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Shock horror I am going to play with the 80k car myself

My goal is 1000bhp but not sure I will ever get there. TTE8xx turbos will get me to 800bhp for around 2k. Not got a price for the TTE9xx yet but I hear they are good for close on 1000bhp. Might just go for the 9xx and run 800 until I get the intercooler flow sorted not sure yet.

Inlet Modification

Think I will start with the inlet. Looking at the standard inlet it is very very poor and has got to be choking the engine when upping the power. On my GTR I had 2 x 76mm inlets with HUGE K&N filters I had to modify the bodywork to make fit. Definitely no restriction.

Even the expensive aftermarket airbox has very small intake pipes and one tiny air filter

I think I will go with something like the one with the single filter in the pic but will make a cold air box where the green line is and 2 individual filters and intake pipes. I would also like to increase the size of the intake right to the turbo inlet. Might need a fab shop to help me out. The engine design is good for this type of airbox as all the heat that is generated is kept inside the engine V, making a decent cold airbox should be easy enough. Might even sound good or maybe a bit chavy, wont know until its done I suppose

Don't be shy in letting me if you think its rubbish. All input greatly received.

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Shoppinit wrote:*subscribed*

+2

Exhaust.

Overall the exhaust looks pretty good. double 2.5" system. 5" exhaust is pretty big. I am not big on flow calculations so not sure is 2.5" I enough per side. Again going back to the GTR a Single 4" can flow over 1400bhp. Not sure if that means 2 x 2.5" can flow more. I am sure its not that simple??

Cheap option would be GUT the cats (all 4) and replace the rear boxs. that would give straight through 2.5" system for very little money. Rear box is very poor flow design (you can see how the exhaust flow deadheads again the metalwork then will fill the box before it finds it way out) but good for noise reduction needs changed

Anyway my Plan

3" Catless downpipes. You can buy these separate from Milltek (don't need to buy the 1200 ones or a full system) for 218 each. Wrap them with heat resistant cloth in an attempt to keep engine bay temps down. I did think on getting them coated but there is little research to suggest any real benefit
3" front pipes again catless but will be flanged to allow for easy change when MOT comes round. Local fab shop
Connected to Milltek 2.5" system. I may look for into a fab shop doing me a full twin 3" system

Paul,

I am of similar mindset to you, my input about heatwrap is defintely worth it, my old 400hp Saab 9-5 (if you can remember what the bays look like on those) the downpipe is around 1" away from the intercooler pipe so heat trasfer was a big issues when doing big pulls in 3rd/4th...
Once i'd wrapped the entire downpipe (stopped at the de-cat near the gear selector) and it made a hellish difference, before this i had it ceramic coated and the changes to temps were totally negliable... looked pretty though haha!

I myself will be running 3" downpipes, from a flow perspective im not sure, my 9-5 needed 3" to get the gas out quicker to keep the exhaust temps down, i run a 3" full system on my n/a accord and even that made a good difference power wise higher up.
The setup is effectively 4cyl turbo per downpipe to tip so roughly as possible each bank is going to provide 400hp so if someone can chime in with some flow calcs that would be perfect, but personally i think you'll need 3" to achive your 800hp goal, at least 3" downpipes granted the turbo's arent huge but heat buildup with increased boost will cause issues, EGT's will sore and ecu will back down power to save the turbo's/engine.

thats just my input, i dont know enough to really give a proper answer.

Parts for Cold air feed and heat shield.

Pipework looks pretty neat with that thick joining clips. Can make it just about any angle to fit. Even holes so I can fit temp prob etc.

Dustbin maybe looks a bit cheap and nasty but if nothing else I will be able to make a good template with it and depending how it goes and looks it might end up staying. Runner bead for the top to seal box.

Not looks for air filters yet.

Getting bigger diameter intake pipe is going to be difficult, nothing at all on the net.

Paulm wrote:Exhaust.

Overall the exhaust looks pretty good. double 2.5" system. 5" exhaust is pretty big. I am not big on flow calculations so not sure is 2.5" I enough per side. Again going back to the GTR a Single 4" can flow over 1400bhp. Not sure if that means 2 x 2.5" can flow more. I am sure its not that simple??

Cheap option would be GUT the cats (all 4) and replace the rear boxs. that would give straight through 2.5" system for very little money. Rear box is very poor flow design (you can see how the exhaust flow deadheads again the metalwork then will fill the box before it finds it way out) but good for noise reduction needs changed

Anyway my Plan

3" Catless downpipes. You can buy these separate from Milltek (don't need to buy the 1200 ones or a full system) for 218 each. Wrap them with heat resistant cloth in an attempt to keep engine bay temps down. I did think on getting them coated but there is little research to suggest any real benefit
3" front pipes again catless but will be flanged to allow for easy change when MOT comes round. Local fab shop
Connected to Milltek 2.5" system. I may look for into a fab shop doing me a full twin 3" system

The exhaust setup is the weak point in the RS6, ask a tuner like MRC and they will tell you that the stock system is very restrictive.

