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      07-29-2013, 12:14 PM   #1
dhirm5
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Downpipes

Given that the downpipes on turbo cars are really just a piece of pipe with a couple bends in them, wouldn't it be cost effective to go to a good custom exhaust shop with a mandrel bender and have them fabricate something? High flow cats can be had for next to nothing:

http://www.mandrelbendingsolutions.c...,-High,/Detail

A downpipe should be a few hundred at most plus install time. What am I missing - why are these being sold for up to 3k for the F10 M5?
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      07-29-2013, 01:59 PM   #2
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Completely agree with you. I used to get dp's fabricated at my friend's shop for turbo imports. Parts cost next to nothing and labor is the same. Each of these pipes, if catless, doesn't cost more than $200 to fabricate.
To companies' defense, margins on parts are so small that in order for them to survive they have to look for markets and products they can make up their margins on from less profitable sales.
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      07-29-2013, 02:36 PM   #3
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      07-29-2013, 04:31 PM   #4
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Quote:
Originally Posted by dhirm5 View Post
Given that the downpipes on turbo cars are really just a piece of pipe with a couple bends in them, wouldn't it be cost effective to go to a good custom exhaust shop with a mandrel bender and have them fabricate something? High flow cats can be had for next to nothing:

http://www.mandrelbendingsolutions.c...,-High,/Detail

A downpipe should be a few hundred at most plus install time. What am I missing - why are these being sold for up to 3k for the F10 M5?
I had MBS custom fab a catback exhaust for my old CTS-V (it actually droned to the point of giving me a headache) and before that they did a muffler delete for my old CL65 (which added a little bit more sound but no noticeable drone ).

The problem with the cats on the M5 is the tight space you have to work with in the downpipe area. The placement of the O2 sensors are pretty close to the inlet. The off the shelf catalytic converters will not fit in that area. I would also not recommend anything below 200 cells as you are likely going to trigger the CEL. You could try to use a "micro cat" up top to stop the CEL issue for a catless downpipe and then put two off the shelf catalytic converters down stream where there is more space (Supersprint has a set up like that but at an astronomical $ amount).
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      07-29-2013, 09:46 PM   #5
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Quote:
Originally Posted by Tom C View Post
I would also not recommend anything below 200 cells as you are likely going to trigger the CEL.
+1
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      07-29-2013, 10:01 PM   #6
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Quote:
Originally Posted by Tom C View Post
I had MBS custom fab a catback exhaust for my old CTS-V (it actually droned to the point of giving me a headache) and before that they did a muffler delete for my old CL65 (which added a little bit more sound but no noticeable drone ).

The problem with the cats on the M5 is the tight space you have to work with in the downpipe area. The placement of the O2 sensors are pretty close to the inlet. The off the shelf catalytic converters will not fit in that area. I would also not recommend anything below 200 cells as you are likely going to trigger the CEL. You could try to use a "micro cat" up top to stop the CEL issue for a catless downpipe and then put two off the shelf catalytic converters down stream where there is more space (Supersprint has a set up like that but at an astronomical $ amount).
Fair enough. But my point stands. This is a tube. Throw in an ots high flow cat - 200 cell - whatever - towards the end of the pipe - extend the O2 sensor cable harness, and you're done for a few hundred bucks.

The current pricing is ridiculous to say the least.

A good set of headers for the E60 M5 was 3k. There at least it made some sense - that's a very complex set of tubing all interwoven and coming together in a collector which takes real skill to fabricate.

A downpipe?? It's a fucking tube for christ's sake.
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      07-29-2013, 10:21 PM   #7
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I understand how you feel but from experience let me tell you the AMS Alpha DP is a work of art. Smooth bends, high quality cat, perfect fitment with factory mounts in a really tight space. No way a basic shop could do this without a hack job. Also cutting into O2 sensor cables is not a good idea. Swapping them out for longer Bosch sensors with a quick connector change and running the wires through the factory clips is the only way to go. It gets extremely hot in that tight space hot enough to melt the wires. If you want quality fitting of a M5/M6 then spend the money. I spent 3000 and have the 300 cell metal cats, plus 300 for new longer sensors and ceramic coating and let me tell you no CEL and every mechanic in my shop was drooling. This is not a mustang GT, this is a high end German performance machine. I see so many people dropping 6-8k on wheels, the DPs are the REAL deal.

