23 replies to this topic

[Dan A]

I'm on a stock exhaust setup right now on my 99 R. I've been thinking about fab'ing up a 3" downpipe to 2 1/2" catback for a while and now seems like a good time to do it (broke a weld on Saturday). The welder I'll be using is a wirefeed flux core type, so I won't be doing any stainless. Plus this is going to be my first attempt at anything like this so aluminized steel is fine and cheap. Function over looks is the priority, as far as the welds go too. I'm not spending $700+ on just a downpipe.

Hussein's build page shows a couple iterations of downpipes he has welded himself. I'm looking to do something like he did on his 20g. From what I can see when I'm under the car and from what he described, the plan is to come down on the right side of the bevel gear with 3" pipe. But from there it looks like I need to go under the drive shaft to run the rest of the pipe on the driver's side. Right now my drive shaft is out and probably will be for a while, so it's kind of hard to visualize, but it looks like that should be OK as the cat on the stock setup sits quite a bit lower than the drive shaft so I don't think ground clearance is an issue. I'm assuming that is what Hussein has done (maybe he can comment if he sees this).

So I guess I have a few questions.

Where is a good/cheap place to get 16ga mandrel bends and pipe?

What about a steel flange for an angled exhaust housing? I think CJ has one for about $60-$70, but is there anyone else? Or should I just cut the one I have and reuse?

What size is the hole size coming off the flange? I assume it's a little smaller than 3" and I'll need an adapter (that's what she said).

Anyway, this should be fun. Anything a novice should be aware of when tackling a project like this?

[lookforjoe]

The pipes you can buy online, get a 45 & 90 Mandrel Bend, that will get you all the bends you need, then some straight 3" pipe. Get a FLEX LINED 3" coupler, not a standard braided liner - they shrink ID as soon as you run them.

I used Performance -Curve or Mandrel Bend Solutions on Fleabay. Get two O2 bungs while you're there.
This will be the basic layout - just longer since you will be mating to the stock mid pipe.



If you want to retain the stock CAT back which is already 2.5" - then just cut the stock DP off at the CAT inlet & have them fab the 3" DP from there - like this, but not so FUGLY



Otherwise... cut the angle flange off your old DP. Run the pipe down & under the BG flange, and align it with the midsection pipe. You can eliminate the CAT as long as you get a "fooler" O2 extension - IPD sells it under their Rallitek brand, or look online. Just don't use those spark plug extenders, they aren't long enough.

[Volvo5.0]

lookforjoe, on 31 January 2012 - 12:03 AM, said:

You can eliminate the CAT as long as you get a "fooler" O2 extension - IPD sells it under their Rallitek brand, or look online. Just don't use those spark plug extenders, they aren't long enough.

I used these... http://www.amazon.co...r/dp/B000CO91FY They come 2 in a pack, and if you use both, they are long enough. Much cheaper than the Rallitek version.

[Dan A]

Thanks both. I plan to run a cat but not the stock one and i'll just assume i'll need to order a spacer for the rear O2 just in case the computer doesn't like the new cat.

Hussein - regarding the flange and hole size. will the three inch pipe mate directly to the flange or will I need a reducer to go from the pipe to the flange? (i'm wondering what size hole is on the flange.) also you wrapped yours if I recall. is that something you recommend? also what paint did you use and does it hold up? I'm worried mostly about rust on the weld seams.

thanks again. I hope this comes together finally!

[lookforjoe]

Dan A, on 31 January 2012 - 02:34 AM, said:

Thanks both. I plan to run a cat but not the stock one and i'll just assume i'll need to order a spacer for the rear O2 just in case the computer doesn't like the new cat.

Hussein - regarding the flange and hole size. will the three inch pipe mate directly to the flange or will I need a reducer to go from the pipe to the flange? (i'm wondering what size hole is on the flange.) also you wrapped yours if I recall. is that something you recommend? also what paint did you use and does it hold up? I'm worried mostly about rust on the weld seams.

thanks again. I hope this comes together finally!

I never measured the stock flange, and that was at least 3 years ago now, so I really couldn't tell you. However, I do have that "Frankenpipe" in the garage, so I can measure the ID of the flange tomorrow after work. Pretty sure it's 3", though.

[Dan A]

That would be great if you can. I'd like to know before I get it off the car so that I have the correct parts in hand.

[lookforjoe]

Sorry, I didn't get to it yesterday. I can check it tomorrow.

