Building the GTR's Merge Collector (Lessons Learned)

Ajouté : 2026-05-11

[00:00:12][music] [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] >> Hey everyone, welcome back to another video.

[00:01:31]So, in last week's episode, I introduced this. And this is my friend Russ from Excel from Accelerated Performance and his wife Katie's new R33 GTR project.

[00:01:45]It's powered by a V cam equipped RB26 and I am building a turbo system for it.

[00:01:52]So, with that in mind, we need to start on it. And where do we start?

[00:01:58]Well, for me and the way that I prefer to build these systems, I like to start with the turbo header first. And in building the turbo header, the first thing that needs to be built for that is the merge collector. Now, to me, the merge collector is kind of the heart of the turbo header or the exhaust manifold.

[00:02:15]It dictates A, where the component aside from the turbo that takes up the most space will be located and B, the architecture of the collector kind of dictates the routing of all of the primaries.

[00:02:28]Now, on this car, once we get the collector built, I can then locate the turbo and by locating the turbo, that will kind of dictate the routing that the primaries take, if they need to make their way around any other components, as well as the wastegate location, the initial idea for the downpipe routing and so on and so forth.

[00:02:53]If the turbo is in its home and I can build the header that way, well, it dictates a lot of how the rest of the system is going to come together. And that leads us over into the fab room, where in the intro montage of this episode, I got my band saw all converted over to do some collector cutting.

[00:03:12]So, I've shown my collector cutting setup multiple times in the past, but if you guys haven't been around or don't remember exactly what's going on here, well, this is old trusty.

[00:03:25]I built this collector cutting fixture for an old chop saw that I had and then converted it over to be used in the band saw. You can see that she is quite an ugly duckling, but the aesthetics aside, this collector cutting fixture has cut hundreds of collectors at this point in time and continues to do its job very, very well. Now, the way that this collector cutting fixture works is quite simple. It is just a piece of 2-in schedule pipe that I drilled a hole through and welded a nut, so I have a set bolt assembly right here.

[00:04:00]And I can feed anything up to 1 and 1/2-in schedule pipe or 2-in tubing through this collector cutting fixture and make my cuts, figure out the angles and so on and so forth.

[00:04:14]Now, in regards to angles, as you are cutting a collector, you are rotating the pipe in the cutting fixture. And you cannot rotate to just an arbitrary angle as that won't really serve you any good.

[00:04:30]So, that is where this guy comes in right here. This is an analog tube or pipe rotation gauge from Trick Tools and I've used this for many, many years to cut collectors just like this.

[00:04:43]So, you guys can see that we have essentially a 360° numeric register around this and I'm not going to do it right this moment since I'm indexed at zero where I want to be, but as I loosen the set bolt, I can put this magnetic angle or angle gauge on this right here and rotate the pipe around to the angle that it needs to be. And that brings us to the angle of rotation between collector cuts. How do you figure those out? How does it make sense? And this is probably the most complicated or at least the most intimidating, I should say, portion of cutting merge collectors.

[00:05:25]That being said, I do have a quick and easy way that you can figure out at least the base rotation between collector cuts for any merge collector that you need to cut. And it all boils down to a simple math formula in my manifold book right here. So, what we have for the collector rotation formula is a simple algebraic equation. And what this does is as you plug the numbers into it and do the formula, it will spit out the base rotation that you have for any merge collector that you need to cut. You can use this for 2-in-1, 3-in-1, 4-in-1, 5, 6, 7, so on and so forth. Any collector or any collector that you need to make, this formula will tell you the base rotation that you need to make between cuts to make the pieces fit together.

[00:06:17]So, if we use a 4-in-1 collector as an example, where the base rotation for those pieces is 90°, if I take my ratchet right here and use this as an example, if I make my first cut with my angle gauge set at 0°, well, the rotation to make the second cut should be 90° in order to make everything fit together correctly.

[00:06:40]So, with that being said, let's take the calculator and plug some numbers in and I'll put my money where my mouth is.

[00:06:47]So, we have X equals the number of pipes minus two times 180 divided by the number of pipes.

[00:06:55]So, on the calculator here, we have 4 minus two times 180, which equals 360 and then divided by the number of pipes, divided by four, there we go, 90°.

[00:07:12]>> [snorts] >> So, this also works for just about anything else.

[00:07:17]Let's take a 3-in-1 collector for example, which the angle of rotation or the base angle is 60° for those.

[00:07:25]So, if we take 3 minus two times 180 equals 180 and then divide that by three, there you go, 60°.

[00:07:38]So, this is a very handy formula to use and by all means, feel free to save it and use it in your manifold constructions. But for the sake of this collector, I'm making a circular 6-in-1.

[00:07:52]And this collector or this collector formula is readily applicable for that.

[00:07:56]So, again, if we take 6 minus two times 180 is 720 and then divide that by six, we end up with 120° for the base rotation for the 6-in-1 collector. Now, I've reiterated the base rotation portion of this a few times throughout the explanation of the formula. And why that is important and why it is noteworthy is not every saw is the same and not every angle that you're working with here is based off of kind of a plum true right angle and nothing is perfect is what I'm getting at.