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      07-29-2013, 10:48 PM   #8
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It's not as easy as you think.

First off the metal in the downpipes have to be high enough quality to withstand the extremely high exhaust temperatures coming from the engine. The measurements from the turbo to the sleeve on the exhaust have to be perfect also. The O2 sensor positions also should be in the same exact positions as the stock downpipes. If you've ever seen how the O2 sensors protrude through multiple layers on top of the downpipe, you'd know that this is important.

How do I know this? Because I actually had a local shop in Socal make my downpipes for me custom. With manufacturing, ceramic coating and install, it still cost north of a couple thousand. The downpipes in the F10 M5 are not something that can be easily replicated and thrown in like the downpipes on a Honda civic or something like that. Besides, why would you want a poor quality piece of pipe inside of your $100K car??? If you are looking for cheap mods, then you should stick with CTS-V's, and Corvettes.
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      07-29-2013, 11:07 PM   #9
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Quote:
Originally Posted by RPiM5 View Post
Besides, why would you want a poor quality piece of pipe inside of your $100K car??? If you are looking for cheap mods, then you should stick with CTS-V's, and Corvettes.
Really? So unless I drive a CTS-V or a Corvette, I should just accept that I have to pay 3x - 5x more for a set of pipes?

Sorry - I don't agree with this. A 304 stainless tube is a 304 stainless tube - no matter what company fabricates it. Yes, the welds are important. Any decent shop knows how to do a good weld. It is not rocket science.

Bottom line, we are paying a significant premium. I may have the means to pay 3k, but that doesn't make it any less annoying knowing that the product ought to cost 1k at the outside.
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      07-29-2013, 11:23 PM   #10
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Quote:
Originally Posted by RPiM5 View Post
It's not as easy as you think.

First off the metal in the downpipes have to be high enough quality to withstand the extremely high exhaust temperatures coming from the engine. The measurements from the turbo to the sleeve on the exhaust have to be perfect also. The O2 sensor positions also should be in the same exact positions as the stock downpipes. If you've ever seen how the O2 sensors protrude through multiple layers on top of the downpipe, you'd know that this is important.

How do I know this? Because I actually had a local shop in Socal make my downpipes for me custom. With manufacturing, ceramic coating and install, it still cost north of a couple thousand. The downpipes in the F10 M5 are not something that can be easily replicated and thrown in like the downpipes on a Honda civic or something like that. Besides, why would you want a poor quality piece of pipe inside of your $100K car??? If you are looking for cheap mods, then you should stick with CTS-V's, and Corvettes.

dhirm5 is right in this case. 304 stainless is all the same material. All the bends made out of 304 stainless can be purchased pre-made and it's a common practice for all the companies when exhausts or dp's are being designed. The dp's on our cars are very easily replicated because the bends and design are not complicated, same with the flanges. You use a simple drill, to drill a hole for the o2 bung and you weld the $5 bung. Welds are very important and dependent on the skill of the person, but it doesnt take hours to do. My 304 stainless downpipe with a custom 5 bolt flange and additional outlet for the wastegate dump cost me $350 and it lasted hundreds of dyno runs, even more track runs and street runs and the car was doing 900 whp+ on a Mustang dyno. This was a turbo import running 45 psi on a GT42R turbo and EGT's were much higher than what we are experiencing on the f10s'.
Not to deal with any downtime I just ordered a set of "expensive" downpipes and will have my fabricator guy make copies with the option of a microcat.
I will definitely let you know what the estimate runs, but based on my conversation with him it will be much less than what we pay for.
Not trying to prove a point, but just because our cars are $100k it doesn't mean we have to pay a premium for the same metal and welds.
It's like telling Coca-Cola that they have to pay 5 times more per empty can than Shasta Cola even though they can both hedge the price of aluminum and same exact cans come out.
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      07-30-2013, 08:30 AM   #11
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Quote:
Originally Posted by dhirm5 View Post
Fair enough. But my point stands. This is a tube. Throw in an ots high flow cat - 200 cell - whatever - towards the end of the pipe - extend the O2 sensor cable harness, and you're done for a few hundred bucks.

