Homemade twin scroll options/opinions

[vrmm]

So I have both flanges now and need to choose piping. I can get 10ft of straight 14 gauge piping for 16$. Not 100% sure how I will bend it, but I'll figure that out when the time comes.

Both flanges are mild steel so I'm sticking with that. I can probably get sch 40 .125" piping in mild steel but it would be expensive. That's fine n' all, but I'm hoping to get away with the 14 gauge since oriellys has it. My hx35 weighs 30lbs so I suppose that's my question. Will it work? Dsm people do it all the time, but as far as longevity goes I don't know.


Guhhh updated again with actualy pictures not blurry photobucket shit. And here a pic (only one I have off my front bumper mostly cut out for my fmic like mikes/even though i've read it doesn't do much for iat's..)

11/something/2019

[redline380]

I'm not a metallurgist, but it sounds like you are going to want higher quality shit than oreilly stuff.

[vrmm]

It's decent piping. I've used it before on my old Subaru for an uppipe. It worked good, but the td04 only weighed 15lbs or so.

I guess I'll just have to try it. It was a stupid question to ask :) I'll probably hit up a few steel wholesalers on the way and be done with it.

[vrmm]

So I got 15ft of sch 40 pipe for 10$. The only place in town I've found that can mandrel bend wants 120$ which is not too bad. I feel like the size of the pipe is way over kill, so I'm looking at 180 degree pre bent mandrel 16ga mild steel again. Mandrel-bends.com has them for 10$. I can get 7 shipped for 75$. It sure would make like a lot easier to just do that.

[vrmm]

I bought 7 of these.. 110$ shipped. My flanges are from ebay. 1 & 1/2" mild steel. The twin scroll is pre tapped and comes with studs and bronze bolts. I'll probably use my current locking nuts though.

http://www.mandrel-bends.com/catalog...bend-2022.html

In a week or so I'll update this with how many 90's it actually takes and all that jazz. Maybe make some sort of diy. I can't imagine it would be that simple and easy to replicate though.

[Avant Nate]

What are you using for the collector and head flange? Ever since I saw Zimbus, (http://www.audizine.com/forum/showth...ild-%28pics%29) I've looked into doing a few times, but never pulled the trigger.

[vrmm]

I'm just gonna take straight pieces, press them into the correct oval shape, and cut them at the same angle to fill the flange ports. I have been thinking that will be the easiest part. Hopefully I'm not wrong! I updated my last post on the two flanges i'm using. For the header i'm using an ebay 1.25" port (not sure where that comes from), 1/2 thick mild steel. The ports are conical. They start at 1.476" on the head side and on the turbo side 1.602".



The sch 40 3.7mm piping I bought

[vrmm]

If it matters to anyone that sch pipe I got was astm a53.

[melomandn]

What's your plan for the wastegates?

[vrmm]

Cutting a 2-2.5" straight in half and placing a flat piece inside then welding it back together with an additional section protruding to fill the recessed wastegate space. It will be my last step, so I'm currently winging the length. I already have a flange from my crappy 034 stainless downpipe that wouldn't allow my wg to flow back in.

[vrmm]

I'm doing a single 38mm. From the info I've gathered I won't have any issue. If you disagree feel free to do so!

[Avant Nate]

I'm doing a single 38mm. From the info I've gathered I won't have any issue. If you disagree feel free to do so!

I thought you had to have a separate wastegate for each scroll, otherwise they wouldn't be separate.

[vrmm]

It will be something like this..



a4rob had it that way too I believe.

[vrmm]

So I got my piping extremely fast, but i'm going to alaska for a week, so this'll be on hold.
It definitely looks like it is up for the job. I'm already pretty sure i'm going to need a couple more straight pieces. I thought the straights were going to be longer on each side.

[Avant Nate]

Band saw or chop?

[vrmm]

I have both but will being using the chop more than likely.

[M-Hood]

It will be something like this..



a4rob had it that way too I believe.

Rob has 2 wg's, there was a B6 owner that made his with a single but he sold the car for a b5 S4.


JDL Auto Design offers a true twin scroll T4 with dual WG flanges for under $1000, friend of mine is running it on his B5 A4.

[melomandn]

Mike, I'm sure you'll know the answer to this.

I was under the impression that the only proper way to run a twin scroll was with two designated wastegates. Besides the obvious fact of taking up less space, what are the pro's and cons to a single wastegate?

[UroTuning]

Rob has 2 wg's, there was a B6 owner that made his with a single but he sold the car for a b5 S4.


