Sometime last year, I started to hear voices in my head. "The 16G turbo is ancient technology" they said. Then it was "you are leaving power on the table with your old log manifold". It continued, "internal wastegates are for pussies", "grow some ball bearings", and so on. I couldn't take it anymore, so I decided to build a tuned, tubular, equal length, 4 into 2 runner manifold with a twin-entry Garrett GT3071 turbo and divided, external wastegate.

The only problems are I have never designed a manifold, I don't have any 3D CAD software, and I don't know how to weld. I scoured the net and text books for month and came up with enough formulas to determine runner sizes and lengths (1.682" ID primaries, 2.210" ID secondaries, and 28.9" from head to turbo). Then, I borrowed SolidWorks '05 software and learned how to use it. I created each component and positioned them to match the available space and my earlier calculations. Lastly, I watched a sanitary welder at my work for about 20 minutes and started practicing what I saw on the company TIG machine.

Now for the disclaimer:
I still don't know much about designing manifolds
I am still a C average CAD designer
I am still a C- TIG welder
Follow my example and your car will burst into flames, killing you in the process!

Let the journey begin:



I lived and breathed SolidWorks from December to February.




I designed the head flange using a spare 2GNT head I just happened to have lying around. I designed the turbo and wastegate flanges from the Christmas presents I bought myself. The flow length of the runners is equal to within 2 mm “in theory”.




I obtained a plate of 304L SS and had a shop CNC the flanges out. By the way, I had a few extra cut, so watch the For Sale forum.




After about a month of dick dancing, burning flesh, and an angry wife, I have everything tacked together for test fitting. Everything is 304L SS, 0.109” wall pipe. Note the numbers to indicate location and lines to indicate orientation.




I didn’t take pictures of it, mostly to block the horror from my mind, but I made steel dies to form every transition. With a torch and die, I was able to form the “head to primary” transition, “secondary to turbo” transition, and the collectors. Without a doubt, the eccentric taper and “D” shaped turbo inlet of the “secondary to turbo” transition was the worst. Scratch that. Making the second one mirror the first was the worst part.




These were some of my first welds. My skills were comparable to Ray Charles on Ephedra. I did back-purge with argon and inspect the interior for full penetration. I overheated the weld, didn’t clean the joint well enough, sucked at welding, etc.




The #2 & 3 collector weld shows some improvement.




That #1 & 4 collector can kiss my ass. Most of those welds are ugly. You can see the divided external wastegate mocked up though. That one came to me in a dream one night.




Now I start to realize that my welding head won’t fit in half of those crevices.




Things are starting to come together.




Yay! It’s done and I wrap the ugly welds with header wrap. Good thing, because every pipe is about a quarter inch from something important (radiator, starter, hood, coolant pipes, A/C lines, to name a few).




That little tube is the wastegate dump into the downpipe.




Ball joint braces to support along two axis and allow movement along the third.




I also made a 3” OD, 0.065” wall 304 SS downpipe with V-band inlet. The outlet tapers to a 2.5” flange for my cat (temporary).




Oh, there’s a radiator there! Better weld a flat panel into that elbow in a very critical place for flow. You’ll hardly know that 25 hp is gone.




This guy gets wrapped too. Just in time too, as I had almost healed from wrapping the manifold.




Oh, none of your intake pipes fit now. Better weld up a complete set from scratch. This time it is 2.5” OD, 0.065” wall 304 SS tubing. Did I mention the angry wife?




Downpipe scratched a hole in two perfectly good stock radiators? No matter, just buy a VW Scirocco “racing” radiator to fit where the A/C condenser was.




3 weeks later, we have this. Everything has a heat shield, because everything hot is a quarter inch away from everything that is not supposed to be hot.




So, if you move the radiator to where the condenser was, where does the condenser go? The logical answer is “right where the hood latch and center support used to be”. But the stock condenser won’t fit there. So, you get a custom A/C condenser and lines. And the aftermarket fans go between the F’ing headlights, touching the power steering cooler, which is touching the intercooler, which makes me cut my bumper even more. Good times.


Corbin

'95 ESI-T
Now with more power and fewer leaks



Gimme fuel...Gimme fire...Gimme that which I desire

I <3 you in a completely non-gay way.


Before i lost shop access (regained recently when i found a new shop to "loiter" in), i had been welding tig for four years. It's like driving a 5 speed. All feel. Dont beat yourself up too bad. Your welds look decent. I've seen far worse. Nice manifold. I'm sure it took 3 or 4 shitloads of work and it shows.

I read every bit of that and looked at all your pics.I dont even know what to say except good job and congratulations.I want to see some dyno sheets!

