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Power lost after installing 3” piping

S T

Passed Driver's Ed
Location
Brunei
After installing a 3” pipes straight through, I’ve noticed a significant loss of power at low end, the powerband is at high rpms at all gears.
Can anyone advise if this is normal with 3”?


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Faceman

Autocross Newbie
Location
Long Island
Car(s)
'17 GSW 4Mo
Do you have a tune?
 

GTI Jake

Autocross Champion
Location
Charlotte, NC
Google “turbo drive pressure”. There’s no sure thing as needing back pressure on a turbo engine. The hot side of the turbo is all the back pressure it needs.

In fact our cars spool so fast the EWG is open at low rpm often to help regulate boost. That’s why these cars usual sound bad cruising around since that that point it’s like being NA.

So, if you feel like you’ve lost power just stop lugging it around. It’s really hard on the bottom end to drive it like a diesel
 

flipflp

Autocross Newbie
Location
PNW
Car(s)
'16 Golf R DSG
I would bet money on butt dyno or just noise affecting your perception of the power curve being much more likely.

Better question, what is this question doing in a Regional Subforum for California, posted by someone from Brunei? hahah
 

S T

Passed Driver's Ed
Location
Brunei
^This I'd figure. Might be a turbo but it's still a 4 cylinder. Without some form of front end compensation (larger turbo, etc.) and/or tune I'd figure 3" straight might be too free flowing.



You are exactly correct there, i shd hv researched this before doing it but ive changed back my setup to a 3” catless dp to 2.5” catback. Power gains at low end came back.
Im stock tune atm only using racechip which i guess is not sufficient evidently.


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S T

Passed Driver's Ed
Location
Brunei
Google “turbo drive pressure”. There’s no sure thing as needing back pressure on a turbo engine. The hot side of the turbo is all the back pressure it needs.

In fact our cars spool so fast the EWG is open at low rpm often to help regulate boost. That’s why these cars usual sound bad cruising around since that that point it’s like being NA.

So, if you feel like you’ve lost power just stop lugging it around. It’s really hard on the bottom end to drive it like a diesel



I’ve changed my setup to 3” dp (which I always had) to 2.5” catback and the power gain came back at low end. Guess it was too much free flow for a stock tune. Needs a tune or a bigger turbo to compensate.


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S T

Passed Driver's Ed
Location
Brunei
I would bet money on butt dyno or just noise affecting your perception of the power curve being much more likely.

Better question, what is this question doing in a Regional Subforum for California, posted by someone from Brunei? hahah



Im sorry is there a restriction on posting in other regions? I like to hear ppls different opinions.


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flipflp

Autocross Newbie
Location
PNW
Car(s)
'16 Golf R DSG
Im sorry is there a restriction on posting in other regions? I like to hear ppls different opinions.


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Regional sub forums are for regional posts, like posts specific to local meets, shops, etc.

Your post would be considered off topic, and would be moved by mods if it was really an issue. I'm not here to be forum police though.

It's just odd, and getting way fewer eyes who would want to answer your question here. Posting in the engine/tune sub forum would just make more sense all around, but you do you.

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S T

Passed Driver's Ed
Location
Brunei
Regional sub forums are for regional posts, like posts specific to local meets, shops, etc.

Your post would be considered off topic, and would be moved by mods if it was really an issue. I'm not here to be forum police though.

It's just odd, and getting way fewer eyes who would want to answer your question here. Posting in the engine/tune sub forum would just make more sense all around, but you do you.

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I did post in there too but only replies i got is here. Sorry I’m still learning in this forum as im new.


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GTI Jake

Autocross Champion
Location
Charlotte, NC
I’ve changed my setup to 3” dp (which I always had) to 2.5” catback and the power gain came back at low end. Guess it was too much free flow for a stock tune. Needs a tune or a bigger turbo to compensate.


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Again this is incorrect regardless of tune. Turbo engines do NOT need nor “want” back pressure from the exhaust. The hot side of the turbo is all the back pressure it’ll ever need as it’s actually causing drive pressure.

Your perception driving the car aka butt dyno is not an actual measurement of performance. Dyno testing would prove you’re incorrect
 

S T

Passed Driver's Ed
Location
Brunei
Again this is incorrect regardless of tune. Turbo engines do NOT need nor “want” back pressure from the exhaust. The hot side of the turbo is all the back pressure it’ll ever need as it’s actually causing drive pressure.



Your perception driving the car aka butt dyno is not an actual measurement of performance. Dyno testing would prove you’re incorrect



I took that advise and went ahead with the installation. Im sure dyno wld say otherwise, it’s just that low end power is less but high end is there. Rpms and every gear wants to maxout before changing gears. I do feel the power on the high end on the highway though. Im mostly city driving so yea low end is pretty much needed. I PMed you about my new setup btw.


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GTI Jake

Autocross Champion
Location
Charlotte, NC
I took that advise and went ahead with the installation. Im sure dyno wld say otherwise, it’s just that low end power is less but high end is there. Rpms and every gear wants to maxout before changing gears. I do feel the power on the high end on the highway though. Im mostly city driving so yea low end is pretty much needed. I PMed you about my new setup btw.


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Any time you remove a restriction it makes the power curve more linear, which may feel less aggressive/powerful but the smoother power is still increased throughout the rpm range.

Another thing to note is that these cars calculate a target TQ not boost pressure, so with less restrictive components you’ll make more power with less boost (boost is also a measurement of restriction).

This is a good thing because the efficiency of the turbo is maxed out at a certain shaft speed, so making 250whp at 20psi is better than making 250hp at 28psi. Of course we know the is20 effective range reaches much higher than 20psi, but just for explanations sake those numbers are just for reference
 
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