JDL Auto Design offers a true twin scroll T4 with dual WG flanges for under $1000, friend of mine is running it on his B5 A4.

Thats a nice setup!

[M-Hood]

Mike, I'm sure you'll know the answer to this.

I was under the impression that the only proper way to run a twin scroll was with two designated wastegates. Besides the obvious fact of taking up less space, what are the pro's and cons to a single wastegate?

With a single WG, once the WG opens the exhaust pulse on either side can pass thru the WG and back into the other side of the manifold, basically mixing the 2 again. This is why a true twin scroll is always going to have 1 WG for either side of the manifold. As you can see with the JDL T4 twin scroll manifold it is possible to do dual WG's, it will just be harder to try and run the WG dumps back into the down pipe if that is what your looking to do.

[vrmm]

Does it realllly mix them with all that pressure? Why would cyl 1&4 gases leave their runners and choose to crawl into 2&3?

When you say true twin scroll does that mean a single wastegate twin scroll is essentially useless and only beneficial because of the smaller size of runners? I've read a lot of forum posts and no one has really knocked single wastegates..?

[MetalMan]

For single WG in twin-scroll configuration, I think it could make a difference whether you route the dump tube back to the exhaust or dump to atmosphere. If routing to exhaust, then here's my take:
1) cylinder 1 or 4 fires, cyls 2/3 have no pressure. There's pressure in the exhaust because well, there are still exhaust gases (albeit not high pressure).
2) wastegate opens. Since there's no (or relatively little) exhaust pressure in cyl 2/3 side of WG port, and potentially higher pressure in exhaust (compared to cyl 2/3), then the pressure from cyl 1/4 combustion may find the path of least resistance to be cyl 2/3 WG port.
3) Now cyl 2/3 WG port has higher pressure than it otherwise would with dual WG, which means there is less pressure difference on either side of the scroll. (as you know, greater pressure difference on either side of scroll = higher turbine speed/power).

In conclusion if you route WG dump back to exhaust, the faster-spool benefit of twin scroll may be somewhat diminished.
On the flip side, if dumping WG to atmosphere, there is no exhaust pressure so cyl 1/4 won't "leak" to cyl 2/3.

Does that make sense? Take it with a grain of salt, for I am surely no expert.

[Avant Nate]

Does the Holset turbine look more like the flange you purchased or like this one with more squared off holes?
http://www.punishment-racing.com/vib...ge-mild-steel/

[M-Hood]

Does it realllly mix them with all that pressure? Why would cyl 1&4 gases leave their runners and choose to crawl into 2&3?

When you say true twin scroll does that mean a single wastegate twin scroll is essentially useless and only beneficial because of the smaller size of runners? I've read a lot of forum posts and no one has really knocked single wastegates..?

not useless, but just not as efficient. Only reason to do a single WG on a twin scroll manifold is if you were on a very tight budget or trying to run the exhaust back into the down pipe. Geoff of Full-Race explained it to me years ago when I asked about doing a twin scroll external WG manifold on my car and he should me one of their manifolds for another motor setup that used a single WG because there wasn't enough room for 2.

[Avant Nate]

Here's a cast one, too bad the waste gate is facing the wrong way. http://m.ebay.com/itm/171898606662?_mwBanner=1

[vrmm]

The issue with the tma06 I came up with was that the turbo flange sits even with the runners so there's pretty much no chance my turbo will fit. I think my hx35 touches or comes extremely close to touching the hood matting stuff as it is with the tma04. Tma04 that everyone uses has a 44mm drop on the highest side and 89 on the lowest. Technically with how high it is on the tma06 it won't matter that the wastegate faces that way. As long as you're just dumping it...

I talked with them foreverrr about all the 1.8t manifolds and all the transverse won't fit for various reasons(they didn't know, but I figured it out via their blueprints). He said he'd look into coming up with a twin scroll top mount longitudinal version... But I don't think that'll happen.

[Avant Nate]

I was more showing as an example of a divided single wastegate, but thanks for the additional info. I started thinking about it. The wastegate would be either facing down or up, and would be easy enough to route it back to the downpipe.

[vrmm]

Ohh gotcha :) that's exactly what I'll have. I am in Mikes first category ;) I've already spend over 12k on my car not including its original purchase, so my bt'ness is not going to be receiving a majority of my extra $$$ anymore. I hope my 125$ Hx35 and this custom manifold pans out. My engine is stock minus rods at the moment, so I suppose that says something. I even reused my rod bearings with 126k since they're within the limits. And after pulling the head 8ish times I've only changed the bolts once.. The first time. Never again. Wasto mone'kneeee.

