TurboXS Dump Pipe and Recode Tuning for Golf R

[Corey_R]

Thanks Tim, that's a great shot. It shows perfectly the turbo opening and the waste gate opening, and hopefully displays why the concept of a divorced downpipe exists.

I'll leave it to the engineers to argue about which is better, but you can clearly see that the "red marked areas" drawn onto the pictures above are not representative of how the turbo lines up to the downpipe.

[Tim]

yeah exhaust gas flow can get pretty technical.
Are there any better pics of the APR setup? It does appear that there is only a very small elliptical opening for the main exhaust gas pipe and that preference is given to the wastegate side of the turbo exit? Im thinking that maybe the black area in the picture above might not show the full story? Always interested to learn some of the theory involved.

[zbeasty]

Haha WTF is with that? Seems like half of it is blocked up!

They have to drop the front subframe to do the DP yeah?

No need to drop the subframe just remove the tailshaft.

[Corey_R]

yeah exhaust gas flow can get pretty technical.
Are there any better pics of the APR setup? It does appear that there is only a very small elliptical opening for the main exhaust gas pipe and that preference is given to the wastegate side of the turbo exit? Im thinking that maybe the black area in the picture above might not show the full story? Always interested to learn some of the theory involved.

Yeah, exhaust flow is certainly WAY beyond my mathematical and physics skills. Just mentioning the topic to the old kart builder behind me has sent him raving about completely being able to dramatically change the torque and HP characterists of an engine by changing the size and shape of the plenum in their exhausts etc.


The photos above aren't too bad, apart from the APR already being soiled by exhaust deposits. The exhaust opening is elliptical, but it has the metal protrusion (seen best in the first two photos) which goes into the turbo's "mouth" to "guide" the exhaust flow from the turbo into the downpipe as early as possible.

The APR exhaust show is specifically for the VW K04.
If you swap to the Garret GT2781R in a Stage 3 kit for example, the divorced design changes to this:


But then that's cause the physical turbo and the placement of the wastegate etc is different.


There was some really good "essays" on this topic in some Subaru forums a few years back, as "divorced vs bellmouth" is also a differentiator between several of the WRX/STI aftermarket designs, but I can't find it right now. Maybe there is some other article about the thoughts behind both designs.

[zbeasty]

yeah exhaust gas flow can get pretty technical.
Are there any better pics of the APR setup? It does appear that there is only a very small elliptical opening for the main exhaust gas pipe and that preference is given to the wastegate side of the turbo exit? Im thinking that maybe the black area in the picture above might not show the full story? Always interested to learn some of the theory involved.

You are correct Tim, there is only the elliptical opening for the main exhaust gas to flow through. The black part between the 2 openings is flat and does not open to anywhere. There is no effective way on the K04 to separate the flow from the turbine and wastegate without compromising the flow of one or the other. In this case the main outlet size is reduced. That is why the red cirle is there on the front on shot. Not only is the opening reduced in size, because the pipe on the other side hasn't been shaped to fit the flow out the other side will just tumble out creating turbulence which will further inhibit flow. You can see the reduction in efficiency in the dyno charts where the APR pipe drops of rapidly after making peak power whereas the TXS one holds power to change up.

TXS have 2 hand made units and have just received their production units. If you're interested give them a call.

[Tim]

Thanks for clearing that up. I was having trouble making out the detail in the photo. The GT28 setup looks very different

[zbeasty]

Thanks for clearing that up. I was having trouble making out the detail in the photo. The GT28 setup looks very different

Sorry, not the best camera or lighting. Yes the divorced wastegate pipe can work on some turbo's like the GT28 but on the K04 the compromise on ultimate flow outweighs the gains from the separation.

[Lazarus7]

Anyone got a pic of the Milltek one for comparison? I've had a search around but can't seen to find one

[Corey_R]

The reason you can't find a picture of the Milltek down pipe is that they don't sell it individually. You need to buy the entire TBE.

You get better results searching for "Audi S3" though, since the DP portion is the same. The new part on the Milltek R exhaust is the catback section, so no one seems to care about taking photos of anything other than the rear muffler and black tips!


Note, this is a catless verison.

[CarbonVW]

An interesting video on the subject. Obviously, every turbo is designed differently and turbulent flow may not be as pronounced compared to other turbo designs.