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Downpipe replacement on a 60k+ mile ST

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#1
Hey guys, my new replacement downpipe has arrived , and I'm looking to install it within the next week. I am hesitant to begin the install because of the horror stories I've heard where downpipe to turbo studs break or round off. My car is higher mileage and I feel like it's extremely likely this will happen when I attempt to remove the stock downpipe. I need my car to commute to technical training for my apprenticeship in the weekday, and a broke n stud, O2 sensor would pretty much screw me over. I was wondering if anyone has experience in the install process and if applying penetrant to the sensors and studs would eliminate the issue of broken components. Thanks.

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Rocketst

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#2
When I replaced my downpipe at 12k miles I didn't see an issue with studs but I did have to cut the connector off my o2 sensor because it was so tight and the tool too shallow that it couldn't turn the sensor. That was the lower one which I believe sat in the heatshielding. I took that heatshielding off because it was a pain in the ass and left it off for future maintenance. My recommendation is when you replace your downpipe replace the studs from the turbo with good quality studs. Whoosh sells some arp locking studs and they are really good quality. I bought them for my car. Also, put some nickel anti seize on the threads and you should be good. Copper is too low heat you need something more extreme. Nickel is good for about 2000 degrees. As for getting the old stuff off, use penetrating oil. Let soak for a good couple of hrs and try to turn it. If it doesn't come off, try again. If it still won't come off, soak with penetrant let sit for as long as you can and put a propane or map gas torch as close to the threads to heat them. They should expand allowing you a little more wiggle room and may free it. This may cause a fire but when the oil runs out it should go out as well. Take care not to hit the connector with the flame.

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TyphoonFiST

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#3
It's a crap shoot. I removed my Stock Dp with no broken studs at 45k...but encountered a cross threaded O2 sensor from the factory. Just be ready and have the tools and extra parts....you can always return what you don't use.

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#4
My turbo to downpipe nuts broke free easily, had not trouble. However my downpipe to catback ones were beyond crossthreaded/seized, took several hours with grinder/air hammer to get them off. Penetrate will help, but it works best if you got time for it. Go ahead and spray all the nuts/bolts now. Then maybe again in a day. And so on for a few days until you go to actually take them off.
 


MagnetiseST

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#5
Penetrate will help remove the bolts, but let me ask you this: Why are you even replacing the downpipe? Failure? Catless? If the answer is catless, you are likely wasting your time / money unless you are looking to make your car louder.

The catless downpipes on our cars don't make them any faster than the stock, Ford actually did a great job on matching up the exhaust size and turbo. You may even lose some torque with the catless downpipe.

My opinion for stock turbo cars is to leave the stock downpipe alone until you swap the turbo, since there is 0 performance benefit.
 


CarGuy

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#6
You actually lose power on a stock turbo going catless per Adam Brunson of TunePlus.

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JDG

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#7
Penetrate will help remove the bolts, but let me ask you this: Why are you even replacing the downpipe? Failure? Catless? If the answer is catless, you are likely wasting your time / money unless you are looking to make your car louder.

The catless downpipes on our cars don't make them any faster than the stock, Ford actually did a great job on matching up the exhaust size and turbo. You may even lose some torque with the catless downpipe.

My opinion for stock turbo cars is to leave the stock downpipe alone until you swap the turbo, since there is 0 performance benefit.
This is the answer. And then when you upgrade the turbo you can move to an upgraded catted downpipe with a 200 cell cat that won't throw emission codes.
 


MagnetiseST

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#8
This is the answer. And then when you upgrade the turbo you can move to an upgraded catted downpipe with a 200 cell cat that won't throw emission codes.
I regret not going catted. But i got such a good deal on a catless CP-e
 


OP
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Thread Starter #9
I just bought a used x37, so im going hybrid turbo by the end of the month :):). I got a good deal on a catless so thats what I went with. I had a limited budget for this car and have bought used parts for this build almost exclusively. I have spent $3600 and went from a stock car to now a hybrid turbo car with full bolt ons, accessport, coilover suspension, 6 point brace, motor mount, rear sway bar and torsion brace, and Delta Styling wing riser! These cars are an absolute bargain! Thanks for the suggestions fellas, now with the unexpected turbo purchase the only thing i have to worry about is seized 02 sensors.
 


