Building A Turbo Manifold...Step By Step

Over the next few weeks I'm going to go over all the steps that I follow while building one of my turbo manifolds. I'm always being asked just how I build them, and I've never seen an in-depth write-up on how to make one, so now you're getting one. I will be making this manifold during my break time at work, so progress will be slow, but you will have a complete guide to building a manifold.

Day 1: Prepping the Materials
On the first day I gathered all the materials that I will be using in this manifold and prepared to clean them all. This is a very important step if you want to have a professional quality manifold.


Here is a 90 degree 304SS elbow as I receive them from my supplier. It has ink on the surface along with oils and grease residue from shipping. This will need to be cleaned with acetone to have a good base for the next step.



Here we see the elbow after having been wiped down with acetone. The surface if free of any contaminates, but is not the most appealing, so a mechanical cleaning step will need to be used. This will bring out the luster and beauty of the stainless steel, but will also allow for very nice coloring to be seen after the parts have been welded together.



This is the elbow in its final cleaning phase, and is ready to accept a clean weld. There are many different ways to obtain a finish similar to this on the elbows, but mine remains a trade secret.



Here we have the stainless steel pipe that we will use to make both the collector and parts of the runners in our manifold. This too is covered in ink and oil so it must be clean.



After cleaning not much of a difference is seen, but DO NOT skip this step. You will kick yourself later if you do.



And here is the part after going through a mechanical cleaning step. This is the one process that really makes the parts shine.



Next we will move onto the flanges in the build. No matter how clean you think the flanges may be, do yourself the favor and clean them again. When I first started making manifolds this was one of the biggest mistakes I made. Assuming that the flanges were clean because they were already shiny.

Here is the head flange followed by the turbo inlet flange.



I just happened to take a picture of a B series flange that I had on me, but I will be building a manifold for a SR20DET.



If you are not gong to use the parts you just cleaned right away make sure you store them in a clean location. Here are a lot of the parts being put away for tomorrow.




Now I just so happened to have a little more time today than expected so I started to cut my collector. There are a million ways to do this, and a million different jigs to use, so I'll leave it up to you to figure this out of your own, but I will give you a tip. When cutting your pipe I’ve found that after the first cut you have to rotate the pipe just beyond 90 degrees. For some reason if you rotate the part exactly 90 degrees the collector doesn't meet up cleanly.
Here is just one of the four parts to my collector.







And that’s all for today. Tomorrow I will try to finish my collector and will so you how I prep it for welding and the techniques used to do so.

A teaser of two manifolds that I'm working on. At this stage I’m just adding wastegates to the manifolds. The far manifold has an interesting location, it should work out nicely.



And the end result of the process. It may take a little longer to go through all the steps, but it is definitely worth it.





1. prepping the elbow. to make it look like this simply use a SS wire brush (known the trade as a power brush) in a drill press. and run it on a med speed. manually run the elbows around the spiingin wire wheel. we do this to all our elbows here
2. making the collector. there have been several threads here that showed this in the past. basically 3 methods. band saw, abrasive saw, or mill. you need ot make a jig. you need to figure out what angle you want your collector to be. make first cut, rotate, make 2nd cut. ( heres a BIG hint-the 2nd cut is a ghost cut)

Haven't had time to go over collector making, but I will be doing it tomorrow. In the meantime, heres a little update from the last manifold and a friends car I am building.

ready to cut then weld:





And my friends car. I've built the engine and head, as well as fabbed up the IC piping, turbo manifold, and piecut downpipe. Hope you like.







And the manifold prior to install (BTW, its an old manifold being modified):



Well I finally pushed through and completed another manifold today, so I was able to document the entire process. I had to take the day off to do so, but I think it was worth it. Today I will show you how I cut and prep the collector for welding, Enjoy!

Here I am going to show you the jig I made for my chop saw. I am going to assume that the most commonly available cutting tool for the amateur fabricator is a chop saw, so I’m demonstrating with it.

Here is the Jig, it is very simple, allows for infinite angles and depths of cut, and seems to work just fine for the application.









Here is a piece of pipe loaded in the jig. As you can see I’ve marked where the end of the pipe rests so that all four pipes will be the same. Once it has been loaded the first cut can be made.









The next step will either make or break your collector. You must turn the pipe just slightly past 90 degrees in order to create a collector that merges correctly. I will explain more now.

Here is the pipe turned:



This would be a 90 degree turn as being shown by the perfectly level surface from the previous cut, this is not ideal.



Here you see the ideal angle to cut, just slightly more than 90 degrees. You can see that the bubble in the bullet level is off to the right.



And here is the pipe after making the cut:





a few more pieces:



Here you can see what you are trying to avoid. While the collector looks very close to being perfect, light can be seen from underneath. If you have this problem it simply means you need to turn your pipe slightly more the next time you cut a collector. This piece is still salvageable; it’s just going to take a little more time to reach a perfect fit.



Wow, I feel like I kinda over-killed my jig. But for me it was easier to CNC two halves of Plastic to hold the pipe at the right angles. I didn't cut the jig with a band saw, it came off the cnc as pictured. The pictures tell the story.













Well i'm slacking on finishing this thread, but heres a bump and a promise to finish it within the next two months

And heres one of my 1.8t manifolds after 1 hour of driving time. Pulled while removing the trans, byby 3rd gear... and then 1st gear