What are the real differences between the S8 and the S6

A6 All/ S6 All
#21

Picking up where we left off.

http://audirevolution.net/addons/albums/images/619428370.jpg

There is a good reason why so many have seen a great big improvement going to a custom 3" exhaust for their V10 S6 or S8

The stock exhaust on the S6 and S8 are both the same size. The S8 has better bends and no crimp points, but both exhaust systems have the same small exhaust. They are not even 2.5" The 4.2 RS4 has a bigger exhaust than the 5.2 V10 S6 and S8.

The total size for the V10 exhaust is

http://audirevolution.net/addons/albums/images/852870710.jpg

Yes, that’s 2 3/8’ that’s is very small when you think about the total flow of the V10.

Still, we know the S6 and S8 exhaust are undersized but what are the other differences between the two exhaust systems?

Other than having much better smoother bends with no crimps the S8 has what looks to be an X pipe. We all have seen just how much power can be gained by placing a proper X pipe in an exhaust system.

http://audirevolution.net/addons/albums/images/140279339.jpg

The S6 has what looks to be an H pipe.

http://audirevolution.net/addons/albums/images/409900215.jpg

There are two very different parts to each exhaust. The real question is are any of these performance adding add-ons functional? Next week we will cut them open and see.

#22

That’s interesting, why would Audi not put an x in the s6 vs s8

#23

Its interesting they are both the same size. but that the S6 has all the smashed and mashed areas. Then the X Vs H section again is interesting to see. Im excited to see if any of those are functional.

I really think the only difference is starting to look like just the exhaust the air box and the gear raito.

#24

Last we left off, we were waiting to see if the OEM Audi exhaust systems on the S6 and the S8 used the X or H pipe flow technology that we see on so many performance exhaust systems.

http://audirevolution.net/addons/albums/images/579069160.jpg

First up let’s look at the S6. What are the real differences between the S6 and S8? We can see the exhaust systems are different but is it enough to make the S8 have the extra hp?

The S6 looked like it has an H pipe. We know the added power gains of adding flow technology like an X section crossover or even an H, but did the Audi S6 team use it.

http://audirevolution.net/addons/albums/images/409900215.jpg

When you look further, there is no cross over. The section is just there to support the structure. There is no H pipe.

http://audirevolution.net/addons/albums/images/291302678.jpg

So far, we have seen the S6 has a more restrictive exhaust with crimps sharper bends and now no crossover section.

Now it’s time to move on to the S8.

Here is what the possible crossover section looks like on the S8

http://audirevolution.net/addons/albums/images/140279339.jpg

With a section that looks like that and with so many welds in the area there has to be something in there.

Sure enough, there is.

http://audirevolution.net/addons/albums/images/867033232.jpg

Sure, this is way less than optimal when it comes to a well-made X section but it continues the trend, that the S8 exhaust has more of an actual performance approach to it than the S6.

The more and more I look, the more and more the S6 and the S8 are not very far apart and it seems like closing any possible gap between the S6 and S8 is as easy as an exhaust and maybe a better flowing air filter.

#25

No surprises there. How can we measure whether the s8 heat soaks less if at all :slight_smile:

Nit that important but what do prod numbers look like between the two per year?

#26

Wow that explains a lot and shows a good argument on why the S6 guys see such great results with exhaust work. Espically when they get a real exhaust with a X pipe

#27

I wonder if I can get just a real x pipe on the 8 and see if it helps it even more.

#28

Yes it does. Basically fab speed setup Google that and do something similar ish

#29

Do you still have the stock exhaust. If your close to the detroit area I would just have countvohn make you an exhaust. They made both my headers and catback.

Also the X section needs to be placed in a different location depending on your over all set up

#30

https://youtu.be/7jvvTyCZvQw
From fabspeed

#31

What a rip off. It looks like the same size as stock and its not even a true X pipe. Your spending too much money to remove the resonators. What a waste. Why would you put a part on that creates drone. the resonators are there to cut down on the one thing that nobody wants drone.

Fabspeed this is a big PASS what a joke.

#32

Yeah I was thinking the same thing. $1500 for more noise that the wife will hate and not get me what I want.

http://m.summitracing.com/parts/sum-640700
Something like this can’t be too much to get installed.

And I’m in MN so Detroit isn’t close enough that I could have something made.

#33

I didn’t say buy fab speed, but I used there principals but with 2.75 inch piping and it worked great! For about 600 :wink: btw piping on favspeed is like 2.5ish so rs still improvement over factory wth better config just jot ideal but the design is decent actually. Not as good as custom but usually isn’t

#34

That would be a good thing to just swap out the current X you have and put that right in its place

#35

I was thinking when I made the post that… I dont want VTGT to think my response was aimed at him but at the fact that fabspeed actually was charging that much money and actually selling something like that… that wasnt really better

#36

Hehe all good, I was going to buy and see if it fit my s6 but since it is s8 fitment only; after talking to my exhaust shop it was a no brainier to do custom. I sent him that we followed similar design principles with larger diameter piping and we took it further back near rear section and stock mufflers and as far fwd as we could with great x pipe location and wonderful result imo. Cannot underestimemate difference of truly well design exhaust components on these cars, it’s almost night and day when done correctly.

#37

So as we start to see actual performance results from these cars now that JHM is offereing performance parts and tunes for these cars it looks like the actual differences are

The S8 has a much better exhaust stock
The S8 has a better air box design but i dont know if that makes too big of a difference
The S8 has a better finial gear raito.

Can anyone look up the actual part numbers for the S6 and S8 camshafts… I noticed that S6 and S8 have different motor codes so there has to be something different there. I have seen that the throttle bodies are the same the intake manifold is the same the cats and the exhaust manifolds are the same.

The good news looks like you can pretty easy make a S6 as fast as an S8 with a few parts. If you put the JHM 2.75 exhaust on a S6 you have fixed the biggest performance in hibbiting part.

In theory if both cars had the same exhaust they should be able to make the same power. Unless there is something going on with the cams.

#38

So I took my own advice and looked up the part numbers for the camshafts on both the S8 and S6 turns out.

The camshaft part numbers for both the S8 and S6 are the SAME.
The S8 V10 motor code BSM camshaft numbers
The S6 V10 motor code BXA camshaft numbers are all the same both intake and exhaust

As time permits and if anyone really cares I will look at the actual cylinder head part number the valves and even the pistions. So far the gaps between the S8 and S6 motor wise dont look very big