Nice work, something I could never have the time/patience to bother learning to do. I especially like the story that went with it and the parts about the wife being mad :D

Looks great, turned out great, I love it !!! After all the time and effort, dont you just feel relieved that it turned out great.

EDIT: This is awesome. We are finally starting to get 2gnt's to hopefully making good power with custom work. Between your manifold, my manifold, quicksilver;s manifold, and that other guy (sorry I forget who it was, lol) making all these different designed manifolds, 2gnt's hopefully will get some more props and respect for what we are trying to accomplish, especially the guy who is building that 420a 'race' car.

Amen to 2gnt's :)

Wow Corbin, you did a damn good job for just teaching yourself I'd say. Very impressed. I'm sure the wife is happy too haha :)

Have you ran the car yet since everything has been installed? Just curious to see how she runs.

I am at a lose of words....you are amazing man! Great job Corbin...very impressive. You inspire a lot of people on here...just in case you didn't know that. :bowdown

Corbin- as mentioned, very impressive work especially for the fact that it was self taught within the limited timeframe mentioned. You continue to be creative, that is great to see.
That thing will prove to work very nicely as you know, but for reference, Jon Shepard had a very similar design last year (only opposite flow pattern due to being on his 4g63) which was made by Shearer Fabrications. They have since released designs very similar on a production base for the 4g's- just not our cars yet.
Keep us updated on the progress, it's great to see someone else stepping back up to the plate!



--------------------------------------
Santiago
boosted 420a...(2.2l v8 eater)
02 WRX
95 T/A 383ci
03 Harley XL 92ci w/ NOS

Corbin,

I hate you.

That is all.

*thinks about the mig welder in the garage*

I wish I knew how to weld.

Wow that looks amazing, awesome work!

Congrats...damn engineer ( im an Industrial tech ;) )

Love solidworks, great program, did you use any of the simulations?

wow..... . . so hot... . .



Its ime to throw out my S20G and plan for shootout '08.

Originally posted by Chamuko
Congrats...damn engineer ( im an Industrial tech ;) ) Love solidworks, great program, did you use any of the simulations?

Yeah, FLOWORKS would've been a real nice thing to have for this... I'm sure it flows better than anything else, nevertheless.

-http://www.symtechlabs.com/-

So when does production start and how much? :)

wow wow wow wowwwy /christopher walken

That divided external wastegate came to you in a dream? Ah, to be a genious, LOL. Very inspiring - I love to see things followed through to the very end. Awesome work! If you don't come back with a dyno soon, I hate you too

Can I ask a question about the thinking behind the external wastegate? You obviously kept flow in mind from flange-to-flange. When making a small outlet to the external wastegate, does having it on the outside of the radius potentially cause turbulance in a vital section? I'm designing a manifold (my autocad skills suck), and I've thought about keeping the outlet to the wastegate on the inner parts of radii or at least perpendicular to straight sections of the manifold. When I see your work I know that you've considered everything, so I have to ask the master.

I want the voices in my head to be like yours Corbin. Mine just tell me to do bad, bad things :twitch

so is this gonna be the new "Corbin Spacer" group buy model?
lol

all serriousness, nice work man!! really intrested to hear how it runs / sounds / and of corse the gains!

every time my wife gets pissed about my car, for some reason it usually ends up costing me a really shinny lump-o-carbon attached to a gold band

Great work Corbin....as usual.

One question for you. Why did you make the head flange so light? You must have had it bolted to the spare head when welding...otherwise it would have warped like a banana. On the same note though if there is a little warpage it will more likely to "un-warp" when you bolt it back up.

I'm tempted to ask you for you SolidWorks file. SolidWOrks is how I make my money :)

you are the man and I want one if you make any for the public. oh and I can offer you my guest room I live on a golf course in hawaii just think no more angry wife. your mani got her to hawaii.

Thanks for the kind words guys. My goal was to try something different and see what the benefits and losses are. It has some compromises, but I am still happy. I am pretty convinced that I gained torque off boost. The spool up characteristics are very different though. It is a more linear spool up versus the 16G/log setup.

The goal of the head flange was to isolate each runner to minimize the possibility of warping and buckling the flange or shearing studs. A side effect is that each runner is thermally isolated during the welding process. It might as well be four separate head flanges (one for each runner). You have to carefully watch your heat input or you will warp the part of the flange you are welding. I bolted the flange to a spare head to keep the bolt holes lined up and act as a heat sink. Someone who can weld better than me would probably have no difficulty.

