Downpipe post install thoughts, concerns, regrets, questions

[makjur]

Cobb downpipe install took me around 10 hours. Not a fun experience, ran into some typical problems and have a few leftover questions/issues.
This was done on a 2010 speed that had 38000 new england miles on it.

I read the shit out of every thread I could find before I even planned the install, and pretty much regretted buying the downpipe before it was even installed...
Kept reading about all the things to worry about and that could go wrong.

1. Ruin one or both o2 sensors by crossthreading, or using too much penetrating oil
2. Heat shield bolts strip threads or heads
3. Remove or torque down 5 bolts from downpipe to turbo flange
4. Break a bolt to turbo flange and have to remove turbo to extract the bolt

Thankfully I only ran into 2 of these issues myself.
The heat shield on the original downpipe has a screw facing the firewall. It took me well over an hour for this one fucking screw. Pneumatic chisel, stripped head extractor, and vice grips got the job done - fuck this screw.

Got to all of the bolts on the original downpipe no problem from the top, was so excited things were going smooth again.
Started removing the downpipe and almost called it quits... install guide from cobb and corksport says "You may have to twist and maneuver the downpipe to get it past everything". This is a huge understatement.
Its like trying to shit out a pumpkin with spikes on it.
The factory downpipe has tons of heat shielding, a bracket welded on for 2 extra bolts, and wire hangers for the O2 sensor cable.
This is where I wanted to call it quits, shove the thing back up, bolt it back on and turn my new downpipe into a bong.
After mangling some of the foam/foil heat padding attached to the exhaust channel on the body, I got the old downpipe out.

Putting the new downpipe in was a little easier since it didnt have a giant heat shield and little fucking wires sticking out of it. The length of the cobb dowpipe made it a little harder. If I were to do this again I would go with a 2 piece pipe, or even the full race design that has a separate bell mouth all together.

Bolting the new downpipe to the turbo flange was the next moment that made me regret spending so much money to be in this position.
The top 3 bolts were easy, sockets fit on all of them, was able to get them on no problem and snug them up. The 2 lower bolts dont allow for socket to fit because of the bell mouth on the Cobb downpipe. I had to use open box crescent wrenches and turn them little by little since the ratcheting wrenches I have were too fat to fit.

The downpipe is in now, I still havnt found a good way to keep the wire from the O2 sensor out of harms way. The zip tie I decided to use for now is tearing at the heat shield that sits behind the turbo, so this is the first thing I want to fix. I put a red arrow in the pic where its rubbing.
Whats the best way to have the primary O2 sensor cable routed to keep it from getting harmed?

Question 2 is, should I stop worrying about the under-belly heat shield I tore up removing the old downpipe? I'm worried it will get wet, retain water and dirt, start rotting and spread.

Last concern is the donut seal that mates with the catback, there is a gap between the flanges but it seems to be sealed properly. Does the cobb downpipe have too long of a dick for the donut gasket to sit on? I'm woried that its hitting the OEM catback and not allowing the flanges to meet.

[mrtheandrew]

i did mine during my lunch break. how did you lose your arm?



just messin', ive heard it can be a bitch and am somewhat dreading it myself and even considered just doing a race pipe. the downpipe i have sitting in my garage mean mugs me every time i pass by. what are your initial impressions as far as sound/power?

[brandonnicholson]

Should have had some people over to help, we got someones done at scotts a few weeks ago in like 4 hours while doing suspension too. For the donut gasket i bought one at auto zone for a 96 cadillac deville or some shit, 3 inch gasket fit perfect,

[rolanblack]

Man. Should have made a little slit in the head shield to run the sensor through. Just my .02 cents

[rodrigo]

First time always sucks .... First one we did 8 hrs .... By the 20th 3hrs flat no power tools lol


O2 wire looks fine , fuck the heat shield on the bottom ...and as long as downpipe seals who cares .... Enjoy

[AshFromCan]

Thanks for the anecdote. You got it done and that's the main thing.
I'm planning on doing mine eventually and am prepared to devote a whole weekend to it if I need to.

[havocforming]

I feel your pain man.. when i installed my cp-e downpipe i almost gave up as well. Pulling that stock downpipe is ridiculous, i remember mine seemed like i had gotten it stuck, wouldnt budge in any direction, so while laying under it looking up i kind of raged and smacked it a few times and then it just fell out. I was totally blown away. then i forgot to torque down the lower bolt on the bellmouth thats closest to the manifold. got everything put back together and started the car, only to have exhaust pouring out of my hood scoop. that was my stupid moment.

Happy with the outcome, never want to do it again lol

[Hargarbl]

Mine ended up taking about a week to do. But I had a stud and nut seize up on the turbo to dp and had to pull the turbo to get it drilled out, when the turbo was out I noticed I had quite a bit of shaft play so I had it rebuilt while it was out. Yours wasn't that bad in my opinion lol.

[Koke382]

Myne took for ever, heat shield was welded...lol jk but it fucken felt like it. Took up most of a nator instal day and half of the guys to do it.

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[calizoomzoom]

Access to a lift would have helped. I did mine in 4 hours by myself (long dp) on a lift. Wasn't a fun install tho

[makjur]

I added year/milage to my OP for future reference

Originally Posted by mrtheandrew what are your initial impressions as far as sound/power?

Going from a test pipe to this isnt much louder, but there is a definite change. As for power I can tell the turbo spools faster, still waiting on a new map so I'm afraid to put the hammer down since it spiked to 20.5 psi without an issue at low rpm.

