Close

    • The difference a Wagner intercooler and Milltek exhaust make on an Audi TT-RS 2.5 TFSI

      Your basic upgrades on a turbocharged car are the exhaust and intercoolers. These modifications not only improve the efficiency of the stock motor but they pay big dividends when you start pushing a lot more air.


      This TT-RS is on the stock tuning software and was tested by Stertman Motorsport in Sweden.

      Here is the stock pull overlaid with the FMIC (front mount intercooler) and Milltek turbo back exhaust pull:


      Gains through the entire curve but how much of that is the exhaust and how much of it is the intercooler? We wish we knew.

      What we do now is both parts are working well to produce a gain of roughly 26 horsepower and the intercooler will help retain that gain after multiple pulls.

      A good place to start when tuning the 2.5 TFSI.

      This article was originally published in forum thread: The difference a Wagner intercooler and Milltek exhaust make on an Audi TT-RS 2.5 TFSI started by Sticky View original post
      Comments 19 Comments
      1. 135idct's Avatar
        135idct -
        ordered this cooler 3 months ago, soon ill install it
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        ordered this cooler 3 months ago, soon ill install it
        What have you been waiting for?
      1. 135idct's Avatar
        135idct -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        What have you been waiting for?
        ill install it when APR release stg2 tune + dp + cai all same time
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        ill install it when APR release stg2 tune + dp + cai all same time
        Makes sense.

        Why the N54 still in your avatar? Why no thread on your car?

        I know, I know. I'm annoying but it's nice to see people moving on up into newer platforms.
      1. 135idct's Avatar
        135idct -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Makes sense.

        Why the N54 still in your avatar? Why no thread on your car?

        I know, I know. I'm annoying but it's nice to see people moving on up into newer platforms.
        don't like to share(waste of time)
        , they already shared everything.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        don't like to share(waste of time)
        , they already shared everything.
        Click here to enlarge
      1. gaspam's Avatar
        gaspam -
        where is the 26 hp gain figure coming from? I see stock of 343 hp on the graph and 381 hp for IC+exhaust, which is 38 hp gain, what am i missing?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by gaspam Click here to enlarge
        where is the 26 hp gain figure coming from? I see stock of 343 hp on the graph and 381 hp for IC+exhaust, which is 38 hp gain, what am i missing?
        I was reading from the 360 indicated baseline run to the corrected 386 after run.
      1. gaspam's Avatar
        gaspam -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I was reading from the 360 indicated baseline run to the corrected 386 after run.
        isnt that 360 baseline number an uncorrected number? as it looks like on the graph it turns into 343 hp corrected
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by gaspam Click here to enlarge
        isnt that 360 baseline number an uncorrected number? as it looks like on the graph it turns into 343 hp corrected
        Then the gain should be 386-343=43
      1. gaspam's Avatar
        gaspam -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Then the gain should be 386-343=43
        that sounds about right as from what i have seen the gains from IC upgrades have been around 40 hp

        it seems like anything you do to these cars nets at least 40 hp lol as they respond very well to any mods
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by gaspam Click here to enlarge
        that sounds about right as from what i have seen the gains from IC upgrades have been around 40 hp
        I'm just going to leave what I wrote as a conservative estimate until we get more results but 40+ hp from this is phenomenal.
      1. Stockguru's Avatar
        Stockguru -
        Sticky,

        I know you're not doing it intentionally but posts like this are just as misleading as the ones made by the aftermarket companies selling the downpipes. Ever notice why the downpipes for modern Audi platforms are almost always dyno'd on a stock car and never a tuned one? There's a good reason for that! It's because the shops know that their downpipes make good power on a stock car but that there are no appreciable gains on a tuned one. So why do downpipes make good power on a stock Audi but not a tuned one? It's simple... When you remove the catalysts with the stock tune, it results in an overshoot of the boost target. Factory tunes on RS3/TTRS, RS7s, S6s, etc. are very conservative in the boost department as we all know and have seen huge gains with just a tune. The stock TTRS/RS3 makes 19-20psi stock. With just a downpipe and cat delete, they typically make 21-22psi. That's what's responsible for the power gains you see in all the dyno sheets.

        Now once the car is tuned and making almost as much boost as the turbo can put out, such as with most Audi 4.0T tunes and the APR and Iroz/Custom Code tunes for the RS3 and TTRS, the downpipe no longer can provide that additional 2 PSI because the turbo is pretty well maxed out already. This results in the downpipe making no appreciable difference in power. The stock downpipe and cat on these cars flow very very well. Manufacturers have learned that the better they can make those pieces flow while still reducing emissions the better the fuel economy will be. So they put lots of work into making them flow extremely well. It's not like years ago where a downpipe was a sure thing for making more power. Things have changed.

        Now obviously this doesn't apply to every single platform out there as some downpipes and/or cats will be restrictive from the factory. However, it most definitely applies to at least the following latest generation platforms:

        RS3/TTRS
        S6/S7/RS6/RS7/A8 4.0T
        Audi A3 2.0T/S3/Golf R/GTI/TT/TTS

        Lastly, I'll provide with one example to show you what I mean. There are many many other examples. I think a year or two ago you and I discussed this in a 4.0T thread so you can search my username and find that thread if you wish.