[lookforjoe]

ID of the flange is slightly over 3".



The OD of the pipe at the flange is approx 2.9"



The lip of the flange around the pipe is over 3.1" - you can definitely cut of the flange & weld 3" pipe to it.

[Dan A]

Nice, thanks! Practicing my welds tonight

[NJGreenBudd]

Excellent thread, I have been reading all I can about DPs for the 98 V70 and custom seems to be the best option. I have looked at H's build and DP and that's what I was hoping to use a reference. I will be following this closely to see how it goes. Good luck!

[NEU]

Custom the way to go if you have the skills or the shop to do it. I have John Sharps old custom exhaust system off his Laser. It has CJ 3" DP (it's his prototype AWD DP) it's AMAZING workmanship and quality. He also made a 3" center section with a glasspack mated to 3" dual Magnaflow that the original owner of Johns car and made. Unfortunately he didn't use stainless and it's starting to show its age... I'd say while you are at it just go 3" all the way and make a new dual system. The only reason not to is if you don't want any drone. But you could get mufflers that aren't that loud.

Also like Jeff said you can use the sparkplug non-foulers spacers. I have it on my system as I had a CEL when I swapped Johns freeflow system in, wasn't an issue in MD but needed on for VA. They are really easy to make, just drill out the center of the fouler to fit the O2. Defiantly don't buy any of the ones that are "O2 spacers", I've seen them go for ridicules prices $30-40! I think I got 2 from Advanced Auto for $5 and about an hours work. BTW here is my write up on how to make one...

[NJGreenBudd]

Would these be the correct parts:
http://www.ebay.com/...8#ht_500wt_1081

http://www.ebay.com/...9#ht_500wt_1081

http://www.ebay.com/...9#ht_500wt_1081

http://www.ebay.com/...9#ht_500wt_1081

[Dan A]

^^ I think that is about right. I think I'll order a two or three 45's because I think I'll need two. One 90 coming off the flange to a flex/short straight then a 45 to curve it down and towards the driver's side then 45 another to bend it back down the tunnel. I practiced welding last night. Definitely need to dial in the welder and do a lot more practice welds, but should be doable.

Also, going to try this:
http://www.ebay.com/...=item3cc17d58cb

And of course some bungs. I'll probably add a 3rd just in case of future wideband. I'll order parts today or tomorrow so hopefully by next weekend I'll be playing around with it. If I can't next weekend then it's probably going to be a couple more weeks before I get a chance. I have to say though, it looks pretty straightfoward if you forget that S bend and go down the right side. It will not look like CJs welds for sure.

I'm scared of 3" all the way because I do NOT want drone. It needs to be civilized when cruising.

[lookforjoe]

It's really two 90º's & 1 45º



like that, minus the WG dump piece. Mine also had a short 2.5-3" expander right off the flange, yours won't so you may need to cut the pipe at a extreme angle at the flange to bring it back down & in...

[Dan A]

Sounds good.   Where does your flex pipe go on that?  After the 2nd 90? Edit: Never mind, I assume it is the same as the 20G setup pictured at the top. Thanks.

[lookforjoe]

Dan A, on 02 February 2012 - 09:32 PM, said:

Sounds good. Where does your flex pipe go on that? After the 2nd 90? Edit: Never mind, I assume it is the same as the 20G setup pictured at the top. Thanks.

yeah - easier to have that at the end, otherwise it's difficult/impossible to fit the pipe from below - no clearance with the coupler up in the pipe as I have mine now for the LG Header install.

You can see how close the 3" pipe is in this pic



or.. just put a vband on the DP, and add the flex after in the mid pipe

[Dan A]

Do you recommend wrapping the pipe?

[lookforjoe]

I don't have a heat shield. As long as you do, I don't think it's necessary with stock turbo, etc. DON'T do it with aluminized steel - you will rot the pipe within 2 years, guaranteed.

[Dan A]

Major parts ordered

[Dan A]

lookforjoe, on 31 January 2012 - 12:03 AM, said:

Get a FLEX LINED 3" coupler, not a standard braided liner - they shrink ID as soon as you run them.

OK. First part arrived and it looks like I'm not gonna use it. I wasn't sure what was meant by "flex lined". I thought you meant getting one that had the bellows rather only braids. So I got one that was double braided with the bellows in the middle. But I got it today and the thing loses almost about 3/4 inch in I.D. Take a look. Kind of hard to tell in the picture maybe. Is this what I can expect?

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