Part 25: Turbo Manifold Fabrication – My 76 Mazda RX-5 Cosmo Restoration

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Part 25: Turbo Manifold Fabrication – My 76 Mazda RX-5 Cosmo Restoration

moist young wholesome will deal with more AP let me get at youth sports promotional consideration by ATP turbo the premier provider of turbo charging components hmm as I fear there is not a whole hell of a lot of room for this turbo so I think before I decide on a final position I should probably assemble the rest of it so I’m not accidentally creating a clearance problem I’ve been buying from ATP turbo for years so when I needed a terminal for the Cosmo I called them up and ordered this this is a curette GT 3076 our point eight to t3 turbine side a little bit smaller than one would typically use on a 13 B button I’ll explain that a bit later the 3076 R is a dual ball bearing design I chose to go with an internal wastegate basically for a packaging concern and the two and a half inch Inlet to4 e style compressor housing to actuate the internal wastegate from ATP I also picked up an 11 psi wastegate actuator as well as Universal wastegate actuator bracket okay well to install the wastegate actuator all I need to do is loosen the bolts that clamp the compressor housing then I should be able to move the compressor housing into roughly the position I want it traditionally this is facing straight up and the bracket is universal so it’s designed to fit in multiple locations and looks like I want it right there okay the bracket is bolts right on and obviously I’m going to have to get some longer bolts when I assemble this in its final configuration then rotate the compressor housing back down to roughly where I want it the rod gets screwed on to the actuator there should be a jamb nut there but because this is just mock up I’m not using it and it gets slipped in and hooked onto the wastegate eventually this will bolt on but because this is just mock-up I’m just using the spring tension of the arm to hold everything in place so if I apply a little bit of compressed air you should see the wastegate work Wow it’s pretty obvious I’m going to have to lengthen this arm by about a quarter of an inch it’s under a lot of tension even with the wastegate closed and the wastegate needs to be able to open a lot more than it is from a CP turbo I also purchased this five bolt to be band adapter flange it just mounts to the back of the turbo and that’s the weird five bolt pattern to a more conventional V bathtub there’s actually no gasket between the turbo and this flange because they’re precision machined surface well it looks like even with all this stuff bolted to it there’s just enough room for the turbo right about here so well I think about that I have a flange to make just like the intake manifold plan just the first step in making this one is to first lay down a template now this is just a template years ago that I made of a 13 V exhaust flange because I had to have a bunch years ago cut out on a water jet I don’t have any of those left I just need one flange so there’s no point in sending out the CAD drawings to the water jet place for one flange in cat I drew little X’s in the center of all these holes which makes it really easy to line up the punch and just pull off the template now it’s over to the drill press now this is half-inch 304 stainless so enjoying these holes and very small increments starting with an 8-inch bit going slowly and you’ll be plenty of oil and now I’m arching the hole to the next

size up there’s a quarter in and of course like most times in life when you’re trying to push something safe to go real slow and use lots of move building the turbo manifold out of 1.5 inch schedule 40 304 stainless of course schedule 41.5 inch is actually one and 5/8 inch internal diameter so I picked up a new hole saw that fits the pipe perfectly and now it’s time to hole saw the flash nothing like a hole soft through package stainless so I’m clapping everything down really well to make sure it doesn’t move around because the bit will grab notice that I’ve screwed the stainless plate to a piece of wood that way I don’t damage the drill press deck once the bolts all cut through so unhook Oh Ariel well that sure is a nice set of holes time to start cutting the flange into shape and since I have about an inch and a half to lop off the side we’re just going to put this vertically in the bandsaw turn it on and walk away because it’s going to take about 20 minutes to cut through this yep this could take a while for right yes and now it’s just a matter of using the exhaust gasket to trace out the rest of the shape and then cut it out manually on the bandsaw table which is going to take damn near forever Wow one flange

probably should have just had that laser cut now we’ll just pop this on the engine now to position the turbo the time-honored method of positioning a turbocharger in an engine bay is to of course hang it by bailing wire now position the turbo is actually rather involved because it can’t just go where it fits because there’s a lot of stuff that has to connect to the turbo the inlet the outlet coolant and oil line of course the exhaust manifold and then the whole hot side has to be surrounded by a heat shield so especially in this engine bay that’s really tight around the area I’m just trying to position it so there’s not room around the rear section for the exhaust and especially an area where I can bring the manifold runners throat to come up just a little bit it better to hold the half inch stainless ATP turbo t3 turbo flange in the right spot in the engine bay I’ve made this thin plate with two holes that match up to the flange I’m then sandwich in the plate between the flange and the turbo and what I’ll do is weld the plate to the body of the car and then screw the flange back to it and now the plant is in a fixed position that the turbo being in the way now let me just pick this up without bending everything I just did now with my flange mounted in a fixed position and the turbo out of the way I can begin running the tubing from the exhaust manifold flange to the turbo flash I’m starting the manifold plumbing at the flange which kind of involves fitting two round pegs into a

