I've been scanning the net for 4.2L mods for my 2003 A6 and don't find much. I noticed the newer 4.2L's have an extra 50 hp or so. What changed on the newer 4.2L's to give them so much more power? thx!

 

Beware of products which claim to give a 50 HP gain, but which are illegal. This is mostly a problem if you are required to have an emmisions inspection.
However, if you run VAG-COM, there are no codes and all of the emissions monitors are OK, then there may or may not be a problem, but it is less likely.
In some emmision inspections, they may look for illegal devices, if you fail.

 

Probably changed to FSI

 

They probably just changed parts of the engine around or programmed it differently. For example, there are a good amount of Audis that have used the 4.2L engine. The A6, A8, RS4 (I think), S4 (I think), and Q7 have all used the 4.2L engine with different performance results.

Its the same with the TT when it received a bump to 225Hp from 185Hp.

 

Yes, I am sure they changed things around. The S6 and the A6 use the same engine but the S6 has another 40 (not 50 as I mentioned earlier) hp. If it was a head change or cam change something like that I could understand but they must have done something more than just program it because none of the Revo or other ECU flashes get you anything near 40HP more over the basic 4.2L. I can't find a description of what changed anywhere. If anyone knows, I am all ears. thx

 

well are you talking about changes from the C5 4.2 to C6 4.2, or C5 A6 to C5 S6?

 

he said newer, so i'm assuming C5 to C6

 

but in the last post he brought up the S6, which in new models has the V10

 

I know you can get a computer upgrade to take the regular 4.2(300hp) to S6 4.2(340hp). Forget who has it, maybe neuspeed or something. Raises out-put and rev-limiter. The brand new ones are FSI, I think 350 or so hp, I know thats what it is in the touareg and Q7.

 

Sorry for confusion about C5 to C6 and all. Actually, take your pick. What's changed on the 4.2L "normally aspirated" that put out 340hp rather than the 299 hp mine has? For example, the 2003 A6 4.2L has 299HP, the 2003 S6 4.2L has 340Hp. I have not seen any ECU upgrade the claims to take the 299HP version to 340HP. For an NA motor, it does not seem feasible to extract 40HP from an ECU tweak (turbos yes, NA, no).