I had the full Milltek fitted yesterday and the difference it has made is night and day, I was actually very surprised at the difference it has made, spooling much quicker and punching harder for longer. The noise is superb, I went for the resonated section and glad that I did as it's loud, any louder and I think it would be too much. The videos on YT do not do it justice, the sound in real life and up close is so much better, it sounds like a bloody jet fighter

60hp gains from the exhaust prove that the standard exhaust system is choked with 2 x 2.5 and 4 cats.

Google an image of the standard downpipes, I dont think gutting the primary cats is an option without serious modifications. You would have to cut them open and reweld, not worth it in my opinion. The secondary cats probably a little easier but not convinced it would be worth it. 2 x 2.5' is not the same as 1 x 5, Velocity increases as pressure decreases through a narrower diamater restriction, so through a narrower pipe, velocity will be quicker, but pressure will be lower. EGT temps will therefore be higher being forced through a 2.5 inch downpipe as opposed to a larger diamater pipe. 5 inch pipework I suspect would be quite laggy, too much, turbos need a little back pressure. You need to keep valves in the back boxes for noise control (its very loud and would probably fail trackday noise limits) so straight through pipe back boxes would be a no go if you wanted to keep the RS6 as a comfortable cruiser.

The whole standard system is 2 x 2.5'', The original Milltek system is 2 x 2.75'', the new system now comprises of 2 x 3'' Cerakote coated downpipes flowing through front connecting/2nd cat bypass pipes, again 3 inches and then tapering down to 2.75 inch for the Milltek catback. I'm not sure where you have got your information from Paul reference buying the 3 inch downpipes uncoated and separately but through my own research that is wrong. The 2.75 inch downpipes are uncoated, all 3 inch downpipes are coated. Milltek do not have any 2.5 inch systems?

If you want to go above 750, I would think you would need the 3 inch opening downpipes (for EGT reasons) for Stage 2 power levels upto 750, the 2 x 2.75'' is good enough. The 3 inch downpipes are expensive at around £1350 retail, £1200 discounted. (2.75'' is £450 cheaper than those)

Are you sure on your hybrid figures?

The TTE900 units come in at 12000 Euros for the pair (£8600) for brand new turbos units hybridised. If you remove your units and send them to Simon at TTE, the cost comes down to 7000 euros for the hybrid work (£5k)

I do not know the cost of the TTE800 units but would be mega surprised if he is going to do the hybrid work for £2k (£1k a turbo) - I think he probably means £2k a turbo so £4k? I would get him to clarify that. I know the TTE900 prices are correct so if they are £5k on your used units, TTE800 wouldn't be too far off that? No idea on turnaround time but you would obviously have to remove them, send them, he does the work, sends them back to you and you refit. That process may take a good few weeks with the car being off the road? I think everything is going to be so much more expensive on the RS6 as it was in your GTR, much more captive smaller market.

Not convinced on the intakes, I've not seen anything yet on the 4.0TT that has convinced me to start fiddling around with it.

I look forward to seeing your results though, good luck

Sorry meant Milltek 2.75 system

I have no intension of playing with the standard pipe I was just speaking out loud. I used to gut cats years ago with good results. MRC use to do it as well, probably cheap worthwhile mod every time.

TTE8xx is 2899 euro inc vat for the pair. Confirmed on my 1000bhp thread and on his site if you hit the link.

I wont be going new with the TT9xx I will recon my units way cheaper as above. if the cost is still to prohibitive I will go back to Turbodynamics who did my 900R GTR turbos. they were only 3k

If you do some reading anything around 800bhp needs inlet sorted. There are a few cars out there (including MRC) with bigger inlets but nothing commercial I can find yet to purchase.

No-one is ever convinced changing things will be better that's the fun or R&D. If its rubbish its rubbish, I will just try something else. Looking at the intake it would be hard to make it any worse though

You need to be carful releasing an extra 60bhp with your catless system and not getting it checked over?? running lean would not be good. Should it not be stage 2 remap now??

Yeah will be doing some logging tonight/tomorrow to see what it's doing. Will get it tweaked soon though

Never realised the 800 units were so cheap, there's obviously a lot more work to do on the 900 units. Cost for them seemed bonkers to me. Yes, looks like the charge cooler is the next restriction beyond 750, I see Forge have an RS6 in at the moment for development work. Will be keeping an eye on your intakes progress too

800 unit is only a compressor wheel upgrade.

2.5" exhaust I was seeing 8psi back pressure at 400hp. Bad news. Changed to 3" and <1psi back pressure at 450hp.

This was on a 1600cc engine but airflow is airflow. I'd say 2.5" per bank will restrict heavily IMO.

RossDagley wrote:2.5" exhaust I was seeing 8psi back pressure at 400hp. Bad news. Changed to 3" and <1psi back pressure at 450hp.

This was on a 1600cc engine but airflow is airflow. I'd say 2.5" per bank will restrict heavily IMO.

That's the kind of info I need, actual results. Prefect much appreciated. 3" it is then

Ok so I wont be the first. Found some pics last night. I like the alloy one but cant find where to buy it. I guess the only difference with mine is I will have a heat shield as well. Still think th epipes into the turbos need addressed

With those engines above with 2 air filters, doesn't the one in front restrict airflow into the other bank?

difficult to say, you might have to do some smoke testing. either way not easy to figure out. The top one is the way to go I think and it looks good. If I can actually find it I think that's what I will have