The current pricing is ridiculous to say the least.

A good set of headers for the E60 M5 was 3k. There at least it made some sense - that's a very complex set of tubing all interwoven and coming together in a collector which takes real skill to fabricate.

A downpipe?? It's a fucking tube for christ's sake.
I don't disagree and have never been one to just acquiesce to premium product pricing for essentially the same quality of product. I think you are on to something. Maybe it is worth a shot taking my car to MBS to fabricate a "catless" downpipe and use these:

http://www.bigdaddiesgarage.com/mini-cat-cel-fix.html

That should solve the CEL issue. Then put an off the shelf 100 cell racing catalytic converter down stream to deal with the environmental/smell issues. There seems to be plenty of room in the front pipes coming down from the down pipes. The biggest problem with aftermarket catalytic converters is that they are not as resistant to the heat generated from turbo cars as the OEM ones. Time and again they melt the internals and you need to replace them more frequently than OEM. If you move the race cats downstream, they aren't subjected to as much intense heat and may last longer.
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      07-30-2013, 08:41 AM   #12
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Quote:
Originally Posted by Tom C View Post
I don't disagree and have never been one to just acquiesce to premium product pricing for essentially the same quality of product. I think you are on to something. Maybe it is worth a shot taking my car to MBS to fabricate a "catless" downpipe and use these:

http://www.bigdaddiesgarage.com/mini-cat-cel-fix.html

That should solve the CEL issue. Then put an off the shelf 100 cell racing catalytic converter down stream to deal with the environmental/smell issues. There seems to be plenty of room in the front pipes coming down from the down pipes. The biggest problem with aftermarket catalytic converters is that they are not as resistant to the heat generated from turbo cars as the OEM ones. Time and again they melt the internals and you need to replace them more frequently than OEM. If you move the race cats downstream, they aren't subjected to as much intense heat and may last longer.
Good call - and nice find on these mini cats - that would def work. Def like the idea of putting in the 100 cell on the straight section far from the motor.

I had a brief interaction with MBS on this - they would need a set of OEM DPs to work off of - might be worth buying a used set - maybe from a board member who has already swapped theirs - and sending them to MBS.

We could probably get a group going to sweeten the deal for them (and us).

BTW - he said they wouldn't be able to use the mandrel bender to make these - not enough straight section between the bends. They'd have to weld - which is fine - MBS is the best around here - I trust they know how to weld.
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      07-30-2013, 08:57 AM   #13
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Theoretically, I agree with the OP. What confuses and concerns me is that one owner I know had DPs manufactured from scratch and had a number of engine misfire problems. Owners of the AMS downpipes have not experienced these issues, or at least are not admitting it.

So apparently, design quality of these basic pipes does matter.
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      07-30-2013, 09:17 AM   #14
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Quote:
Originally Posted by dhirm5 View Post
Good call - and nice find on these mini cats - that would def work. Def like the idea of putting in the 100 cell on the straight section far from the motor.

I had a brief interaction with MBS on this - they would need a set of OEM DPs to work off of - might be worth buying a used set - maybe from a board member who has already swapped theirs - and sending them to MBS.

We could probably get a group going to sweeten the deal for them (and us).

BTW - he said they wouldn't be able to use the mandrel bender to make these - not enough straight section between the bends. They'd have to weld - which is fine - MBS is the best around here - I trust they know how to weld.
I just bought a set of agency power dp's and sending them to a friend of mine who owns a shop and fabricated stuff for 20+ years. Full Function in the Sf bay area. They fabricated the new single turbo kit for Vishnu 335i. I wanted to gauge interest from board members once I find out the final cost.
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      07-30-2013, 09:17 AM   #15
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Quote:
Originally Posted by Rob///M5 View Post
Theoretically, I agree with the OP. What confuses and concerns me is that one owner I know had DPs manufactured from scratch and had a number of engine misfire problems. Owners of the AMS downpipes have not experienced these issues, or at least are not admitting it.

So apparently, design quality of these basic pipes does matter.
I would agree as well but the issues your friend had would be a concern. I wouldn't want to be the guinea pig. I prefer to just pa the premium for peace of mind.

