I'm in!
If you can't get the group buy going. Keep me in informed. I'm VERY interested!
BTW: would a 2004 downpipe work? Since the 2004 didn't have DPF's.

 

Meeting with a VW tech who has an 04 and will compare fitment of 04-06 and 07-08. Sure hope they interchange! Already have 4 takers, so only need 6 more to make this happen. Getting excited!

 

I'm potentially interested, but need more info.... I'm not that knowledgeable on this. What portion of the exhaust would be replaced? With the catless, the Catalytic converter(s) would be deleted altogether? What about the DPF? Does that stay or go?

I'm assuming that once the exhaust is done, the ECU would have to be re-programmed, correct?

Sorry for my ignorance on the subject... I have a V10 that just hit 100k miles. What would the main benefits be?

 

The straight pipe would replace the pipes that connect the turbochargers to the catback system and eliminate the cat and DPF and any plumbing/sensor bungs. It would require an ECU tune to run properly and prevent limp mode and regenerations, and it needs to be clear that these would be for offroad use only.

 

I've got 4 confirmed and 2 more possible, still need a bit more interest in order to make this project work. Anyone?

 

I'm in

 

In. Just putting it out there, 2004's do not have dpf. We have four cats. Sensors are before the cats, IIRC. I've already deleted the muffler and enlarged the exhaust. Malone tuned, and was told a de-catted tune would be easy.

 

Edit: Just noticed the word "In." preceding your response. Thanks for the support - we're getting close!
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Artie, I am not sure I understand. Are you saying that upgraded downpipes would be easy on the 2004, or are you saying they would not be worthwhile? I'm still not sure if these are going to be 2.5", 3", 60-80mm, etc, so there still may be some benefit to be had by enlarging the pipe to the catback system. At $500, it's a cheap upgrade that could extend turbo life and net a few horsepower, but I still haven't got my hands on a 2004 model to see if the pipes would even interchange.

Also worth noting, one of my gas cars is equipped with four cats and the sensors were between the precat and the main cat. When the main cats were gutted, the sensors detected it and the ECU threw two codes, "catalyst bank [1 and 2] efficiency below threshold, MIL on, and I could no longer set readiness. Location of the sensors may be less important than resultant exhaust gas temperatures at the sensors.

 

Artie, Yoop, and N867, please send me a PM with a better way of contacting you - i.e. email, cell, etc. Thanks!

 

I'm interested in doing this along with a Malone tune but just how challenging is it to unbolt the existing pipes from the turbos with the engine in the car? I just changed my DS O2 sensor from underneath and it took 6 hours and was a bitch. I didn't look to see where the pipe to turbo bolts were but they can't be any easier to get to.

 

I've got gaskets and am going to attempt removing them here soon. When I glanced at it previously, it looked like with a chain of wobble extensions and some tiny hands, and with the transmission crossmember dropped, it would be difficult but possible.

I told the developer that if we couldn't get the old pipes out and the new pipes in with the engine in situ, he would not sell nearly as many of them, so that issue will be front and center during development.

 

I don't see the need to drop the X member, perhaps only to get a straighter shot at the bolts. With the DPF's / or cat back out of the way there will be more room to get in there for sure. I am going to do my PS O2 sensor this week so I'll have a good look then to see if I can get a socket on the bolts.

One thing that would be good on the new pipes would be to put the O2 sensors in a more accessible location. The harnesses are long enough.

 

Thanks for your willingness to help! I want to be sure you're talking about the sensors on the downpipes, as I believe there are three separate EGT sensors per side: 1) pre-turbo 2) pre-cat, 3) post-cat, and then two pressure sensors 1) pre-DPF, 2) post-DPF, and two fuel pumps.

If cats and DPFs are being eliminated, I don't see any reason to retain the post-turbo EGT sensors, but it would be really neat to repurpose the pressure sensor wiring to the exhaust manifolds for tuning purposes, assuming the temperature and pressure limits for those sensors would not be exceeded under such conditions).

By the way, thank you for your willingness to help! When I mentioned the crossmember, I was talking about the simple crossmember with 2 bolts in a line on either side of the tunnel, not the big subframe with all the suspension attached; my goal is to leave that intact if at all possible.

 

When I mentioned the crossmember, I was talking about the simple crossmember with 2 bolts in a line on either side of the tunnel, not the big subframe with all the suspension attached; my goal is to leave that intact if at all possible.

The small X member holds the center of the plastic undertray. If you aren't going to run the tray then you could discard that X member but it really doesn't get in the way at all.

The bolts on both sides will be easier after the DPF is removed and out of the way. If the new cats are even slightly smaller than the VW ones it will be a breeze installing the new pipes compared to getting the old ones off.