rectangular hole so what I’m going to do is cut a notch on each piece of pipe then I should be able to fit them together at an angle heat it up and then form it into the correct shape now I can use the bandsaw what the drive is faster ha well that fits pretty well considering I did almost no measuring and cut by eye what I’m doing now is eating up the pipe so I can pound it flat so that I can make it fit the relatively retained your turbo plan get in there yeah yeah I know I should probably have a bigger torch but for the once a year maybe once every two years that I actually use this thing it does the job and it’s not economical to keep a huge bottle of acetylene oxygen around for such occasional use actually normally I just keep things up with the TIG welder but I wanted to go old school on this not too bad it’s about 92% of the way there and I think I can get remaining 8% by cold squeezing it with the light yes that’s about 95% five more to go oh hell I’d say that’s pretty good

the bevel I just ground matches up with the bevel on the pie pals and when assembled together provide somewhere for the weld to penetrate into now once this thing is bolt this back to the jig I can start laying some pipe the only one of the examples especially in this case where it has to snake through a lot of tight areas kind of involves just laying on your back for at least an hour holding up various length of pipe and then trying to figure out everything is going to lay out what I’m trying to do is keep them edible as elegant and straightforward as possible without creating very difficult and convoluted Spence before that and you know this whole process really messes with your brain because you’re working in four dimensions not just XY and Z but of course dimension is time and that’s how much time you can hold this pipe above your head before it falls and hits you in the eye although I think this front-runner the matter of 190 degrees at 145 degrees with the right length runner between it after sleeping on in the past I found that it really does help to sleep on it because your your subconscious works on while you’re dreaming what you don’t dream of laying pipe after sleeping on it I’ve figured out that I think I can do the rear runner just by using a 45 a short section of three pipe and then I’ll just have to trim this 90 a little bit to line up with the hole of the flange now that I roughly know the way I’m laying this out I can start cutting pipe so since the first 45 degree Bend is uncut I’m just taping it in place with some green painters tape this is really sticky tape but it also peels off easily and doesn’t leave any residue that will affect the welding really well we’ll hold this stuff in place I’m guessing that my Street section needs to be able to half an inch less than this piece of aluminum pipe that I’ve been using to mock up so call it about five inches yeah but five inches it looks like my next piece is going to

be a 90 and I’ll have to trim just a little bit off of it have I ever mentioned how glad I am that my bandsaw has this built-in seat these pieces are cast so the wall thickness isn’t uniform throughout and when you cut one in half sometimes the hole it leads isn’t quite regular so I’m just evening it out with the die grinder well it actually looks like this is going to line up reasonably well on the first try worst case is I cut one of these maybe a quarter inch longer so that is exactly five and a half centimeters for my next piece well that’s pretty damn close but as I suspected this piece needs to just be a little bit longer and it looks like the whole thing has to rotate that way a little now that I have all my plates cut the length and angle I’m going to tack well many of them off the car because are fun tapping at the bench then off my back underneath the car yeah I set my hair on fire right car okay now that the first runner is firmly tacked in place I should be able to remove the manifold and work on it in more convenient location on the bench I guess the only question is whether or not once I undo these bolts I’ll be able to actually get the thing off to the car with this jig in the way I think that answers my question ma’am has it tight fit now that it’s on the bench it’s going to be a hell of a lot easier to work with so as I was able to sort of show from underneath the car the second runner is going to be pretty straightforward just a matter of 191 straight section of pipe and then another 45 and I just have to shorten the length of this to bring this closer to the hole which at the same time will also raise it up so because remember it’s two angles you know it’s a combination of a

