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Discussion Starter · #1 ·
I started to try and make a manifold... This is what I got so far...

It took me about 6 hours to get to this point and its hard work! All my muscles are aching and its tuff, but I have confidence I can do it, I just wish I had a better grinder and a nice band saw or something to make nice neat cuts. The cutting with a chop saw is not too bad, its all the grinding that sucks, I have doing it all with a chop saw and a die grinder. Grinding small pieces on the chop saw is painful!

John
 

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when will they be on sale?:lol:
 

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BOOOSTTTT LEAKKK!!!!!!!!!!!!! :nono; lol, i like how your going at this yourself, looks like a good start keep up the good work john and good luck...
 

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Can somone explain the advantage of equal length manifolds on a turbo? - in my understanding the more volume you have between the ex valve and turbo the more cooling of the exhaust gases can take place and thus the energy to drive the turbo is reduced. Not to mention the now tortuous path the gases have to take.
 

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the frequency of the exhaust pulses hitting the turbo is alot better, more even. JZW is also running alot more pwr than stock, once you start to have to upgrage the turbine housing to reduce back pressure the manifold tubes are next.
 

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Discussion Starter · #8 ·
Bingo, the back pressure is the biggest gain from what I understand and from what I have heard and read, until you are over around 350bhp, the stock one works about the same...

The main reason I need one is to relocate the turbo so I can keep my ac in the car. If I lost the ac, I have pleanty of room for a 3071 or 3076. A nice flowing tuned header should lower back-pressure, increase flow and spool-up and compliment things like a ported/polished head and a larger turbo.

I have also heard some tubular manifolds will actually flow worse than a stock cast iron manifold. You really do need to plan it out, make everything flow well and use a good collector. Short radius's hurt the performance a lot.

My lawnmower is starting to sound good...:cool:

John
 

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Discussion Starter · #9 ·
Marks900SE said:
You doing stainless?
That one was mocked up in mild steel schedule 40, easy to weld and it would be as strong as a tank, no bracing required. Now that I have an idea of how and what I want to do, I will break the tac welds and form it up in schedule 10 304 stainless weld ells... I will have to brace the turbo with the thinner metal and I will also have to be much more carefull on my welds...

John
 

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John Z Williams said:
That one was mocked up in mild steel schedule 40, easy to weld and it would be as strong as a tank, no bracing required. Now that I have an idea of how and what I want to do, I will break the tac welds and form it up in schedule 10 304 stainless weld ells... I will have to brace the turbo with the thinner metal and I will also have to be much more carefull on my welds...

John
Thats what one of the guys near me did. He made one out of mild to get the design right, the placement right, and make sure the collector is right. Gonna coat it and use it while we create the stainless version. With how we set his up, he got a lower profile radiator fan that gave gobs of room. Another GT3071 is gonna be on a ng900 soon.
 

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Discussion Starter · #11 ·
I have decided I will have to go to a low profile fan too, there is just not enough room for the big stock one. I will probably go with the two 12". You need at least 14" one from what Jak says, they tried one 12" one and the car would over-heat at a stop with ac on in the summer.

John
 

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John Z Williams said:
Bingo, the back pressure is the biggest gain from what I understand and from what I have heard and read, until you are over around 350bhp, the stock one works about the same...

The main reason I need one is to relocate the turbo so I can keep my ac in the car. If I lost the ac, I have pleanty of room for a 3071 or 3076. A nice flowing tuned header should lower back-pressure, increase flow and spool-up and compliment things like a ported/polished head and a larger turbo.

I have also heard some tubular manifolds will actually flow worse than a stock cast iron manifold. You really do need to plan it out, make everything flow well and use a good collector. Short radius's hurt the performance a lot.

My lawnmower is starting to sound good...:cool:

John
actually in many cases the cause for the high back pressure it not the manifold itself, but the tight tubine housing and too poor flowing WG.
For example in one saab I tested the other day, the back pressure was measured more or less the same with std manifold and a tube one.

Also it internet talk the better/lower spool if often taken for granted even though in many cases the end result is just the opposite. This becuase the std manifold "pipe size" is so much smaller and it will indeed work quit well until the flow over rides its capability to flow.

I my car and all of the cars I know with GT30, GT28 aso, the back pressure will increase much above the boost regardless of manifold type. Of course the more hp you push the more in trouble you'll will be with the std. manifold, so this was not a marketing speach for it.
 

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Discussion Starter · #13 ·
Yea, that is what someone else stated on the back pressure and flow of the stock manifold vs. tubular manifold. I was hoping a tubular manifold would show more gains with more bhp, but it sounds like the wast-gate is the main issue.

I think I will open up my waste-gate a little more this time and see if that helps the situation.

John
 

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As your going to the trouble of putting a header together why not put a port for an external WG on the collector? It's a far better solution than the stock internal WG.
 

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Don't rule out the use of a pusher-fan...
There are a LOT of guys that run a small-ish fan inside the engine-bad, and then run a bigger "helper" fan outside. saves room, and works just as well.
 

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could also ceramic coat the headers but thats $$
 

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Wrap them! - it's cheap and it will retain the heat you loose due to both the extra surface area and the lower heat retention of the thin walled tube vs the thick casting
 
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