let me clear up the confusion on the unitronic tune. I am a unitronic dealer (swiderski motorcar in buffalo NY) I followed their instruction to pull the file and send it out to them. They modify the file and send it back. I write the new tune to the car and I get billed for the tune. The issue I ran across was I did not receive the new file back because I requested extensive modification to their advertised file that makes things extra complicated. I am sure I would have received the file back if I had more time to wait but after a few weeks I canceled the request.

The only W12 file they have on hand ready to flash today is for the phaeton W12 ECU ID 07C906018C. You can recover the ECU ID from vagcom to see if this is the computer code you have. All that means is you would not have the tune back the same day. It means that what ever dealer you go to for a unitronic tune will have to copy the file from your computer and send it off to their head quarters so they can work their wizardry on it and send it back.

I do have a before dyno and I may take another crack at this in a little while to see how much power can be gained.

 

stage 1 is usually a pretty Conservative tune,
stage 1+ is generally a 93oct tune that is about aggressive as you can get without any hardware changes (stock exhaust, turbo intercoolers, ect)
stage 2 usually requires some hardware changes such as downpipe or full exhaust.

In my example I essentially requested a stage 2 file to be used with a full cat delete and so emissions remapping as well as removing the massive delay when applying and removing throttle inputs. It is not a easy modification when working with this car. I am sure they could do it if I gave them some more time to handle it.

 

If you are writing to the ECU from a laptop or similar computer, you will seemingly have to write to each of the two ECU's serially. That's the typical "problem" apparently since one ECU looks to the other for symmetry. If the first has been written but not the second, I think it may throw a fault code which then can get in the way of updating. Not sure if it means pulling the ECU's to do it off the wiring harness or if it requires special equipment that writes them in parallel or what.

MTM had a W12 program so presumably they had it sorted, and the dealers must too, more so for the higher volume similar twinned V10 in the D3 S8 and C6 S6 if I remember right.

If all they have is a Phaeton W12 program, I would definitely run that down more for the underlying specs and applicability. IIRC, U.S. W12 Phaeton was 420HP/408 ft lbs. (A8 = 450/428) and I thought it had the older 5 speed tranny. Thus detuned off the Audi w/ the same 6.0L displacement, plus heavier to boot. Not sure where they went with the specs in Europe after they pulled the plug on it in the U.S.

 

The ECU's are written via the OBD port. It takes considerably longer on cars that use 2 ecu's. I experienced this both when I pulled the file on my W12 and when I pulled the file on my V10 TDI touareg. Writing the files goes much quicker that pulling the file for whatever reason, but when I flashed my V10 TDI everything went without a hitch.

I can't speak on power gains or anything about the tunes on the W12. I just looked up to see what files they had available for me to write and the W12 phaeton is there on hand. I do know that I want more power and I want to hear a exhaust note, and at some point I will pursue this further to get a tune. If that means taking the car in person to their HQ for dyno time then that is what it is.

 

That really must be some wizardry to improve results of thousands of hours by engineers who know this engines inside out and have them on dynamometers years before they go into production. And all that online without ever seeing the engine. I am a bit skeptical.

 

No or manufacturer ever tunes their cars to the bleeding edge. There is always something left on the table. How much is there I don't know. Engines are not rocket science. Use good fuel and eggressive timing curves and you make power

 

First, it's an NA engine, not force fed. The easy chipping stuff just isn't going to be there as with turbo'ed or blown motors.

Second, look at what Audi itself did on the D4 to up the power on the W12, still within NA confines. It did not just massage the existing set up with a re tune, hotter cams, bigger air boxes, a bit higher compression or more exhaust. It had to go into the engine itself and both increase the displacement and rework the heads to accept FSI; with the FSI it could then bump the compression yet further.

Third, there is no known higher HP version of this motor in NA form (put aside turbo'ed Bentleys), and other respected tuners like MTM don't make HP claims for their (limiter removing) chip http://www.mtm-online.de/en/Audi/A8-...T=mw12450450qx, or for their exhaust for that matter.

Finally, I tried to say this gently on the prior post, but I think indirectly you may have touched on where your point is true, but then reveals on the A8 why you may not find anything: on "lesser" models or ones further down the price curve, Audi/VW may indeed detune it to keep prestige differentiation to the more expensive model. Thus the 4.2 from the A6 to the A8 as an example where there are known different states of manufacturer tune. Owning an A6 4.2, I can see how the air box is restrictive (and was opened up some on the S6, the S8 and the D3 gen of A8's. I can also see the throttle body is clearly sized down relative to the manifold machining, and I can guess the A8 one isn't. Other times they will do it in the exhaust a bit too. Moving to the D3 A8 W12, I mentioned the Phaeton down tuning on what is still a 6.0 motor and almost certainly the same heads, pistons, and manifolds. But, a quick tweak to the ECU's or maybe some smaller throttle bodies or MAF tubes and presto, down 30HP. If you look at the specs you had for the chip and apply it to the VW Phaeton W12 specs, it's just getting back to around the Audi W12. Thus, you can get back from the Phaeton to the D3 if you know where the tweaks were, but not really from the max state of (legal/emissions) tune where Audi seems to have left the D3.

If you solve it and can get the dyno's for it great. But since it's NA with generous manifolding on both ends, seems unlikely.

 

Not agreed. Engines are more and more rocket science. Fuel mapping especially. Aggressive timing means nothing when ECU has to retard it in order to suppress detonations. You are right about fuel, but are you willing to pay for a racing fuel? Bleeding edge wise, manufacturers are tuning their engines to the best compromise of power and consumption. You can get SOME more power by enriching mixture. What it means for a 12 cylinder gas guzzler consumption and environment is pretty clear. Though it seams you don't care much about environment loosing catalytic converters.

 

I think without removing emissions equipment getting a gain worth while would be tough because the intake manifold does not look to have much room for improvement. I disagree on the exhaust side. I feel that a proper set of headers would have substantial gains IF (and that is a big IF) they could be made to fit in there. I can say for sure that I would not be the one footing the bill to find out the answer to that one. Cat removal I would have no problem with however.

You are correct. manufactures do tune for the best compromise of power and consumption. I am more interested in increasing power that improving economy. Both would be a result of removing cats though.

 

First look at your own dyno curves. The HP is rising right up to the cut off. It's not a car that is looking choked, on either end, to me. By contrast, I can look at something like my Mini Prince turbo (R56) and see on the stock dyno curves it's being choked all day long above about 5K RPM.

Second, be sure you understand the internals of the W12. The con rods are siamesed on the crankshaft journals in pairs of two cylinders. BUT, those journals are actually offset one to the other, and there is no main bearing or cap in between. They have to do that because of the nature of the W heads and diagonal staggering of the bores on each side. That means there is a stress point on the crank at each of those offset journal areas. And in turn, that is specifically why a W12 can't and shouldn't be tuned for higher RPMs than its fairly leisurely redline. Yeah, it's forged and has really robust bearing girdles/lower crankcase assembly and all that, but that split point can't change in a W12 set up. Audi documents that in the W12 SSP if you want to read further. Meanwhile, if I were opening up a motor to make it breath better, I would likely be pushing the revs too, but that just doesn't work here.

Third, think about the S8. It's 5.2L instead of 6.0, but it likely breathes better on the intake side anyway without the compromise of the fairly byzantine gas flows of the W12 heads generally. That is a much higher rev motor than the W12, but I'm not aware they bumped the exhaust there either.

Finally, not a fan of desmogging--plus CA has checks every 2 years anyway--and the forward pre-cats are there (a lot of them) to meet smog regs since circa 2004; actually why the old C5 RS6 was a 2003 MY only.