horizontal to bring it this way but then as you shorten that up it’s vertical so you also bring it up so what I’ll have to do is just put a little section under there I made a wide ass guess and chose 11 centimeters as my runner life so we’ll see how close that is well it seems my guess was pretty close now I just need to cut about an inch of runner for here and maybe another 3/4 inch on the bottom it helps a lot when you’re doing this to cut bits of pipe to various lengths that way you can try different combinations and make substitutions very easily without constantly running back and forth to the saw I think what I need to do is take about half a centimeter off of this runner here because it is really close to lining up right here and just a hair more off of it we’ll probably put me right where I want to be most band saws have this handy little holder for when you’re cutting something long like a piece of pipe that wants to tilt up in the clamp so what I like to do is just use a clamp to hold it in place then tighten this thing down as much as I can and remove the clamp and that should keep the pipe from angling off the table well after some cutting it turns out that I didn’t need a shorter this piece what I needed was a longer this piece so if I can manage to hold everything up with my hands oops that’s the wrong one okay so I did need a shorter this piece and a longer this piece there we go look how well that lines up just needs a little bit of filing and it can be tacked together after a few trips back and forth to the grinder everything fits perfectly and what I’ve done is I’ve just roughly marked the orientation because my grinding isn’t perfectly flat so it helps to know where things were in lockup when I start tacking it now before I start hacking these things together of course I have to grind some bevels for the final well to sit in one by one I’m lining up and tacking the small pieces on small pieces are in place and the tag will have moved things around a little bit I’ll put it back on the moral pole make staying fit before I start stainless moves a lot so anytime there’s any welding done the fitment needs to be checked again but it looks like everything fits just as well as it did before the first few tax so I can tack the rest and this is where it really Neal to have another person no toy always sat in four places that

just keeps the world from rocking back and forth as i weld other areas single still move a lot when you round it because of the shrinkage factor and obsessed attacks solidly that way I don’t end up with an ample that’s more than a few millimeters off when finally welded now that she’s all tacked up in self-supporting I think it’s time for a test fit on the car well I’m wrestling this thing back on let’s talk a little bit about turbo fighting now I mentioned that the GT 3076 that I’m using is 0.82 t3 turbine which is normally much more when you would typically run on 13b on the average 13b you’d probably want to be T 4.90 at the smallest depending of course on turbine trip but three suns on so small with my 3076 R is unlike a typical arc Senate bill I’m not trying to carry all the power through the entire power band what I’m trying to do is emphasize the whole and mid-range but with the smaller turbine housing all of that wonderful rotary exhaust energy is funneled through a much smaller area onto the turbine wheel increasing the velocity and force with which it hits that wheel driving the turbine wheel harder and thus bringing boost on at a lower rpm the only disadvantages that is going to become a restriction in the upper rpm range but for my application that’s not really important well she fits but it’s far from hot dog in a hallway type fit however that’s not a big deal because I have to do a bunch of metal repair on the frame in this area anyway and I’ll just make a note of it now so I can do a slight frame knotch and provide enough clearance for the heat shield that have to go around these runners of course I can’t resist bolting the turbo on and seeing what she look like self supported on the edges taxing the manifold or strong enough that they should be able to support it not bad at all so this thing is ready to finish well but there’s one task I have to do before I start and that is to make two flanges out of half-inch steel one is bolt to the engine side and one that bolts to the turbo side now there’s two reasons for that one is that the fixed steel will support the stainless steel flange once bolted in place so that’s the welding heat doesn’t warp this flange it’s still good to warp a little but it’s going to be a lot less work for the machinist if it’s only a half a millimeter instead of the first time I did this with worked like a sixteenth or eighth of an inch with Moodle and the second reason is to facilitate the back purged now a back purged just isn’t something that your girlfriend does after a night shall be ashamed of what I’m referring to is filling the entire manifold with argon gas to displace the oxygen that would normally be inside these tubes the reason I need to do this is while the outside of the well is shielded by the argon from the TIG torch inside the tubing is oxygen and when oxygen hits melted stainless steel like what occur in a well it causes it to oxidize it separates out and forms what we like to call sugaring which is the stainless steel oxides on the inside of the well the problem with that is that it causes a brutal spot so if it’s going to crack that’s where it’s going to crack by displacing all of the oxygen oxygen in the tubes with a constant full of argon