[00:08:37]So, with my saw, my cutting fixture and everything else I have here, I have a plus 5° variance that I factor into the cuts that I'm making. So, rather than using a 120° rotation like the formula spits out, well, I need to add 5° to that. So, 120° becomes 125°.

[00:08:59]The 60° that we use as an example for a 3-in-1 collector becomes 65°.

[00:09:05]90 for a 4-in-1 becomes 95 and so on and so forth.

[00:09:10]All that being said, you can use that formula as a base to get you what the foundational number is, but you should always test with either uh metal schedule pipe or PVC is another fantastic option that doesn't put a whole lot of stress and wear and tear on your tooling and allows you to make a bunch of quick cuts and figure out what the actual tailor angle needs to be for the pipes that you're cutting. So, with all of that being said, let's go ahead and cut the six collector pieces and then we can go down the rabbit hole with the whole prep side of things.

[00:09:51]>> [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] >> Well, I'm actually going to try a new step in my prep process, and I'm going to incorporate my vibratory bowl into this.

[00:11:45]Now, if you guys haven't seen the vibratory bowl, it is a >> [bell] >> tool that this whole upper black portion will sit and vibrate around.

[00:11:56]And it has this finer grain media in it, if you guys can see that right there.

[00:12:04]So, what I'm going to do is put these collector pieces into the vibratory bowl, kick it on, and let them do [snorts] their thing in here for a little while, and we'll see what happens.

[00:12:19]Ideally, it'll take some of the residual burrs and stuff like that off, and begin prepping the surface of these pieces.

[00:12:28]I don't know how well it's going to work. I've never done it on a collector that I'm actually going to put into service, but I think it's at least worth the old college try. So, get this sealed up, get it kicked on, and then I can go get some lunch, and work will be happening while I'm not here.

[00:12:47]And hopefully, by the time all this is said and done, after maybe an hour or two, these things will be good to finish the surface prep process.

[00:12:56]The deburring will be done completely, and then we can move right on to welding. So, we'll see what happens if I hit the switch.

[00:13:06]There it goes. We'll see what happens.

[00:13:09]All right.

[00:13:11]So, oh, these pieces have been in here for about an hour and 20 minutes at this point in time. If I pull the pieces out, they are cleaned up a little bit. I didn't expect a whole lot, and didn't really get a whole lot from this, but I think they're good enough at this point in time to take them over to the wire wheel, and get them shined up, and then tack everything together.

[00:13:45]>> [music] [music] [music] [music] [music] [music] [music] [music] [music] >> Well, unfortunately, my vibratory bowl experiment went poorly. Everything pretty much went wrong with it.

[00:15:12]And the surface finish on this collector is not acceptable, nor is kind of the nastiness, if you guys can see it throughout the weld there. Looks like a bunch of contamination through it.

[00:15:25]I tried to brush one of the welds to see if I could salvage it, and I think this collector and its surface finish is just a lost cause.

[00:15:33]Now, you can see in contrast to this little butt weld that I did right here, all of the colors and the more brilliant shiny surface finish.

[00:15:44]I should have just stuck with my traditional surface prep process, but it is what it is at this point in time. So, thankfully, I have enough material here that I can cut a new collector, and now I can make a mental note to never do this again.

[00:16:01]So, I'm not going to make you guys sit through that entire process again. So, with the power of YouTube magic, we have one bum collector and the test piece, and with a snap of my fingers, and just like that, the R33's new collector is all fabricated, tacked together, and ready to be welded.

[00:16:21]So, [snorts] seeing these two collectors side by side, you can see how much shinier and more brilliant the surface finish is on the new collector as opposed to the first rendition.

[00:16:32]And this is still a good collector. It can still be used for something, and I think what I'm probably going to do is to put it onto a turbine flange, and then give it to one of you guys.

[00:16:44]So, I'm not sure exactly how I'm going to do that just yet, but probably in next week's episode, I'll make an announcement about that, and one of you guys will end up with your very own 6-in-1 V-band collector.

[00:16:57]But with that being said, the only thing to do at this point in time is to weld this collector up. So, let's go ahead and do that, put some pretty colors down onto it, and get the collector ready for the next stage of this build.

[00:17:15]>> [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] >> Well, with the GTR's merge collector welded together, we now need to trim it so it fits to the 2-in schedule pipe that the elbow leading up to the turbine inlet flange will be comprised of.

[00:18:41]So, what I do for this is I take a piece of 2-in schedule pipe, like this one here, and I will set the collector inside of it, then scribe a line around it, cut on that line, and from there I can flare the outlet of the collector to match the diameter of the 2-in pipe. So, what I like to use to flare collector outlets like this is pretty simple and pretty rudimentary, but pretty effective.

[00:19:10]And what it is is generally this cut-off trailer hitch ball right here.

[00:19:17]So, this is a 2 and 5/16 ball that I will place into the collector outlet, and hammer down upon it until the collector outlet is flared and matches the correct diameter.