I never ran any simulations on it. Neither static loading nor flow simulations. Mainly because they would not change my design and only serve to depress me. There are very few ways to fit all of those components within the confines of a mostly stock engine bay. Like a huge labyrinth with a hundred rings, but only three unique solutions.

My goal with the wastegate piping was to strip off a percentage of the total flow from each secondary in a fairly smooth manner while ensuring that the wastegate was not completely ignored. I picture it like a "Y" fitting with one arm considerably smaller than the other. The actual opening in each secondary is actually much smaller than the wastegate piping. The individual openings each equal one half of the total area of the wastegate inlet opening. The concept was to dissipate the energy of any exhaust pulse that might be reflected off of a closed wastegate valve. The length and diameter of the wastegate piping was mostly to reduce the interaction between the secondaries. Most of it boils down to whatever made sense to me at the time, without attention paid to any particular laws or formulas. This is a world where you can get overwhelmed by calculations and I didn't want to fall victim to "paralysis by analysis."

Corbin

'95 ESI-T
Now with more power and fewer leaks



Gimme fuel...Gimme fire...Gimme that which I desire

you need to get new carpet!

Damnit Man now I got to get one of these cars together so I can come up to the bat cave and see this thing. For those of you who don't know I helped Corbin with this manifold. When I would see it I would say oooh pretty and ask stupid inane questions about the flow principals he was working with.

Corbin is back!

I didn't take time to read all of the replies, but it looks like you re-located your fans to the inside of the radiator? Or am I seeing it wrong? What did it take to do that? I may need to so something similar for my setup...

I originally put two 12" E-bay fans on the outside of the radiator. They were just zip-tied in place and wired into the stock harness. From what I can tell, fans like this do a poor job pushing through a radiator (even with shrouds sealing the edges). You get noticeably more airflow when the fan is set up to pull through the radiator. I am now trying to find room for puller fans.

Originally posted by .bs0d
I didn't take time to read all of the replies, but it looks like you re-located your fans to the inside of the radiator? Or am I seeing it wrong? What did it take to do that? I may need to so something similar for my setup...

Corbin

'95 ESI-T
Now with more power and fewer leaks



Gimme fuel...Gimme fire...Gimme that which I desire

I think the biggest thing with fans is the CFM rating, granted surface area covered matters too. I have 2 12" slim line cyclone pusher fans from FAL, the ones with the S-blades, and the car idled at 201 degrees according to MS. 207 when I was on it. I'm curious to see what the difference is when its back together with the 160 degree T-stat.

Where did you buy the SS tubing from? I tried google searching and every site i found was for very large qauntities. I am finally good enough at welding, I think, to try building a manifold and if i can find a place to get a decent price on the pipe it may keep my "angry wife" from becoming totally enraged.

got mine from www.acestainless.com

I got my intake/downpipe tubing from Ace Stainless as well. That guy has very good prices and ships quickly. The elbows and pipe for the manifold came from McMaster Carr (before I knew about Ace). If you can't find it elsewhere, they have a lot of parts at OK prices and ship very quickly.

Corbin

'95 ESI-T
Now with more power and fewer leaks



Gimme fuel...Gimme fire...Gimme that which I desire

I get mine two places. One is from My full time job and the other is from my part timer at the shop me and my friends started. Either way it usually comes from a company called Ryerson, which place I order through depends on where the trucks are goin at the time. Elbow's come from mcmaster-carr. And the flanges are home made out of flat bar-stock from a variety of places. I work in the welding industry so I just watch for who ever has the lowest price at the time. Thin wall pipe and elbows/fittings can be had from VNE. They're only half an hour away from me in Janesville wisconsin so I just usally place large orders at a cut rate and pick them up. Otherwise look in the Phone book and find a welding/cutom fab shop in your area. They usually have drop's layin around that they might just give to you. If not they can usually get something from they're vendor for a lot cheaper than you could because they usually have bulk rates and discount price.

dang dude corbin does it again. he never ceases to amaze me! Pushing the 2GNT-T to its limits

Okay, my pipes are on the way to build one but now i have another question. How did you guys transition from oval head flange to the round tubing. Did you just kinda bend a round pipe to be more oval or what?

Originally posted by Crab1092
Okay, my pipes are on the way to build one but now i have another question. How did you guys transition from oval head flange to the round tubing. Did you just kinda bend a round pipe to be more oval or what?

yes

you can crush it in a vice, or smash it down with a hammer. Let the mood your in decide how you do it :bash

Originally posted by Crab1092
Okay, my pipes are on the way to build one but now i have another question. How did you guys transition from oval head flange to the round tubing. Did you just kinda bend a round pipe to be more oval or what?

