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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Sometimes you win with ebay gambles, and sometimes you lose. Chinese DPs



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      05-17-2019, 11:00 PM   #1
srey
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Sometimes you win with ebay gambles, and sometimes you lose. Chinese DPs

I tried to save a few bucks and bought Chinese downpipes. I've had good luck with my Chinese chargepipe, so I rolled the dice. The fitment wasn't good. I used the BAH method and have them fitting now without any contact on the subframe, etc. The worst was clearing a bolt on the engine for the inside downpipe. I had to pound the heck out of that one. The picture looks a million times worse than it really is, though. If they don't end up working for me I'll shell out for some VRSF pipes. I have their inlets and 7" HD FMIC, and have been happy with their fitment.

Like I said, I'm rolling with them and expect them to perform fine, but I'm posting this here as both a cautionary tale and to take any lumps y'all might want to dish out.



*Edit: I'm not worried about the welds at all. They're solid as. Even though parts look folded and creased, it's smooth inside. The pipes are real stainless steel too, as confirmed by a magnet.
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      05-18-2019, 04:47 PM   #2
woodex m.e.
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Just an educational comment. Magnet testing alloys does not really tell you very much. Stainless steels come in magnetic and non magnetic forms.

Also there are MANY forms of stainless and they are not at all created equal in terms of quality.
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      05-18-2019, 07:19 PM   #3
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Quote:
Originally Posted by woodex m.e. View Post
Just an educational comment. Magnet testing alloys does not really tell you very much. Stainless steels come in magnetic and non magnetic forms.

Also there are MANY forms of stainless and they are not at all created equal in terms of quality.
Makes me wonder, without doing research I would expect these to be 304 stainless and there would be be some magnetic pull with 304.

If they fail, it will be the welds, not new and under the hammer but after a few hundred heat cycles.
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      05-18-2019, 07:47 PM   #4
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We'll see how they hold up. Here they are installed. You can see the clearance on that bolt as well as the subframe clearance.



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      05-19-2019, 04:40 PM   #5
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Quote:
Originally Posted by rjahl View Post
Makes me wonder, without doing research I would expect these to be 304 stainless and there would be be some magnetic pull with 304.

If they fail, it will be the welds, not new and under the hammer but after a few hundred heat cycles.
True grade 304 stainless steel would have no magnetic feel. 17-4 on the other hand would have a noticeable pull. They have very very similar corrosion characteristics though. Structurally speaking not sure how 17-4 would hold up because technically you can change the strength properties by cycling through various temperatures with the exhaust.

So many alloys, so little time.
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      05-19-2019, 04:42 PM   #6
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Originally Posted by srey View Post
We'll see how they hold up. Here they are installed. You can see the clearance on that bolt as well as the subframe clearance.



I hope these things work great for you. Cheap stuff that functions just as awesome as expensive stuff is always a bargain we should be looking for.
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      05-20-2019, 09:58 AM   #7
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Quote:
Originally Posted by woodex m.e. View Post
Quote:
Originally Posted by srey View Post
We'll see how they hold up. Here they are installed. You can see the clearance on that bolt as well as the subframe clearance.



I hope these things work great for you. Cheap stuff that functions just as awesome as expensive stuff is always a bargain we should be looking for.
hammering pipes to make them fit doesn't count lol.
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      05-20-2019, 03:57 PM   #8
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hammering pipes to make them fit doesn't count lol.
Agreed. In hindsight it wasn't worth the savings, and that's with a diy. If I was paying someone I would have gone a different route.
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      05-20-2019, 04:05 PM   #9
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Even worse if RWD, AWD is a bitch in of itself. They fit so perfectly that if they aren't placed in orientated 100% correctly and correct order, they won't go in.
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      05-20-2019, 07:08 PM   #10
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i recall you are the same guy that was proponent of Chinese turbo too! hah.

Austenitic SS is fine for exhaust. Ferritic SS can be a problem

Welds might be okay now, but give it few thousand miles
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      05-20-2019, 07:49 PM   #11
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Quote:
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i recall you are the same guy that was proponent of Chinese turbo too! hah.

Austenitic SS is fine for exhaust. Ferritic SS can be a problem

Welds might be okay now, but give it few thousand miles
Not a proponent, just interested in their potential viability as a budget option. I wouldn't actively advocate for a product I wasn't personally running. It's all good, though.

The manufacturing on these pipes looks good. It's just the fit that's off. I bought vrsf for my inlets and fmic. When I do turbos I'll probably go name brand with those too. I tried these pipes because I figured they were worth a gamble. I'm confident in my wrenching ability, so the only cost would have been time. I have a beater I can drive while the 335i is on jackstands, so it was a calculated gamble. I lost, and that's ok. I'm hoping by sharing my op that it will help others who are looking for cheap options. The forums are full of guys saying don't by generic products, but not as many that actually share experiences with them. In a way this thread is part of my penance.
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      Yesterday, 02:59 PM   #12
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my NNQ catless didn't fit. Cost me $$ as I was having stuff done all at once, and it wasted my indy's time. They were cool about it but I can tell slightly irritated [here I am bringing in my parts that dont fit ] ..

TBH after researching all the hassles with DP fix, noise, smell etc, I will just save up the $$ and get some good catted [Turner or CPe] . ATM I have factory catted dps <-> secondary with Borla S type catbacks. Sounds nice but some drone. Once I get the catted DPs I may go with some small resonators in place of the factory secondary cats. I think that solution may give a better result than catless DPs [also no funky dp fix needed etc.]

Just my thoughts.
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