Assume that the RS6 twin turbo 4.2 is not just a regular 4.2 with turbo's added to it (rather: internals are strengthened to handle even more power), upgrading the turbo (see 1.8T, 2.7TT, etc) would be an attractive option.

I have my eyes on a 2003 RS6. With upgraded turbo's (what are the stock turbos, what upgrades are feasable), injectors, downpipe, clean exhaust, intercooler upgrade, and others as needed (TB, intake, etc?), and the corresponding tune/file/chip (what's out there?) what performance is achievable (daily driver, no drag queen, street racer)?

 

the biturbo RS6 is an absolute animal. Get a chip and an exhaust and enjoy.

 

Do you know what the stock turbos are?

 

its a version of a k04 but with an even bigger exhaust wheel. I know I've found them before somewhere on the internet, but they are a unique size. thats why they call them RS6 turbos but they are actually a part of the k04 family.

 

I found it: they are K24. Very reliable (much better than K03, similar to K04).
Boost is very low at 0.8 bar = 11.5 psi, resulting in the torque peak coming already at 1950 rpm (like all Audis of that generation of turbo motors) and stays there until 5500 (or so) RPM when it drops off (running out of breath).

If factory is 11.5 psi, I am sure 16 psi should be possible, clean exhaust, good flowing intake and efficient/larger intercoolers added and matching injectors or fuel pressure. What size injectors are stock on the RS6? What is the fuel pressure set at?

Compression is high for a turbo'd engine at 9.8:1.

I have not found detailed information what turbos are used to upgrade, or what the offered mid 500 HP chips increase the boost to.

One power/torque limit certainly will be the transmission (5HP24A vs. te 5HP24 NON AWD). I was told that the RS6 trans uses a larger diameter torque converter vs. the S6. I don't know yet what limits the trans can handle. Anyone?

 

If you want to go RS6 you'll probably want to also go manual tranny. A good tune on RS6 turbos will put in in the 25+ PSI range. I don't know about the fuel system, but I know it can be figured out. Compression is high because they are relying on the motor for most of the power, not the turbos. The thing about high compression is that it can make the same amount of power at lower boost level, you just run a greater risk of knocking.

Are you planning on running the RS6 snail on your 1.8T?

 

What manual tranny (donor car) would fit? From a detailed project/post on forum (auto to manu swap), I have the clear notion that it is a nightmare, and therefore something I rather NOT do.

I like the RS6 as the basis since I actually DO like an automatic (convenience, daily driver), chassis (fenders, suspension), engine (if factory boost is 0.8 bar (11.5 psi) it can be assumed that 16 psi should not be an issue for stock internals). The engine is basically a well designed naturally aspirated (9.8:1 compression), good flowing engine with a bit of turbo help for the low/mid range (max. torque from 1950 to 5000 rpm). Squeezing a bit more air into the engine (16-20 psi) will further help the mid range (I don't think it is realistic to expect a turbo to spool up to higher boost already at 1950, but would like the 2500-5500 torque/boost to get raised, and maybe keep torque/boost up a bit longer).

Basically, similar curves as the once below, but extending the torque to the right by 1500 rpm.

Some consider the torque limit (durability in mind) for the 5HP24A trans at 800 Nm (600 lbft), so lets stick with that. That puts the theoretical peak HP at 7000 rpm at 800 whp (with 15% loss a chp of 920 hp). Backing off and using 600 lbft at 5500 rpm (realistic goal? Maybe, if allowing the turbo to reach peak boost for the torque at a higher - say 3000 rpm vs. 1950) will equate to 620 whp and 720 chp). THAT would then be the 'right' RS6 setup for my taste.

 

If RS6 basis proofs to be to costly (prices from 20-30k), the alternative for me would be the 2.7T basis.

I have seen nice conversions using Allroad as a basis (need to find out how the fenders are modified to not show 'seams'), lowered, widened. Trans is also the 5HP24A, but was told that the RS6 trans is using larger torque converter and may have different bell housing size, so adapter again may be needed).
I have not seen info on the torque limit of the A6/S6 auto tranny used with the 2.7T.

Engine wise: simple upgrade to RS4 level (450hp) with K03 to K04 swap is a no brainer.

I have yet to find dyno charts (ideally with boost graph overlay), but there is plenty of turbo options to get to the torque limit of the tranny (TBD!!!).

Please chime in regarding the toque limit of the auto in the 2.7T.

Or bite the bullet, and find 2.7T base with manual 6 speed tranny, lowered, wider, fenders, then either T3T4 or 2871R hybrid (should be plenty if not too much, considering the power those make on the 1.8T, and we are only dealing with a 2x 1.35T here each to make 250 whp for a total of 500 whp or 600 chp).

 

Other than the info on the torque converter which I don't have, I don't really see what you are trying to say. Are you trying to put a 2.7t into an a4? Are you planning an RS6 build on an allroad if the a4 doesn't work?

There is a guy at audiworld.com (the forums) called redneck trucker. He has all the info on auto to manual swaps. He just recently did one on a 4.2 a6, giving it the mt6 in the 2.7 a6. He did a write up about it, I don't recall it really having any specifics on the procedure though. He just kind of did it.

 

I am trying to determine what A6 base to use for my project (say: 600 lbft torque for RS6 auto trans, not sure for 2.7T auto trans but certainly >RS4 (450 chp), not sure about limits of 6 spd manu, but 500 awhp with right clutch should be no issue).

Can be done starting with:
A6 2.7T manual (turbo upgrade, lower, wider (fedder), wheels. K04 to RS4 level as easy/inexpansive upgrade.

A6 Allroad (2.7T) turbo upgrade to torque limit of transmission, lower, fender optics, wheels

RS6 (turbo upgrade, wheels)

The S6 won't work (too much work to get the 4.2 upgrade with custom turbo system).

Trying to put together the limiting factors and limits of the above alternatives.