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Registered:
May 2002
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Making a custom manifold
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Tue, 14 January 2003 09:36
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I'm going to make my first manifold for my 1G gte. I've heard a lot of stories about super special designs that make a huge difference. Lengths, curves in the piping etc.Any hints or suggestions would be much appreciated.
The original cast manifold looks absolutly shocking!! theres sharp turns and bits every where. Is this supposed to be this way or are they just crap?
As I said any hints or suggestions will be greatly appreciated
Cheers
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Location:
Mildura
Registered:
May 2002
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Location:
Canberra
Registered:
May 2002
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Re: Making a custom manifold
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Tue, 14 January 2003 10:57
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TD42T: That's some pretty creative stuff there! 
How did you machine the adaptor plate to change from the 1J ports to the 7M ports?
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Location:
Mildura
Registered:
May 2002
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Re: Making a custom manifold
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Tue, 14 January 2003 11:55
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After cutting the lower intake in half(which changes were the runners are a little) i lined it up and the middle 4 were very close.I then cut the end 2 off the flange(head side) and turned them around so they bent the other way.
Then I used a hole saw and Die grinder to cut the ports into the adaptor.
Clamped it together and welded it up.
Very easy really, but making everything else fit takes the time.
marty
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Registered:
May 2002
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Re: Making a custom manifold
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Tue, 14 January 2003 21:45
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I thought the stnd manifold was cast which you couldn't weld?
Any other tips?
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Registered:
May 2002
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Re: Making a custom manifold
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Wed, 15 January 2003 06:47
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Bump
I need all the help I can get. I want to avoid a frakinstien manifold.
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Location:
Mildura
Registered:
May 2002
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Re: Making a custom manifold
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Wed, 15 January 2003 09:06
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Manifold is cast but it can be welded.
marty
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Location:
NSW
Registered:
May 2002
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Re: Making a custom manifold
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Wed, 15 January 2003 10:51
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I think Japspec is talking about an exhaust manifold here...(?)
And marty is on about intake....
Please correct me if im wrong........
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Registered:
May 2002
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Re: Making a custom manifold
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Thu, 16 January 2003 01:31
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Yeh thats right traction but even still I didn't think you could weld cast intakes either.
Hey traction, can you give me any pointers on making up a single turbo exhuast manifold i.e length of runners etc
By the way how is your car, hilux's go off! 
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Making a custom manifold
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Thu, 16 January 2003 04:11
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Personally I think it's easier to start again, go get a plate cut out to suit your gasket (or do it yourself!), get some pipe/bends in the correct diameter/length, build a plenum either out of pipe or by folding up some metal, and start welding. It's not really that hard once you get started, and saves a bloody fortune over getting others to do the same thing - plus for some of us its kind of fun
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Location:
Mildura
Registered:
May 2002
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Re: Making a custom manifold
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Thu, 16 January 2003 06:51
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Sorry I thought you were talking intake 
Yes you can also weld cast exhuast manifolds but it isn't easy.
Marty
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Location:
NSW
Registered:
May 2002
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Re: Making a custom manifold
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Thu, 16 January 2003 08:41
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japspec,
try and build the runners equal length, about 12-14" long, and use a similar amount of bends in each runner. Also try and get the runners to flow into a GOOD collector, ie, so that the 6 of them come into the collector parrallel to each other. I couldnt get mine that long just cos with 2 turbos you got bout 1/2 the amount of room to work with, but they are about 8" long....
Marty,
um, TD42T....please tell me u got a GQ patrol motor in your supra..turbocharged!!! 
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Registered:
May 2002
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Re: Making a custom manifold
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Thu, 16 January 2003 12:38
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Thanks for the help guys.
I had an idea about making a kind of extractor type set up to run into the turbo i.e alining the piping to match firing sequence. Giving the initial firing cylinder the "master pipe" which all the other pipes meet in succession down the line in firing order. Continuing the flow of gasses into the turbo. May create a more efficient spool up?
I get the welder this weekend so may make a start.
Cheers
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Making a custom manifold
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Thu, 16 January 2003 20:50
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From what i know, which isn't a lot really, there is two approaches to building turbo manifolds.
The first is to tune them such as what japspec was saying. This rely's on developing a smooth flow of gas through the manifold/turbo. I imagine that it would be much more efficient high RPM. At low RMP, the hysteresis (read turbo lag) inherent in this system means that you will sacrifice low RPM power.
The second method is to make them as short as possible and rely on the pressure as the exhaust gas immediatly exits the engine. This allows the turbo's to spool up a bit quicker as the pressure differential comes in high pulses rather than a gradual build up. If you have a look at the standard setup on the 1G engine (and most other twin turbo engines), this is the approach used. Great for power at lower revs, but inefficient at high RPM.
I am no expert in Turbo manifold design, but did study fluid dynamics at Uni and know that you can't just chuck it all together. My advice is to visit an automotive book shop and get a good book on manifold or turbo design and make an informed decision before you start waving a welder around.
But then again, I'm an engineer and get told everyday that complicate simple problems.
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Location:
NSW
Registered:
May 2002
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Re: Making a custom manifold
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Fri, 17 January 2003 02:28
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Anthony,
Actually, if you look at a standard 1G manifold, it comes off the head, turns 90 degrees downwards for about 5" then does a 180 degree turn into the bottom of the turbos. It really isnt a bad design.
On the other hand, if you look at a 1J/2J or 7M manifold, these are all "stump" or "log" manifolds so to speek, where the gas takes the shortest possible route to reach the turbine. As you were saying, this gives great low down response, hence the reason why 1/2J's are monsters off the line.
My 2 cents anyway 
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Location:
Mildura
Registered:
May 2002
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Re: Making a custom manifold
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Fri, 17 January 2003 03:44
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GU coil cab actually
marty
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