I am in the middle of replacing the PS O2 sensor and have found the best way to get your arm in there is above the lower suspension control arm next to steering boot covering the inner tie rod. With the steering cranked to the right and the tie rod boot dust shield removed someone with skinny arms should be able to get in there and reach all three bolts. To get my fingers on the O2 sensor I had to loosen the front sub frame bolts on that side and lower the sub frame down about an inch. If you have skinny forearms you'll be fine, if your arms are like Popeye forget it.

 

I only made my comment because the 04's might be different. The pipes might have been made and install differently for dpf vs non dpf cars. Hopefully they are interchangeable. I have been wanting to do this for a long time.

Pm sent

 

I can squeeze in just about anywhere (ha), so that's good news.

While you're at it, would you confirm that the pipes have the space to slide back off the studs that secure them? If they don't, even if all three nuts will come off, removal could still be impossible...

 

At least on the PS it will slide off no problem There is a more than an inch of room all around the cat and factory down pipe.

 

Thinking about this again you will almost certainly need to remove the O2 sensor before removing the pipe or it will hit the firewall.

 

On the PS the lower nut and the outboard one at the top can be reached through the opening where the steering rack tie rod pokes through. Turn the wheel all the way to the right to move the tie rod in and you will make a bit more room to get your arm in there. I just changed the O2 sensor which is nicely positioned between the two nuts on the top of the downpipe making it very challenging to get to. I loosened the 3 sub frame mounting bolts and let the sub frame drop down about an inch on that side to get a little more room. The inner top nut you can reach from the top. In fact both top nuts you can reach from the top. You will need to remove the intake butterfly and EGR valve from the intake to get decent access. I couldn't get my arm in the gap until I dropped the subframe slightly on that side but then was able to wiggle my forearm in down the back of the head by the tandem pump. The off road pipe swap is not going to be impossible to do but it won't be completed in a hour either. It took me about 6 hours to do my DS O2 sensor and 5 hours to do the PS O2 sensor. I would estimate that the pipe swap would be in the same ball park.

 

Just to be clear, the only sensors I'm really interested in retaining are the primary O2 on the exhaust manifolds. For those who want to run cats, cats can exist and function without monitoring, can't they?

 

There is no secondary O2 sensor on the V10 TDI at least not in North America. It is possible to get a tune that takes the O2 sensors out of the control loop and runs just off the MAF signal and the base maps in the ECU. Although I don't think that would be a good thing to do engines ran that way for decades before more sophisticated engine controls became common.. The V10 is designed to use the 5 wire (wide band) sensor and I would keep it.

 

I assume you are right on this because you were just in there looking and you have a 2007 presumably with the BWF engine. I suppose I saw a lambda sensor either pre-turbo or at the turbo on another vehicle, though I can't seem to remember where.

Well, then I'd definitely aim to keep the lambda sensors and just lose the exhaust gas pressure sensors and the fuel pumps.

Still keen on the idea of plumbing the exhaust gas pressure sensors into the exhaust manifolds and take them out of any control loops, keeping them just for informational purposes. Wouldn't it be nice to know the EMP/MAP ratio for tuning and VNT rod/stop adjustment?

 

The gas Tregs have pre and post cat O2 sensors the Diesels do not. At least not in NA.

If you install a tune that takes the DPF pressure sensors out of the control loop I don't think you will be able to access data via Vagcom for those anymore. I could be wrong. Without having the calibration curve for the sensor any data you might be able to gather using some other form of direct datalogging would be pretty much useless.

 

I've been able to monitor stuff in VCDS even though the computer didn't act on it - secondary O2s in my other car, for example. Curve should be pretty easy to obtain; its a pressure sensor with a fitting on it. Not that complicated, after all

Who knows if the EMP will exceed the range of that sensor, though, or if another sensor with that range could output a useful value? Think 4bar MAP sensors in place of 3bar...

 

Post turbo should be way less than 1 bar. Pre turbo would be interesting just run a long length of tubing to allow for the exhaust to cool off enough that it doesn't kill the sensor.

I thought the DPF sensors were a differential pressure sensor and not absolute. Do you know exactly?

 

I'm not sure on that one, but if it were the case, both sensors could be plumbed in - one to intake manifold, one to exhaust manifold. That would be pretty neat!

 

As of today:
I have 5 people (myself included) with 100% commitment.
I have 4 people with 40-70% commitment.

I need 5 more definite yes's to get this going. Is anyone interested? Nudge your friends who don't visit this forum often and ask them to check this out, because I really want to make this group buy happen. Thanks!