we can prevent that now my plan is to close both ends of the manifold off with those two plates and on the top plate just drill a hole and feed the argon in via a tube and then on the bottom plate drilled through matching holes to allow the oxygen to slowly pull out this is the first time I back purged something so we’ll see how that plan works my back purge rig is really simple I just took the regulator off of the MIG welder and connected it to my spare argon bottle and then using a few plumbing fittings connected it to some half-inch clear tubing which comes up to a valve so I can turn it on and off and then follows around is held in place by my workbench devil chick all the way over to the flange for the turbo side of the manifold and a simple half-inch nipple with a quarter inch NPT thread connects the horrible mild steel MIG welds are now gone so before I clean it off with the wire brushed well get to wipe down with acetone to remove all the marker marks the labels that came from the factory on the pipe the gunk that’s accumulated etc etc etc I’ll finally begin to welding but just as soon as I pulled these flanges on first now the joints in the fight needs to all be sealed off by tape so that the purge gas doesn’t leak out and then as they’re welded I’ll uncover each joint apparently the best tape to use is the screen painters tape because even if it gets more it doesn’t leave a residue I’m purposely leaving this joint here on tape so that there’s somewhere for the fair to spill out because remember argon is heavier than air it’s going to fill these runners from the bottom up before I began welding I back purged the manifold for about two minutes at approximately ten cfh just to remove all the oxygen from inside the runners then I turn the flow down to about three to four CFH just to keep the gas flowing and to keep a minor pressure inside the manifold I don’t know I have the welding current set to about 120 amps and I’m using most of that current to start the weld then as the material warms up I’m backing off the pedal a little bit to maintain my welding current at about 80 to 90 amps as to not overheat the material welding stainless is a delicate balancing act between good and good penetration and overheating the material if you overheat a stainless weld you’re going to boil out the nickel and Chrome which is going to cause you all kinds of issues because well without the nickel and Chrome it’s not really stainless anymore well after about two and a half hours

behind the torch she’s all done and she’s pretty hot it’s going to take about two more hours for its cooldown the manifold has now totally cooled to a time to pull off these plates I’m actually quite surprised at how well my little back forging scheme works because these welds came out really well ah now I’m not sure how well you can see that but looking down the runner those wells look almost ideal the other runner looks just as good good pipe alignment and about 90% penetration which means a smooth interior and everyone loves the beautiful rainbow color of a well-done stainless weld it appears the plates did their job I don’t see any significant warpage here in fact I’d say it’s perfectly flat the engine side didn’t stay quite as flat each end has moved up about half a millimeter so there’s still going to be some work for the machine shop of course and I can resist putting it out on the car about as much as a 13 year old boy could resist free internet porn we have turbo but there’s still a little bit of work to do on this manifold of course I want a smooth transition from the engine into the manifold so that means pork matching the manifold a little bit to the size of the port on the engine grinding stainless sucks so this might be a while well that’s one side now the other side thankfully off-camera because of course there’s nothing more interesting than watching me run a grinder all the turbocharger stuff is obviously a huge heat source within the engine bay especially with the high eg T’s of the rotary so all the turbocharger related components are going to need heat shields now while I was working on the manifold I realized that the one and a half inch schedule 40 pipe I used fits perfectly within two and a half inch tubing so I think what I’ll do is use the two and a half inch tubing to make heat shield for the manifold runners a really easy way to draw a straight line lengthwise down a piece of tubing is to just hold a piece of angle iron tightly on it it’ll self align and then you have a perfect line looks like my plan will work

now just mark some bolt holes I’m just going to weld some nuts to the runner to hold this thing in place so the next step is to mark my bolt holes or rather mark my position wowthat’s college at work at each point of the nut I’m putting a TIG weld called MS if I screw it up on the last well melt from the threads on the nut I got to grind it off and start over again I ain’t come really short full to vote the heat shield on so I have to cut down some longest stainless steel and six books that I have Oh and now the moment of truth it’s pretty fiddly to get these tiny bolts in but see what I can do section 4 DZ well and I am really happy with that a little bit of trimming here and then I can work on the other side a little bit of practice now so well a little bit nerve-racking aside from the slightly easier welding it was the exact same procedure for the bottom so let’s hold that in place well that really seemed to work out well now obviously the other side is the exact same procedure so through the magic of editing the next time you see this thing the heat shield will be done I finished the front runner heat shield off-camera so let’s put this thing back in the car and make sure she’s built it because clearance around this area is kinda tight I still need to build a heat shield for the turbine housing but what I’m going to do is wait on that until I have the downpipe in place simply because I’m not sure how things back there are going to line up and look and I would hate to spend all that time fabricating something of difficult to work eighteen gauge stainless sheet metal only to have to cut it up and modify it and when I find out that say a v-band clamp doesn’t fit but it does seem appropriate right now to toss the turbo back on so I can bask in the glory of some promised centrifugal compressor fed forced induction with that it looks like we’ve reached the end of episode 25 first I’d like to give a huge thanks to ATP turbo for helping me out on the turbocharger and some of the other stuff that I used in this episode I’ve been buying from ATP turbo comm for years and you should too so what’s next for episode 26 well I honestly don’t know I’m kind of at a point where I can go several different directions I can continue on with the rest of the exhaust I could bloom up this wiring harness I could por-15 the floor I could fix the rotted out frame or maybe start working on what I’m going to do with the front subframe and

so not sure what I’ll do guess you’ll just have to wait and find out