JDG

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#10
I just bought a used x37, so im going hybrid turbo by the end of the month :):). I got a good deal on a catless so thats what I went with. I had a limited budget for this car and have bought used parts for this build almost exclusively. I have spent $3600 and went from a stock car to now a hybrid turbo car with full bolt ons, accessport, coilover suspension, 6 point brace, motor mount, rear sway bar and torsion brace, and Delta Styling wing riser! These cars are an absolute bargain! Thanks for the suggestions fellas, now with the unexpected turbo purchase the only thing i have to worry about is seized 02 sensors.
That's fair. What I would do is having some good quality drill bits and a cordless drill on hand with a couple batteries. If you break a bolt, have spares and be ready to drill.

Not a huge deal. Buy some quality penetrating oil like PB blaster and go to town. Then wait 30 minutes, spray again, and then wait 10 minutes. Try to break the bolts loose after that.

**Make sure you do not remove the oil feed line for the turbo that is bolted to the engine block. A lot of folks have mistaken this bolt for one of the heat shield bolts that needs to get removed and ended up blowing that oil line upon running their car again after install. This has led to people running their engine dry or in the case of one guy, a fire.
 


MagnetiseST

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#11
**Make sure you do not remove the oil feed line for the turbo that is bolted to the engine block. A lot of folks have mistaken this bolt for one of the heat shield bolts that needs to get removed and ended up blowing that oil line upon running their car again after install. This has led to people running their engine dry or in the case of one guy, a fire.
He will have to do this to change the turbo
 


Rocketst

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#12
He will have to do this to change the turbo
When you change the turbo make sure you buy a new gasket for the oil line as well as new crush washers for the coolant lines. You'll also want 2 new fire rings, they are 2 different sizes. Small one goes between manifold and turbo large one goes between turbo and downpipe. Also a new gasket for the downpipe to rest of the exhaust.

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jeff

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#13
Replaced my DP at 20,000, upside bolts to turbo were fine but one downside bolt to the exhaust was crossthreaded. So like others said, there's no guarantee here and the best thing to do is have (1) spare parts on hand (2) plenty of time.

Penetrate will help remove the bolts, but let me ask you this: Why are you even replacing the downpipe? Failure? Catless? If the answer is catless, you are likely wasting your time / money unless you are looking to make your car louder.

The catless downpipes on our cars don't make them any faster than the stock, Ford actually did a great job on matching up the exhaust size and turbo. You may even lose some torque with the catless downpipe.

My opinion for stock turbo cars is to leave the stock downpipe alone until you swap the turbo, since there is 0 performance benefit.
You actually lose power on a stock turbo going catless per Adam Brunson of TunePlus.

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Back in 2015ish what Adam proved using real dynos was that on stock turbo the DP upgrade added low end power (what you don't need due to lack of traction) but stole some top end power (what you need on stock turbo).

So yes on stock turbo DP is a waste, but with your X37 upgrade it will be helpful.

Good luck!!!
 


CarGuy

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#14
Replaced my DP at 20,000, upside bolts to turbo were fine but one downside bolt to the exhaust was crossthreaded. So like others said, there's no guarantee here and the best thing to do is have (1) spare parts on hand (2) plenty of time.




Back in 2015ish what Adam proved using real dynos was that on stock turbo the DP upgrade added low end power (what you don't need due to lack of traction) but stole some top end power (what you need on stock turbo).

So yes on stock turbo DP is a waste, but with your X37 upgrade it will be helpful.

Good luck!!!
Not enough to ever need or notice for daily street driving considering the 100% of the time polluting.

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OP
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Thread Starter #16
I appreciate the help fellas. I'd like to avoid the catless vs catted discussion again, there's opinionated views on each side of the argument :)

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OP
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Thread Starter #17
Got everything installed, broke the secondary o2 sensor getting the stock downpipe out but other than that no issues with studs. The biggest thing I can recommend to someone who is going to do this on a higher mileage car is to use oxy acetylene. I had to heat up all the manifold studs, downpipe studs, o2 sensors, manifold to turbo studs and even the damn wiper arms with my oxy acetylene in order to properly remove them without breaking stuff. Unless you soak the stuff for hours and cycle the nuts back and forth until they eventually come off, penetrant isn't going to cut it . I'm a refrigeration technician so I have one in my tool kit, but for those that dont I would recommend investing in a set. When working on cars there are absolutely times where you will need it to remove siezed components. Without it this job would have been an absolute bitch to do as everything was heat soaked and didn't want to come off, and I would have probably broken alot of studs in the process.

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