Ok.. im going to make a documented walkthrough on how to make your own manifold for turbo application..
The current test prototype manifold is goign to be for my GA16DEt project...
Parts needed :
1 - manifold flange
2 - turbo inlet flange
3 - 6-7 weld-els 40 gauge (i got 6-90° bends)
4 - Some straight pipe (still 40 gauge)
5 - recipricating saw, to cut through metal
6 - Mig / Tig Welder
Here goes..
1 : Start out with your flange for the manifold.. the flange that attaches to your head..
2: get a good idea of how you want your turbo to be mounted.. and then you can get a pipe layout of how it should look... now me, My piping is going to be 1.5" in diameter, so ironically enough, i found a hose that would match that size, a Vaccum cleaner suction hose (for attachements and what not on you vaccum cleaner..), well i placed them against the manifold, for a good idea of how long each one should be.. and i came up with this.
3: After getting a measurement of piping size/length, cut the piping, so that they will merge into 1 nice collector.. you can always cut and weld the real pipe so that it will work better..
4: Duct Tape the piping to the manifold, to get a relative idea of how the metal pipes will have to be bent.... note, due to the piping not Completly being solid, like metal, this is only a rough draft..
[b]Please stay posted, I will be updating this with more information, as i have more information to post.. im waiting for metal exhaust piping right now..
Coming soon : Making your own Downpipe, intercooler piping, and Turbo installation
i usually just test out a bunch of different designs by tacking and test fitting.....but that's definately a different way to mock things up, might save some time *hint* you might want to try those PVC pipes/bends from a hardware store. they come in different IDs and radii, and are a little more stable .
as for your pipe diameter.....1.5 in. ID is quite large.....you may want to consider a smaller dia. ID for a tubular manifold that will power a T25 turbine. also, you can save considerable time and $ by using pre-bent mandrel bends instead of bending your own.
Chuck....this is great! However, I feel most of the people that are about to turbo their 1.6 don't have the skills or knowledge required to do something like this, or, well, to do it properly. I'd still suggest a tried and tested manifold simply because an average joe making a manifold may not produce postive results. Flow patterns need to be maintained
well i considered buying mandrell bends. but, im looking over the long run, plus its hard as heck to find smaller piping.. i ordered 7ft of pipign of JCwhitney.. for like.. 19$ shipped.. and not only that, i measured the holes on the exhaust manifold, and they are a peachy 1.375... the same as the interior of the exhaust pipe..
BTW: my BRAND NEW T25 turbo is coming in the mail today.. oh joy
Yes guy!!! I have a machist meeting with me tomorrow to discuss making all new intercooler piping and dp (he has access to cnc machines, mandrel bender, sandblasting, powdercoating...) and he is def going to see this thread. Thank-you!!
So if I wanted a nice equal length manifold, there's nothing more to that than having the same length pc's with curves that will fit in underhood space I have? I may as well ditch the log manifold since I need a dp and have a guy to do it without killing the pocket book. I just hadn't thought about it, thanks again.
for real.. im going to have access to a cheap pipe bender.. but.. it will do the job.. like i said.. i will update as i have something to update.. but id love to see other people share the passion in making there own.
well i considered buying mandrell bends. but, im looking over the long run, plus its hard as heck to find smaller piping.. i ordered 7ft of pipign of JCwhitney.. for like.. 19$ shipped.. and not only that, i measured the holes on the exhaust manifold, and they are a peachy 1.375... the same as the interior of the exhaust pipe..
BTW: my BRAND NEW T25 turbo is coming in the mail today.. oh joy
Better watch the tubing thickness as well, just any "tubes" from JC whitney is probably going to crack apart real quick. I would recomend scedual 40 weld-els or at least some thick 12 gauge tubing. A turbo manifold has to support the turbo so it has to be strong.
Mike
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chuck, its good that you are laying out your exhaust manifold, but keep in mind the minimum bend radius of your bender. I used prebent weld-els (I believe they had about a 1.25" radius) and I still found myself cramped for space in some spots. How are you planning to make the collector to merging the 4 pipes together?
-dave
alot of cursing, welding, and cutting.. thats how..
no, im going to get about 4 pieces of 2" piping. and cut them up, so they will merge into one piece, and have 4 pipe outlets still.. if that makes any sense.. just like any collector.. only hard part will be making precise cuts.. we shall see.. im goin to document it as best i can
you buy the weld els pre bent in 90/45/180 degrees... I used schedule 40 els. I think that's what's on the right in Javier's picture. I added a picture of my manifold during the mock up stages.
-dave
Last edited by dave_f : Mar 23rd, 2004 at 05:43 PM.
*hint* you might want to try those PVC pipes/bends from a hardware store. they come in different IDs and radii, and are a little more stable 
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