[makjur]

Originally Posted by rodrigo O2 wire looks fine , fuck the heat shield on the bottom ...and as long as downpipe seals who cares .... Enjoy

I'm more concerned the zip tie I'm using will scrape away the insulation shit and make a mess at this point, the wire seems out of the way. I guess I'll add more zip ties to keep the one holding the wire from being so close to the shield

[Helrich]

I might just be a retard but for me getting the stocker out through the bottom took about 5 seconds, and getting the new one up the chute and onto the studs took 20 minutes. And then I realized I couldn't get a good angle on the lower O2 sensor so I had to take it part-way back out to do that, almost got my arm stuck trying to plug the fucker back in with the DP in the way.

[neganox]

Nice job manning up and doing the job yourself OP. It also took me many hours to do my installation. I was hung up on that stupid 5th nut on the downpipe flange. I wouldn't worry about the o2 sensor wires as I believe the sheath that covers them is high temp and wont melt. If it really bugs you, you can run another sheath over it from DEI or similar.

[predapio]

I remember that little screw in the back of the stocker.. it sucked.

Rolling the stocker out wasn't too bad.

The worst is tightening up the last bolt on the flange. turn 1/8th turn, spin, turn 1/8th turn, repeat.

[Danfriscia3]

A buddy and I did mine one afternoon. Car only had like 10k miles on it so bolts came off easy etc. it was both our first attempt and it only took us 3.5 hours. However getting the stock dp out is a bitch. I did the same thing scraped up all the insulation coming out haha. That took the longest, getting it out. Then getting that secondary o2 in was just annoying because of the awkward position it's in. I did the same thing with the first o2 with the zip tie. I advise you to use another one because it moves and the o2 then Gains slack.

[usgiorgi]

@DarkFire989 and I did his DP and catback in ~5 hrs. The bolts on the bottom are by far the worst. Turning them little by little via a crescent while your forearms are already tired is awful.

Don't worry about the gap between flanges. It has to move around. The donut is there to keep things sealed. There'd be a problem if there was no gap

And for the heatshield, if you're so worried about it, get some reflective tape and tape over the edges.

[makjur]

Took a clothes hanger and made a small coil on one end that I fed the o2 cable through. Zip tied it to the AC line, it goes down a good foot and keeps the o2 wire well out of harms way. Will keep tabs on it after every drive to make sure its staying in place.

[blakkat]

Or you could do what I did and take the two nuts off the heat shield and put the wire behind it.....


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[kritz]

Best solution^

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[makjur]

Originally Posted by blakkat Or you could do what I did and take the two nuts off the heat shield and put the wire behind it..... Sent from my iPhone using Tapatalk

The one that is against the firewall (in my picture it would be to the left)? I didn't even look to see how easy it is to remove that. Thanks

[blakkat]

Yeah that's what I did. There only 2 nuts holding it on


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[makjur]

Started retuning with Mr @Justin@Freektune; and right away AFR's arent in order.
Latest WOT pull starts off with readings between 11.7 and 11.9. After 5000rpm I see 11.4, 11.08, 11.7, 11.9, 10.9 ...

Checked for exhaust leaks around downpipe/turbo flange - I'm assuming it would be a sooty mess around the flange even if it was a small leak ... not seeing any signs

Going to order a set of JBR boost tubes, just to have t-bolt clamps, and some more tube meat around the fittings. Might pick up a turbosmart kompact bpv while I'm at it.
Will remove, inspect, and reinstall my cobb sri/tip, and run new tubing to my grimmspeed ebcs while I'm at it.

Hoping I didnt fuck the primary o2 sensor, I didnt use much PB blaster when I was removing it - would there be other signs indicating that the sensor was fucked?

[Anaphra]

Not to be reviving a dead thread, but how much is too much PB?

[MSMS3]

Originally Posted by Anaphra Not to be reviving a dead thread, but how much is too much PB?

You really can’t use too much. Spray until it drips off of each bolt or the sensor body. The key is to let it soak, come back several hours later, if time allows, and spray again. It needs time to work its way into the threads. Kroil works well to. Then, go very slow.

I know this was a dead thread, but your question is relevant and the thread is worthwhile, at least from my perspective.

[Anaphra]

Ok so follow up question, I've got an east coast car in CA, and I've already managed to snap a few bolt heads. Are the any precautions I can undergo leading up to the install to prepare the turbo studs and bolts so that I don't snap them off and have to pull the turbo to drill them out.

I've talked with a few of my mechanically inclined friends and they said just spray them down the week of doing the install so that they get not only heat treated but also chemically treated. Would this be the smartest approach? Or am I risking damaging something else?

[Vansquish]

Originally Posted by Anaphra Ok so follow up question, I've got an east coast car in CA, and I've already managed to snap a few bolt heads. Are the any precautions I can undergo leading up to the install to prepare the turbo studs and bolts so that I don't snap them off and have to pull the turbo to drill them out. I've talked with a few of my mechanically inclined friends and they said just spray them down the week of doing the install so that they get not only heat treated but also chemically treated. Would this be the smartest approach? Or am I risking damaging something else?

Nope, that sounds like exactly what you need to do to loosen the bolts, nuts, and studs that you need to loosen. They need a chemical penetrating lubricant, and heat cycling to break free. I did this exact procedure on my car when I swapped turbos at around 100k miles, and everything came apart super easily.