C5 S6 V8 power build

A6 All/ S6 All
#1

Hi everybody, I’m Boatmobile. I’ve heard great things about this forum. AudiRevolution’s v8a6 suggested that I join the revolution.

I’ve owned a chipped B6 A4 Avant 1.8T for a few years. It came with some mods, and since I’ve owned it, I’ve removed some aftermarket stuff, and I’ve added some things as well. I originally wanted to put a big turbo in it, but it’s just a four cylinder, so I’ve decided I’d rather make a project out of a C5 S6 Avant V8, which I plan to buy this month.

The legendary RS6 Avant is still unavailable in North America, so I’m here hoping to learn more about what’s involved in getting progressively more and more power out of the already mighty C5 S6 V8, and, see what I can contribute to this community along the way, from my own amateur adventures of modding and un-modding my B6 A4.

#2

Welcome to the forum, you came to the right place especially since you will be driving a V8. You’ll find that there is boatloads of information on this site. Are you keeping the A4 or selling? What options do you plan to go for with the S6? Also, pictures would be awesome.

#3

On a side note, as a preface to feedback, the C5 S6 4.2L V8 engine is a timing belt driven engine, not to be confused with the B6 S4 4.2L V8 engine which is a timing chain driven engine. Same era, different engine. So the S4 parts/etc are not necessarily compatible with the S6.

In about two weeks, once I have the S6 Avant, I will post a list of existing mods on the car, and from there I hope to juggle ideas regarding what you guys think would be my next/best move. In the meantime, I’d value any and all feedback on starting point(s) for a build that I hope will involve a supercharged rebuilt engine.

#4

Welcome Boat!

Hold on a second… are you sure you aren’t a BOT ???
LOL

Glad you finally made it through the tight screening process here.

For those who don’t know, Boatmobile is planning to purchase my C5 S6 Avant, and take it to the next level. The car is getting a few final upgrades under my care before it is passed on to Boat. This weekend it will get a Magnaflow catback, an H&R rear sway, and some other odds and ends.

http://ep1.pinkbike.org/p4pb11080549/p4pb11080549.jpg

The car is one of 83 C5 S6s that was sold in Canada, and the pearl white making it even more rare.

There is a lot I love about the car, but my favorite part has to be the interior with the Alcantara lined sport seats. They are super rare, have an amazing feel and they grip your ass so you don’t slide around as much as you do on the all leather ones

http://ep1.pinkbike.org/p4pb9210332/p4pb9210332.jpg

Current mods

H&R coilovers
Brembo 18z with JHM 350mm lightweight rotors
Magnaflow high flow cats
Gruvenparts billet intake actuator arms
Magnaflow catback and H&R rear sway to be added this weekend

So, while Ill be sad to see it go, I know that Boat has his own plans for the car that will definitely take it to the next level and beyond.

It would be nice to hear a bit more about your current Avant. It is also a very cool car.

#5

One of the great things about AudiRevolution is that if you dont already know all the differences between the belt driven 4.2 engines and the chain driven ones, then you are immediately voted off the forum.

It is pretty much a prerequiste around here to know almost everything about the v8 Audis :slight_smile:

The core of the forum was built around them.

#6

Thanks MDUBZ. Haha and thanks v8a6. I’m not a robot and I’ve never been in Area 51. But yeah I’ll be holding onto the A4 Avant for at least another year or two, until the S6 has had all the work done on it that I would like to get done. I plan to post 360 degree view pictures of my current Avant in the B6 A4 section within the next week. It has three colors, and it gets compliments from strangers, so I like to think it’s not a circus of nonsense lines and colors. I call it the “4x4 boat”, and I’ve never posted pictures of it anywhere with all three colors, but AudiRevolution can have them to share with the world. I’ll add some info about my A4 when I put up the pictures.

#7

Welcome the S6 4.2 is awesome because it looks like a b6 S4 but still has the A6 4.2 belt motor. If you know the right people there is a lot of great parts for the older A6 and S6 cars.

#8

Headers really woke my A6 up

#9

I think you must have been one of the first guys to do the JHM headers on the A6 4.2. I heard they added a TON of torque.

Do you happen to still have any pics?

#10

Just found a pic of your old JHM headers Bee…

http://img693.imageshack.us/img693/4283/bothwithjig.jpg

So sweet :slight_smile:

#11

And a clip of you running your old car down the highway.

https://www.youtube.com/watch?feature=player_embedded&v=OlPXTAgOAWA

I love how the headers make the car sound so refined, yet raw at the same time.

#12

FTFY

Got to help the install…although I mostly just gassed these guys to near death.

#13

Gas station taquitos lol

#14

Yeah I do have a ton of pictures. My internet is down at the moment, but once its back I’ll post the up.

I can’t quantify the torque gains, but the car felt like it pulled as hard at 2k rpm with headers as it had at 3k without, ie the torque curve was translate 1k rpm earlier.

#15

Hahaha. I’m not the most useful in the shop either, but I try :slight_smile: I’m good at taking orders

#16

Nice! I have never had the opportunity to drive a car with tuned headers, so I am definitely looking forward to the chance to drive one.

#17

Hey guys thanks for gettin in on this thread. I actually read about a header install that at least a couple of you guys had commented on over on 'zine. I’m hoping to get some legit JHM headers bolted onto v8a6’s Avant soon after I get it. Giddy up!!

#18

Hi Beemercer, did you do any other power building on your A6 besides the headers?

I’d also welcome any power building ideas/upgrades/mods regarding this platform from anybody here on AR. I’m really interested to hear about any upgrades that have been done, or that could be possible, so that I can learn more about them. Even custom parts too.

#19

Check the video of Beemercers car that was posted above. His mods are are listed right at the beginning.

For the 4.2 S6/S8 or the 4.2 S4, the formula for naturally aspirated power has been pretty well defined by JHM and guys like Beemercer.

  • Piggie pipes (good) OR catless downpipes (a bit better) OR JHM headers (the best)
  • 2.5 inch x-pipe catback
  • Downstream High flow cats or straight pipe exhaust
  • JHM tune

Other items that will make your car quicker, but not specific to the 4.2 are

  • Lightweight Rotors
  • LW wheels
  • LW crank pully
  • LW flywheel

There is also the JHM NOS kit that is available for the 4.2 S4/S6/S8

https://jhmotorsports.com/shop/catalog/jhm-nitrous-system-for-b6b7-s4-42l-40v-p-647.html

CountVohn has done some custom superchargers for a few 4.2 A6/A8s. I believe his kits used a Kenne Bell supercharger. And for the S4 there is the JHM Vortech kit.

https://jhmotorsports.com/shop/catalog/jhm-supercharger-kit-for-b6-b7-s4-stage-p-819.html

#20

Ok cool, thanks v8a6. So just to make sure I get it, as I understand, the headers replace the exhaust manifold, and then the cat back gets it the rest of the way to the tail pipe. Two and a half inches all the way. So that’s basically best case scenario for exhaust flow, right? Of course without deleting cats or cutting off mufflers. I bet if you didn’t have mufflers then it would be louder than a helicopter. Anyone on here experienced that? Haha