I made a set of dies for the transitions used in this project. I ordered steel round bar in the correct size to match the corner radius of whatever transition I was making. I sectioned the round bar into quarters and welded it to flat bar to create the perimiter shape of whatever transition I wanted. Then I tapered the end of the welded unit to allow a round pipe to be forced over the end of it. I heated the round pipe with a torch and beat it onto the die. The result is a perfect match for the opening in the flange/pipe. I felt like a real blacksmith doing this.

Corbin

'95 ESI-T
Now with more power and fewer leaks



Gimme fuel...Gimme fire...Gimme that which I desire

Damn Corbin I feel like my techniques are simply elementary compared to yours now. I followed some of the others techniques for crushing the end; i used a shop press instead of a vise though. They came out Ok but not perfect. I am glad i havent began welding anything because i think that i am going to use your technique. Thanks for sharing everything about this project and answering questions for BANME!ie manifold builders like me.

Did you ever figure out your low-boost issue we discussed at the SO?

Originally posted by DarkOne
Did you ever figure out your low-boost issue we discussed at the SO?

I learned something the next morning. It is easier to figure out the problem if you open the hood AND turbos work best when the intake piping is actually connected to the throttle body. The clamp on my throttle body coupler was too big and let the coupler pop mostly off. The piping was jammed against the washer reservoir and allowing 90% of the boost to leak out. The turbo was working really hard for that 4 psi.

Corbin

'95 ESI-T
Now with more power and fewer leaks



Gimme fuel...Gimme fire...Gimme that which I desire

Originally posted by Corbin

Originally posted by DarkOne Did you ever figure out your low-boost issue we discussed at the SO?

I learned something the next morning. It is easier to figure out the problem if you open the hood AND turbos work best when the intake piping is actually connected to the throttle body. The clamp on my throttle body coupler was too big and let the coupler pop mostly off. The piping was jammed against the washer reservoir and allowing 90% of the boost to leak out. The turbo was working really hard for that 4 psi. Corbin '95 ESI-T Now with more power and fewer leaks Gimme fuel...Gimme fire...Gimme that which I desire

If you removed the washer reservour like a sane person you'd have known that sooner :+

I wish I could weld or even grasp my mind around the idea of makin a manifold but instead I will work overtime for 2 weeks or more if needed to bribe one of you to make me one and if you refuse I will kidnap you and force you to make one but either way you shall make me one lol j/k. You belittle your work corbin that is a nice manifold.

Originally posted by slippi84
I wish I could weld or even grasp my mind around the idea of makin a manifold but instead I will work overtime for 2 weeks or more if needed to bribe one of you to make me one and if you refuse I will kidnap you and force you to make one but either way you shall make me one lol j/k. You belittle your work corbin that is a nice manifold.

Get some fittings and just start going at it, thats what I did.

I don't even have a welder. I might invest and try to learn I need a downpipe too. What's a better way to start off with a tig or mig welder. I'm as green to welding as it gets lol.

Originally posted by slippi84
I don't even have a welder. I might invest and try to learn I need a downpipe too. What's a better way to start off with a tig or mig welder. I'm as green to welding as it gets lol.

Neither. Its called classes. You are going to have a hard time with a mig unless someone shows you the ins and outs and there is no way your going to learn how to tig on your own.

Originally posted by Star Turbo Talon

Originally posted by slippi84 I don't even have a welder. I might invest and try to learn I need a downpipe too. What's a better way to start off with a tig or mig welder. I'm as green to welding as it gets lol.

Neither. Its called classes. You are going to have a hard time with a mig unless someone shows you the ins and outs and there is no way your going to learn how to tig on your own.

Got ya I didn't think It was like picking up a soldering irion and going at it lol. I just took my obx manifold to a guy I know threw the buisness(I work as a counterman at a wholesale parts company) that is welding me a flange for my q45 tb that is a task that it doesn't seem hard at all if I knew how to weld and those are the things that make me wanna learn. But from what I hear welding aluminum is a lot harder then steel and you need a special welder. But anyway enough of my thread steeling.

Corbin in all seriousness have you corbin have you considered reproducing this manifold?

Originally posted by Star Turbo Talon

Originally posted by slippi84 I don't even have a welder. I might invest and try to learn I need a downpipe too. What's a better way to start off with a tig or mig welder. I'm as green to welding as it gets lol.

Neither. Its called classes. You are going to have a hard time with a mig unless someone shows you the ins and outs and there is no way your going to learn how to tig on your own.

Very True. I tried to learn how to mig myself and after about a year now, i am decent but no where near great. TIG is hard and requires skill.

MORE PICS! lol great job bro, show us more pics of the finished product on the car.