Winter Project: C5 RS6 upgrade

[Avus-RS6]

Sounds like a nice build, thanks for posting. I think you should get close to your power goals if not attain them.

There will be some big power RS6's coming out of WA state very soon, 700-800awhp range. The problem is the engine has to be dropped for just about everything, and it takes two large, expensive turbos to make big power on these cars, and when I say big power, I mean double the stock rating. Not only that, but all the fab work required for headers, downpipes, fuel system, and a new intake as our tiny airbox is restrictive above chipped power. There's not tons of room to stuff those big turbos, and not really worth while until you do a manual swap, yet another large expense. You can get a couple hundred extra ponies and a few hundred extra ft lbs with RS6-K04 based turbos, but to notch it up from there requires much much more time and money. This is why we haven't seen much of this, it's one of the least cost effective Audis to make really big power with. It does start with 450 from the factory, which isn't too shabby, and they put together a tight package that is time and $ to mod. 11 years later, we're finally seeing these cars get pushed as there's a nice handful of manual cars to play with now.

[ben916]

Sounds like a nice build, thanks for posting. I think you should get close to your power goals if not attain them.

There will be some big power RS6's coming out of WA state very soon, 700-800awhp range. The problem is the engine has to be dropped for just about everything, and it takes two large, expensive turbos to make big power on these cars, and when I say big power, I mean double the stock rating. Not only that, but all the fab work required for headers, downpipes, fuel system, and a new intake as our tiny airbox is restrictive above chipped power. There's not tons of room to stuff those big turbos, and not really worth while until you do a manual swap, yet another large expense. You can get a couple hundred extra ponies and a few hundred extra ft lbs with RS6-K04 based turbos, but to notch it up from there requires much much more time and money. This is why we haven't seen much of this, it's one of the least cost effective Audis to make really big power with. It does start with 450 from the factory, which isn't too shabby, and they put together a tight package that is time and $ to mod. 11 years later, we're finally seeing these cars get pushed as there's a nice handful of manual cars to play with now.

Off Topic:
Care to share the location of this big power build??? whom???

[lswing]

Off Topic:
Care to share the location of this big power build??? whom???

Guessing AMD....here's a pic of one of our blocks that's been upgraded, along with custome headers and bigger turbos, going into a A4 stripped frame I think. Just from some Facebook posts, was hearing numbers like 800 cHP I think...race car! Thread jack complete!

[ben916]

Guessing AMD....here's a pic of one of our blocks that's been upgraded, along with custome headers and bigger turbos, going into a A4 stripped frame I think. Just from some Facebook posts, was hearing numbers like 800 cHP I think...race car! Thread jack complete!

Lovely time to dyno the motor!
Anyone got 100 miles of sensors and a couple of MAFs and O2 sensors, and cam tensioners and and and and..................

I would LOVE to see someone get bigger snails on 4.2 lump in the C5 RS6 (not the Gumpert)

[Korben007]

The reason it's so hard to get over 600 chp is because of the plumbing. The headers are just to small!

[Turbowned]

I'd like to think that by the time I pay off this car I'll be in a position to build it up for big numbers... but then it becomes a matter of "do I spend a ton of money on an old car or do I just buy a better car for the same amount I would've spent?"

At least that's what I'm running into with the BRZ; I could've bought myself a nice gently used E92 M3 or 997 Carrera S for the money I've spent on this foolish Subaru

[DHall1]

Who needs a firewall.

Hell just strap a seat on that bad boy and take er for a ride

Guessing AMD....here's a pic of one of our blocks that's been upgraded, along with custome headers and bigger turbos, going into a A4 stripped frame I think. Just from some Facebook posts, was hearing numbers like 800 cHP I think...race car! Thread jack complete!

[DHall1]

Primary reason my mod list stays in check. I dont ever go insane on builds just to say my car ran this or that or put down a dyno.

I just build to tweek a few driving specs and make my boring commute spicy.

I'd like to think that by the time I pay off this car I'll be in a position to build it up for big numbers... but then it becomes a matter of "do I spend a ton of money on an old car or do I just buy a better car for the same amount I would've spent?"

At least that's what I'm running into with the BRZ; I could've bought myself a nice gently used E92 M3 or 997 Carrera S for the money I've spent on this foolish Subaru

[Bigglezworth]

Yet another post about someone getting ready to labotamize the 4.2 and inject more money than makes sense to many trying to extract more power out a 2 ton tank. Sorry to the OP, but this post isn't the first time we've seen these 'desires' and it won't be the last. Best of success with whatever you end up doing. No matter what you choose you will find your wallet significantly lighter, and be eating up other weaker links in the chain as a result. Why wouldn't you want to put all this time and money in to a car that can benefit better from your labour of love?

[vtraudt]

RS6 (according to post) have fairly weak wastegate actuators.
Add to it the expected high back pressure, and controlling boost at high rpm might become an issue (wastegate getting pushed open).
I have not found suitable upgrade actuators. Is the only solution to fabricate custom ones (10 or 12psi or 1 bar)? Any suggestions?

[Korben007]

I boost about 11 psi on wastegate pressure with k03 waste gates

[lswing]

I boost about 11 psi on wastegate pressure with k03 waste gates

That is 11psi wastegate pressure compared to ~6psi stock wastegate pressure just to confirm. What are your actual/specified boost numbers?

Any chance you've got a dyno readout to see how the boost holds compared to stock wastegates? Stock wastegate seems to allow boost to hold strong at 15-20 psi (depending on tune settings) until 4,500 RPM's, which is typical.

[vtraudt]

That is 11psi wastegate pressure compared to ~6psi stock wastegate pressure just to confirm. What are your actual/specified boost numbers?

Any chance you've got a dyno readout to see how the boost holds compared to stock wastegates? Stock wastegate seems to allow boost to hold strong at 15-20 psi (depending on tune settings) until 4,500 RPM's, which is typical.

Did the K03 actuators bolt up (both sides) to the RS6 turbos?
K03 from 1.8T longitudinal (for example AEB, AMB, or similar)? I thought the RS6 geometry is 'special' and no other (donor) actuators fit.

[lswing]

For reference, 80 degree day, approximately 15-17psi tuned (depending on conditions), stock wastegates (I think, it's possible the guy at Scroll turned the arm once to stiffen it up, forget). The taper of boost around 4,500 rpm seems very common from the charts I've seen for most every tuned RS6. To hold boost to redline, or close, would be sweet.

[vtraudt]

Looks typical. Need to dig out the stage 1 (stock everything) log.
And yes, want to sustain slightly higher boost to redline with the turbos we built. But clearly, at high flow (and corresponding higher exhaust flow and backpressure (have downpipes though), we expect much higher backpressure. And with the weak RS6 stock wastegate springs, expect the wastegate getting pushed open (backpressure) at high boost, high rpm. Hence: would like to see 12 psi or so crack pressure actuators, but can't find or can't figure out if some 'take offs' (other models) can be used.

[vtraudt]

Found the mild stg1 log (3rd gear):

[lswing]

Yep, 3rd gear also, closest 1:1 ratio. Looks like boost tapers just where torque typically does. You could always call Scroll. I hadn't looked into it much at the time, and was in a hurry or might have increased the wg pressure.