        The dyno sheet below is of ns2g8tr's RS3. On this day he tested the IE intake. The 487.1 was with the Iroz/CC stage 2 ethanol tune, Iroz FMIC, catless Iroz DP/mid pipes and a stock airbox. He then installed the IE intake while his car was still strapped to the dyno and put down 509.8 HP.
        Click here to enlarge

        Now here's an RS3 with all stock hardware (stock downpipe and stock FMIC) with just a Stage 1 ethanol tune from Iroz/CC. Same exact dyno, same correction method. As you can see, peak HP is 486, only 1HP away from the Stage 2 car which had the downpipe, mid pipes and FMIC! If you look carefully, you can see that the Stage 2 car does have a slight advantage in the mid range, but from about 5K on up to redline, the two are pretty darn close.
        Click here to enlarge

        Moral of the story: Going Stage 1 and full E85 sounds like the best bang for your buck on the RS3/TTRS. If you're running ethanol and go from Stage 1 to Stage 2 by adding a DP, mid pipes and FMIC, your car may not get any faster. There's other anecdotal evidence supporting the FMIC not making the RS3/TTRS (stock turbo) any faster too as well as evidence pointing to it being susceptible to heat soak (power loss on the dyno from one run to the next). I'd be more than happy to share that with you too.

        It would be great if you could start sharing these sorts of things on your main page, although I realize it could be in direct conflict with some of your advertisers. I think owners have a right to know this kind of thing as it can definitely help them choose the right mod path for their goals.
      1. Stockguru's Avatar
        Stockguru -
        That's weird. Both images were working when I first made the post. Here's the other dyno graph:

        Click here to enlargeClick here to enlarge
      1. Stockguru's Avatar
        Stockguru -
        ....
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Stockguru Click here to enlarge
        There's a good reason for that! It's because the shops know that their downpipes make good power on a stock car but that there are no appreciable gains on a tuned one.
        How does that make any sense?

        If they flow better on a stock car they will show even more benefit when tuned as they alleviate a restriction.

        Click here to enlarge Originally Posted by Stockguru Click here to enlarge
        When you remove the catalysts with the stock tune, it results in an overshoot of the boost target. Factory tunes on RS3/TTRS, RS7s, S6s, etc. are very conservative in the boost department as we all know and have seen huge gains with just a tune. The stock TTRS/RS3 makes 19-20psi stock. With just a downpipe and cat delete, they typically make 21-22psi. That's what's responsible for the power gains you see in all the dyno sheets.
        If you are saying there is a software issues when downpipes are removed that is completely different than saying there is no benefit from a downpipe when tuned.

        There is always a benefit to removing restriction downstream in a turbo car especially when you do a cat delete so close to the turbo. I see it myself in my own testing on my turbo car.

        Software tuning issues on Audi's are not my area of expertise.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Stockguru Click here to enlarge
        It would be great if you could start sharing these sorts of things on your main page, although I realize it could be in direct conflict with some of your advertisers. I think owners have a right to know this kind of thing as it can definitely help them choose the right mod path for their goals.
        Conflict doesn't bother me. What bothers me is that we have mountains of evidence showing stock downpipes being restrictions when tuned.
      1. Stockguru's Avatar
        Stockguru -
        It makes perfect sense. Just like I said, removing the cats adds boost. So on a stock car with stock boost, there will be good gains from the increased boost pressure. Now once the car is tuned on ethanol and the turbo is at or near its limit, no more boost can be made so the aftermarket downpipe can no longer add the same 2psi as before. That is why the downpipe adds no appreciable power. There is a restriction with the stock downpipes/cats; it's just an extremely small one. Like I said, the downpipes and cats flow very very well on a lot of the newest Audi platforms, such as the 4.0T and 2.5T. I can't speak for other makes like BMW or MB though. However back in the day there were solid gains on cars like DSMs, Evos, etc. It's just not the same with new Audis.

        Where's your "mountain of evidence?" Did you see the dyno charts I posted? Same dyno, same correction; both running Custom Code ethanol software.

        If you'd like, I can also provide same day at the dragstrip results for 2.5T cars with a stock downpipe vs with a catless aftermarket one.


        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        How does that make any sense?

        If they flow better on a stock car they will show even more benefit when tuned as they alleviate a restriction.



        If you are saying there is a software issues when downpipes are removed that is completely different than saying there is no benefit from a downpipe when tuned.

        There is always a benefit to removing restriction downstream in a turbo car especially when you do a cat delete so close to the turbo. I see it myself in my own testing on my turbo car.

        Software tuning issues on Audi's are not my area of expertise.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Stockguru Click here to enlarge
        It makes perfect sense. Just like I said, removing the cats adds boost. So on a stock car with stock boost, there will be good gains from the increased boost pressure.
        Why is it adding boost? It should be reducing boost. Is the ECU compensating or something?

        Click here to enlarge Originally Posted by Stockguru Click here to enlarge
        Where's your "mountain of evidence?" Did you see the dyno charts I posted? Same dyno, same correction; both running Custom Code ethanol software.
        Literally every exhaust chart for every turbo motor that ditches cats in history?