[00:19:30]Like I said, it's pretty crude, but it does work pretty well.

[00:19:54]>> [music] [music] [music] >> Well, with the inside of the R33's collector all welded, it's now time to start figuring out the turbo location as the turbo location directly dictates the rest of the form of the collector.

[00:20:20]So, to figure out turbo location, I'm going to use my engine support bar and then my turbo locating apparatus that I have attached to the turbo here. So, this is a piece of I believe it's 5/8 all thread that I welded to a tab and the tab bolts right here to a little two-bolt flange piece down in here. Now, this is inverted from the way that the turbo will normally sit due to the fact that the inlet of the turbo or the inlet of the center cartridge for the oil feed does not have a two-bolt flange. It's just that single fitting right there and I believe if that fitting is removed, then the warranty for the turbo is null and void.

[00:21:08]So, we're not going to mess around with that.

[00:21:11]I just rotated the center cartridge upside down and my little two-bolt flange bolted up perfectly.

[00:21:18]So, at this point, what I need to do is to feed this piece of all thread through whichever opening on the engine support bar it needs to sit in, which I'm assuming will be this farthest right one right here.

[00:21:33]And then I can move the engine support bar around as needed to get the turbo into the location or the rough location that it will sit in.

[00:21:41]From there, I can kind of eyeball where everything's going to sit in the engine bay and I also have the turbine inlet flange clamped to the inlet of the turbine housing.

[00:21:54]So, at that point, I can take the collector and I can take some of the 2-in schedule pipe stuff that I have here and start playing around with how things are going to sit, how they're going to be attached to one another and before too long, we should have a pretty good and pretty concrete idea of the way that this collector, the rest of the collector, needs to come together.

[00:22:15]>> [music] [music] [music] [music] [music] [music] [music] [music] [music] [music] >> And just like that, the GT-R's merge collector is completed or at least the base form of the merge collector is completed.

[00:24:39]And here's what we have ended up with.

[00:24:41]So, we have our circular 6-in-1 to our 2-in schedule pipe elbow coming up to the HPT 6266 V-band turbine inlet flange.

[00:24:54]The 6-in-1 collector, as you guys saw, I flared to fit the 2-in piece of schedule pipe and the collector is schedule five, whereas this elbow is schedule 10. So, inside of here, you guys probably it might be difficult to see, but I did some grinding in manipulating of the schedule 10 elbow, so that way it's as smooth of a transition as it can be from the 6-in-1 to the 2-in to the 2-in elbow.

[00:25:21]I'm happy with the way this collector has came out and most importantly, now that the collector is done, we can shift focus over to the car and start figuring out the final turbo position and then where this thing will sit and how the primaries need to be designed.

[00:25:40]So, I think that will be or those will be tasks for next week's episode. I think we covered enough in this week's and some do's and don'ts with collectors, cutting collectors, making collectors, most importantly surface finishing them and uh like I said, we learned what not to do with my deviation from the normal prep procedure that I use. That is not something I will be doing again and even after all of this time, I can still learn new lessons, still learn new ways to do things and like I said, still learn what not to do. But with that being said and a big piece of the GT-R's uh new exhaust manifold completed, that'll be about the end of this one.

[00:26:27]So, thank you guys as always for coming along on all of these different journeys and all of these different adventures with me.

[00:26:34]I'm excited for the GT-R project. I hope that you guys are as well. I'm excited that the collector is done and now we can move on to actually running pipes from the nice head flange to the collector and turning this idea for an exhaust manifold into a reality.

[00:26:52]We have a lot of cool things to do on this car and the exhaust manifold is just the beginning. So, I hope that you guys are looking forward to the rest of this turbo system build.

[00:27:01]And like I said, working on a car that I've never worked on before, but always wanted to, well, that's a very special opportunity that I have.

[00:27:11]One that I feel very fortunate to be trusted with to build this system and one that I'm certainly not taking for granted. So, from the bottom of my heart, I thank you guys very much for tuning in and coming along on this journey and on this adventure with me.

[00:27:25]And by the time that this car is done, it'll be something very special.

[00:27:29]But with all of that being said and before I ramble on incessantly, that'll be the end of this one.

[00:27:35]So, as always, be sure to subscribe, leave a like, leave a comment and check out the website for manifolds and merch and all things good that way, including my retro collection.

[00:27:46]Right now, I am adorned in purple haze apparel. I have my purple haze hat on camo print on right now as well as my purple haze flannel.

[00:27:57]So, if you are interested in your own purple haze hat, flannel or t-shirts, hoodies and so on and so forth in purple haze or any of the other three unique colorways that the retro collection is comprised of, well, you can find all of those in the retro collection link in the description below. If you see anything there that pops out at you, by all means, feel free to pick it up, wear it around and sport the good BPA name.

[00:28:23]But if nothing there does appeal to you, that's okay as well.

[00:28:26]Hopefully, I offer something in the future that does speak to you and that you would like to add to your collection.

[00:28:32]But with all of that being said and a big step taken forward on the GT-R project, that'll be the end of this one and I will see you guys in the next episode.