[vrmm]

So day numero uno. I'll probably be done tomorrow, but maybe not.. I am thinking putting the wastegate pipe on is gonna suck.
I got really good penetration, but since I was welding outside while the wind was blowing really hard the welds vary quite a bit.
It's built around my 034 downpipe. I figured it would be easier to not have to crawl around under there. Plus most other options would've placed the intake straight into my headlight and that more than likely would've been a bigger headache.
It will be the same height as my spa top mount just 3/4" closer to the passenger wheel well.


The collector (minus wastegate) was as easy as I thought. I cut at .922"s and at an 18 degree angle.
Then heated em up to 600ish degrees via a heat gun and smacked them on each side with a sledge hammer :) Worked pretty good.




hour 3 or so. No rush. I found it easier to get one runner done then live with the rest and I don't think I could've planned it better

[Davdraco1]

Looks good man. Can't wait to see the final install.

[M-Hood]

Talked to JDL about the single WG setup on a twin scroll manifold, they told me as long as the WG isn't right up against the collector and does have a divider in the WG tubes from the collector there really isn't all that much difference in efficiency then using dual wg's. I know of another A4 1.8t owner that is thinking of going twin scroll and wants to run a single 44mm WG to make things simpler to dump it back into the down pipe.

[vrmm]

Still no wastegate :p It's definitely unequal in 2&3 by a 3 inches or so. I chose to leave a bunch of room so I won't have any more issues with blowing out turbo outlet couplers and oil drain hoses.
It has been an issue ever since I've bt'ed.
My spa manifold had a massive crack above all the runners, so hopefully, regardless of being unequal, it'll be an improvement.
I'm in the process of cleaning it up a bit so it kind looks like crap :) Is header paint going to burn off? hx35's are only oil cooled, so not sure if that affects the temps at which it will burn off.

Cough fuck Photobucket

[vrmm]

Mike that's awesome to hear! Makes me far motivated to finish :) Thanks for the info.

[vrmm]

The angled piping I bought was fairly wide(although good nonetheless). I'm not sure if it could be any tighter, but it was quite the task to get the tight angles on 2&3 or maybe I just do'nt know how to work it well enough...

[UroTuning]

Keep the updates coming!!

[vrmm]

I'm donezo. I am going to have to change my downpipe a tiny bit. Right now my v bands don't line up.
I haven't driven anywhere. I'm too exhausted :) I'll update with how that goes.






Q

[melomandn]

I'm too exhausted :)

Damnit.... hahaha

[vrmm]

Haha

Soooo my downpipe leak is really annoying, but otherwise I really like the improvement. Load depending it has full spool from 4400(3rd & up) to 4800 I'll have to drive it more to know for sure. 1st gear is actually usable now which is quite nice! I had almost no power until 5k before in every worst being 1st. Now it starts moving around 4k and is audibly louder before that(whistle wise). That's better than my comp 5456 on the spa top mount.

I don't like my exhaust tone. I used to love it. Now it's just a 4 cylinder with 3" exhaust. Before it was extremely bubbly and gargly. Now it's just flat.

All said and done I spent 177$. If anyone out there chooses to buy from the place I did, 7 was enough. I only had one 90 left over though and a bunch of straights, so if you're going off of a full race you should probably get 8 or more. It took me 3 days with a total of 18 hours or so

[vrmm]

SoooOOoooo I don't know if any one else has had the issue, but after driving swiftly multiple times the studs and copper nuts that came with my flange have decided to evacuate. I believe it's because the holes go all the way through. I was expecting the worst after having no boost, but thankfully! it was just loosing 2 studs and one nut. I plan to weld the bottom portion of the hole closed where the stud screws in and also tap the flange for my other studs with self locking nuts(cheapest option).

I have discovered the reason why some twin scrolls point towards the headlight as much as they do. My downpipe is still vibrating on the firewall/strut area even after adjusting it. I'm going to have to do a 45 degree immediately after my exhaust to turbo v band.



Watch the fail happen :p No boost after shifting and not much before..

[Avant Nate]

Did you gasket match the flange to the head? Because 1.25 is a little small. I measured mine at 1.4something, pretty much the same diameter as the ID of the pipe you bought.

One other thing I noticed, is no one makes a t3 twin scroll for our platform, it's all t4, for the efr's.

One more ?, why did you angle the waste gate down, instead of back?