I can tell you with absolute certainty that they are marked WAY up. I cannot comment but I know for sure based on a favor done for a set of downpipes for someone I know. btw..I am not speaking of AMS DP. I am speaking of a simialr high quality DP that you honestly could not get with higher quality.
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      07-30-2013, 09:25 AM   #16
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Quote:
Originally Posted by Rob///M5 View Post
Theoretically, I agree with the OP. What confuses and concerns me is that one owner I know had DPs manufactured from scratch and had a number of engine misfire problems. Owners of the AMS downpipes have not experienced these issues, or at least are not admitting it.

So apparently, design quality of these basic pipes does matter.
Do you know what code was he pulling when the misfire was happening? That is interesting, usually you experience a misfire when the cat is going bad or clogged, but not when removed. Is this guy on the board here?
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      07-30-2013, 10:24 AM   #17
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Quote:
Originally Posted by greentrbo95gst View Post
I just bought a set of agency power dp's and sending them to a friend of mine who owns a shop and fabricated stuff for 20+ years. Full Function in the Sf bay area. They fabricated the new single turbo kit for Vishnu 335i. I wanted to gauge interest from board members once I find out the final cost.
I'm definitely interested. Thoughts on incorporating the design elements discussed above - in particular the Big Daddy micro cat (for cel) and a downstream 100 cell cat from a high quality source (for fumes)?

They can use the AP set to determine the overall shape/mounting bracket/etc.

We should also look at having these heat wrapped or ceramic coated.
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      07-30-2013, 10:43 AM   #18
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Quote:
Originally Posted by dhirm5 View Post
I'm definitely interested. Thoughts on incorporating the design elements discussed above - in particular the Big Daddy micro cat (for cel) and a downstream 100 cell cat from a high quality source (for fumes)?

They can use the AP set to determine the overall shape/mounting bracket/etc.

We should also look at having these heat wrapped or ceramic coated.
Heat wrapping is very easy and you can do it yourself. Ceramic coating might be a good option.
Are stock dp's coated?
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      07-30-2013, 10:51 AM   #19
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Quote:
Originally Posted by greentrbo95gst View Post
Heat wrapping is very easy and you can do it yourself. Ceramic coating might be a good option.
Are stock dp's coated?
I don't think so - they sure don't look like it - but I believe it would be an improvement if they were.
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      07-30-2013, 10:57 AM   #20
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Originally Posted by greentrbo95gst View Post
It's like telling Coca-Cola that they have to pay 5 times more per empty can than Shasta Cola even though they can both hedge the price of aluminum and same exact cans come out.
lol - missed this on the first read. great analogy - shasta..
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      07-30-2013, 11:09 AM   #21
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Quote:
Originally Posted by dhirm5 View Post
I'm definitely interested. Thoughts on incorporating the design elements discussed above - in particular the Big Daddy micro cat (for cel) and a downstream 100 cell cat from a high quality source (for fumes)?

They can use the AP set to determine the overall shape/mounting bracket/etc.

We should also look at having these heat wrapped or ceramic coated.

Missed that too and VERY true!
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      07-30-2013, 11:35 AM   #22
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Quote:
Originally Posted by dhirm5 View Post
I don't think so - they sure don't look like it - but I believe it would be an improvement if they were.
It only works for radiation of heat in the engine bay, but I am not sure if the car would generate any more heat than stock since stock turbos are remaining intact. Usually EGT- Exhaust Gas Temp is what we should be concerned with, but the only way to control it is by tuning (amount of boost, ignition timing and fuel).
http://www.fftec.com/
Here is the shop I have been working with since mid 90's.
They recently fabricated exhaust manifolds, downpipes and built the turbo kit for the most powerful 335i in the world.
http://www.fftec.com/item/390/BMW_N5...Turbo_Kit.html

http://www.fftec.com/item/33/FFTEC_M...Turbo_Kit.html

Definitely can't argue with the quality of welds.

They attend a lot of the shifts3ctor events with the car


Quote:
Originally Posted by dhirm5 View Post
lol - missed this on the first read. great analogy - shasta..
LOL, isn't it true though?
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