain them.

There will be some big power RS6's coming out of WA state very soon, 700-800awhp range. The problem is the engine has to be dropped for just about everything, and it takes two large, expensive turbos to make big power on these cars, and when I say big power, I mean double the stock rating. Not only that, but all the fab work required for headers, downpipes, fuel system, and a new intake as our tiny airbox is restrictive above chipped power. There's not tons of room to stuff those big turbos, and not really worth while until you do a manual swap, yet another large expense. You can get a couple hundred extra ponies and a few hundred extra ft lbs with RS6-K04 based turbos, but to notch it up from there requires much much more time and money. This is why we haven't seen much of this, it's one of the least cost effective Audis to make really big power with. It does start with 450 from the factory, which isn't too shabby, and they put together a tight package that is time and $ to mod. 11 years later, we're finally seeing these cars get pushed as there's a nice handful of manual cars to play with now.

[ben916]

Sounds like a nice build, thanks for posting. I think you should get close to your power goals if not attain them.

There will be some big power RS6's coming out of WA state very soon, 700-800awhp range. The problem is the engine has to be dropped for just about everything, and it takes two large, expensive turbos to make big power on these cars, and when I say big power, I mean double the stock rating. Not only that, but all the fab work required for headers, downpipes, fuel system, and a new intake as our tiny airbox is restrictive above chipped power. There's not tons of room to stuff those big turbos, and not really worth while until you do a manual swap, yet another large expense. You can get a couple hundred extra ponies and a few hundred extra ft lbs with RS6-K04 based turbos, but to notch it up from there requires much much more time and money. This is why we haven't seen much of this, it's one of the least cost effective Audis to make really big power with. It does start with 450 from the factory, which isn't too shabby, and they put together a tight package that is time and $ to mod. 11 years later, we're finally seeing these cars get pushed as there's a nice handful of manual cars to play with now.

Off Topic:
Care to share the location of this big power build??? whom???

[lswing]

Off Topic:
Care to share the location of this big power build??? whom???

Guessing AMD....here's a pic of one of our blocks that's been upgraded, along with custome headers and bigger turbos, going into a A4 stripped frame I think. Just from some Facebook posts, was hearing numbers like 800 cHP I think...race car! 15649 Thread jack complete!

[ben916]

Guessing AMD....here's a pic of one of our blocks that's been upgraded, along with custome headers and bigger turbos, going into a A4 stripped frame I think. Just from some Facebook posts, was hearing numbers like 800 cHP I think...race car! 15649 Thread jack complete!

Lovely time to dyno the motor!
Anyone got 100 miles of sensors and a couple of MAFs and O2 sensors, and cam tensioners and and and and..................

I would LOVE to see someone get bigger snails on 4.2 lump in the C5 RS6 (not the Gumpert)

[Korben007]

The reason it's so hard to get over 600 chp is because of the plumbing. The headers are just to small!

[Turbowned]

I'd like to think that by the time I pay off this car I'll be in a position to build it up for big numbers... but then it becomes a matter of "do I spend a ton of money on an old car or do I just buy a better car for the same amount I would've spent?"

At least that's what I'm running into with the BRZ; I could've bought myself a nice gently used E92 M3 or 997 Carrera S for the money I've spent on this foolish Subaru :doh:

[DHall1]

Who needs a firewall.

Hell just strap a seat on that bad boy and take er for a ride


Guessing AMD....here's a pic of one of our blocks that's been upgraded, along with custome headers and bigger turbos, going into a A4 stripped frame I think. Just from some Facebook posts, was hearing numbers like 800 cHP I think...race car! 15649 Thread jack complete!

[DHall1]

Primary reason my mod list stays in check. I dont ever go insane on builds just to say my car ran this or that or put down a dyno.

I just build to tweek a few driving specs and make my boring commute spicy.


I'd like to think that by the time I pay off this car I'll be in a position to build it up for big numbers... but then it becomes a matter of "do I spend a ton of money on an old car or do I just buy a better car for the same amount I would've spent?"

At least that's what I'm running into with the BRZ; I could've bought myself a nice gently used E92 M3 or 997 Carrera S for the money I've spent on this foolish Subaru :doh:

[Bigglezworth]

Yet another post about someone getting ready to labotamize the 4.2 and inject more money than makes sense to many trying to extract more power out a 2 ton tank. Sorry to the OP, but this post isn't the first time we've seen these 'desires' and it won't be the last. Best of success with whatever you end up doing. No matter what you choose you will find your wallet significantly lighter, and be eating up other weaker links in the chain as a result. Why wouldn't you want to put all this time and money in to a car that can benefit better from your labour of love?

[vtraudt]

RS6 (according to post) have fairly weak wastegate actuators.
Add to it the expected high back pressure, and controlling boost at high rpm might become an issue (wastegate getting pushed open).
I have not found suitable upgrade actuators. Is the only solution to fabricate custom ones (10 or 12psi or 1 bar)? Any suggestions?

[Korben007]

I boost about 11 psi on wastegate pressure with k03 waste gates

[lswing]

I boost about 11 psi on wastegate pressure with k03 waste gates

That is 11psi wastegate pressure compared to ~6psi stock wastegate pressure just to confirm. What are your actual/specified boost numbers?

Any chance you've got a dyno readout to see how the boost holds compared to stock wastegates? Stock wastegate seems to allow boost to hold strong at 15-20 psi (depending on tune settings) until 4,500 RPM's, which is typical.

[vtraudt]

That is 11psi wastegate pressure compared to ~6psi stock wastegate pressure just to confirm. What are your actual/specified boost numbers?

Any chance you've got a dyno readout to see how the boost holds compared to stock wastegates? Stock wastegate seems to allow boost to hold strong at 15-20 psi (depending on tune settings) until 4,500 RPM's, which is typical.

Did the K03 actuators bolt up (both sides) to the RS6 turbos?
K03 from 1.8T longitudinal (for example AEB, AMB, or similar)? I thought the RS6 geometry is 'special' and no other (donor) actuators fit.

[lswing]

For reference, 80 degree day, approximately 15-17psi tuned (depending on conditions), stock wastegates (I think, it's possible the guy at Scroll turned the arm once to stiffen it up, forget). The taper of boost around 4,500 rpm seems very common from the charts I've seen for most every tuned RS6. To hold boost to redline, or close, would be sweet.

http://audirssix.com/images/RS6_dyno2.jpg?lbisphpreq=1

[vtraudt]

Looks typical. Need to dig out the stage 1 (stock everything) log.
And yes, want to sustain slightly higher boost to redline with the turbos we built. But clearly, at high flow (and corresponding higher exhaust flow and backpressure (have downpipes though), we expect much higher backpressure. And with the weak RS6 stock wastegate springs, expect the wastegate getting pushed open (backpressure) at high boost, high rpm. Hence: would like to see 12 psi or so crack pressure actuators, but can't find or can't figure out if some 'take offs' (other models) can be used.

[vtraudt]

Found the mild stg1 log (3rd gear): 16104

[lswing]

Yep, 3rd gear also, closest 1:1 ratio. Looks like boost tapers just where torque typically does. You could always call Scroll. I hadn't looked into it much at the time, and was in a hurry or might have increased the wg pressure.