for sure aluminum block & upgraded intake manifold then obviously tuning... possibly cams as well
(in regards to C5 A6 4.2 Vs. C5 S6)

 

Sorry didnt mean to post and disappear, thanks for covering me 2001a6, absolutely correct, FSI not to mention that the allroad 4.2 is slightly different for the A6 which is different form the S4 which is very different for the RS4

 

no prob.

 

The S6 motor has a different intake runner system, Cams, but the bottom end/compression is the same. That is if I remember correctly.

The B6S4 and allroad were the first to get the chain driven 4.2. Which is much different than the belt driven one. You can chip an allroad 4.2 to get 350chp, but thats cause its a detuned motor. The regular C5 really has no potential. GIAC will get you 12hp. Exhaust, maybe another 15. You are better off making sure the arms on your intake runners are not cracked and seized. Those things breaking alone can cost you 20+hp.

 

I'm no newbie to motors but I am to Audi's. Not familiar with these "arms" on the intake runner. How may I locate these? Thanks

 

V-tec yo!....JK'ing like someone suggested prolly the FSI or its just tuned/geared differently

 

Not sure if the touareg v8 is the same as the c5, or if its chain driven but he is referring to the 3 stage intake manifold, different lengths of runners and the arms are the things that are opening/closing the different lengths. My 2.8 has 2 runner lengths, not sure bout the c5s 4.2 but its the same concept. They are inside the manifold so you cant really "locate" them, but you can see the actuators on the front of the manifold. not sure how you would trouble shoot to see if they are functional. If they were broken, I would think it would trigger a cel.

 

They connect the valves to the selenoid. They are visible on the front of the motor just if you remove the covers. The arms tend to break, and the runners get seized in either the long of short position. It's actually very common and it happens all the time. I fixed mine and noticed an immediate difference. The car pulls much better now since it was stuck in the long runner position.

This is what the new arms I put in look like.



You guys should search it up on AW. Much info over there.

 

Yes, I get the concept. To access these arms, I have to pull the intake manifold?
Also, does a code pop up if these arms break? thx all.

 

no the arms are on the front of the motor. If you pull the big *** cover that says 4.2 on it, you will see them and the valves they control. It WILL NOT through a code. Most people don't even know these are broken.