GOLFMK8
GOLFMK7
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4" true downpipe

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Doesn't the Trackslag bolt to the stock catback?
If the claims that catbacks offer zero HP gains are actually true, going from 4" to 3" will be far less of a problem than 4" to 2.5".
The Trackslag gradually tapers from 4" down to 3" and then to 2 1/2" catback if that's what you have but most catbacks are 3" until the split and then it's 2 1/2".
 

git_fan

Go Kart Champion
Location
Virginia
Car(s)
2016 GTI
This is only looking at it from a flow aspect… trackslags DP effectiveness (with real world results to back that up) don’t just have to do with this perceived volume of flow from being bigger. the results (spool/power) you are gaining are due to the reduced egts and the scavenging effect that are results of the large internal section directly off the turbo as well and the gradual reductions in size.



To the point of concerns with it going from 4-3 under the car… I think the effect would be negligible as noted above since the temps will already be greatly reduced by that time.
How does scavenging from a down pipe matter when the downpipe is after the turbine? Also, how is the EGT going to be lower?

From what I understand about the affect of turbos on the exhaust gas flow, it's often stated as a ratio of manifold to turbine inlet pressure (TIP). If that ratio is close to one the turbo is flowing exceptionally well, but that is still somewhere around 20-30 psi of pressure that the exhaust gas is flowing into out of the cylinder before passing through the turbine. How is the DP altering that TIP such that scavenging and lower EGTs come into play?
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
You are making a statement about the part transitioning "suddenly"" when there isn't any information to indicate that is the case.
The OP said he was going to run it 4" down to the 3" catback. If he runs a long enough pipe to transition from 4" to 3" it will be okay. But if he uses a very short pipe to go from 4" to 3" it will be nearly sudden.
 

El_bigote_AJ

Autocross Champion
Location
Las Vegas
Car(s)
2019 GTI bunny
How does scavenging from a down pipe matter when the downpipe is after the turbine? Also, how is the EGT going to be lower?

From what I understand about the affect of turbos on the exhaust gas flow, it's often stated as a ratio of manifold to turbine inlet pressure (TIP). If that ratio is close to one the turbo is flowing exceptionally well, but that is still somewhere around 20-30 psi of pressure that the exhaust gas is flowing into out of the cylinder before passing through the turbine. How is the DP altering that TIP such that scavenging and lower EGTs come into play?
Yes
 

El_bigote_AJ

Autocross Champion
Location
Las Vegas
Car(s)
2019 GTI bunny
Use google… it’s quit simple to understand.

I’m too busy actually DOING things to my car and experiencing REAL world results than to play with your troll arm chair TALKING game.

Don’t worry though - my results that I/me/myself benefit from and I/me/myself enjoy can merely be my “opinion” if that makes you feel better😂
 

git_fan

Go Kart Champion
Location
Virginia
Car(s)
2016 GTI
Use google… it’s quit simple to understand.

I’m too busy actually DOING things to my car and experiencing REAL world results than to play with your troll arm chair TALKING game.

Don’t worry though - my results that I/me/myself benefit from and I/me/myself enjoy can merely be my “opinion” if that makes you feel better😂
Would you mind explaining it then if it is quite simple?

I've worked for an aircraft manufacturer, and while we didn't make the engines, understanding how the turbine engines work has been helpful. So in addition to studying turbine engine fundamentals there was the prerequisite thermodynamics and fluid dynamics. The turbine engine and turbocharger operate on the same principles.

Rather than having me start a likely fruitless search on google, (that was probably the point though right?), why don't you take five minutes to give a succinct explanation?
 

mk6'12gti

Drag Racing Champion
Location
Cleveland
Some more pics almost done
 

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Reggie Enchilada

Autocross Newbie
Location
WV
Some more pics almost done
You better get those welds fixed before using that part. Uneven bead and misaligned, especially at the starts and stops plus the hot spots. Look inside and see if the weld permeated the seam like it should have. From those pics, it doesn't look like it will have.

I'm not trying to rain on your parade because I'm sure that you're excited for a new part, but that's just unsafe. Plenty of people have had fires due to broken welds that weren't done properly.
 

mk6'12gti

Drag Racing Champion
Location
Cleveland
You better get those welds fixed before using that part. Uneven bead and misaligned, especially at the starts and stops plus the hot spots. Look inside and see if the weld permeated the seam like it should have. From those pics, it doesn't look like it will have.

I'm not trying to rain on your parade because I'm sure that you're excited for a new part, but that's just unsafe. Plenty of people have had fires due to broken welds that weren't done properly.
Its not done lol hes going to fix a few things so dont worry it will be just fine when its done.
 

Reggie Enchilada

Autocross Newbie
Location
WV
Exactly how many have you seen fail.
Enough to know that wasn't made properly. Mounting bracket isn't fully welded on and the edges weren't beveled or deburred at the very least. The bead at the reduction is uneven and misaligned. Even appears to be missing in one spot. You can see the starts and stops, where the welder sped up and slowed down.

It's obviously been done by hand, so it will never be perfect and that's fine because it doesn't have to be. At the very least it should be done well and that just wasn't. All of those incorrect spots in the bead create weak points that can fail under stress. Once that pipe heats up, it's yield strength goes down. That combined with the weak points increases the chance of failure. I'm sure you know that 1300°+ exhaust gasses shooting into your engine bay is not a good thing.

Hopefully that was an in progress photo during production and not taken by you after receiving it.

At the end of the day, it's your car. I'm just trying to help you spot problems before they become catastrophic failures and burn your car down.
 
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