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Good Twin Turbo Manifold Design?


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So are you the guy that trying to sell it on ebay?

No, but I was looking into buying it.

I would say no, due to seriously unequal runner length. If you were planning on replicating it, copy the back half where they're all a lot shorter and use that. It still wouldn't really be ideal but it'll be a lot better than that.

Then I'll avoid it all together. Thanks for letting me know. I've seen a few manifolds, but this is the only one I ever saw for sale, and it looks nothing like the others I've seen.

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I would say no, due to seriously unequal runner length. If you were planning on replicating it, copy the back half where they're all a lot shorter and use that. It still wouldn't really be ideal but it'll be a lot better than that.

 

What seriously unequal runner length? The manifold runners are about equal in length. What you are looking at is the equivalent of the "downpipe" of a single turbo application. The "seriously unequal" pipes connect to the exhaust housing after the turbine.

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What seriously unequal runner length? The manifold runners are about equal in length. What you are looking at is the equivalent of the "downpipe" of a single turbo application. The "seriously unequal" pipes connect to the exhaust housing after the turbine.

 

It looks decent to me. I wish people would get off this equal length kick. The difference between the OEM manifold and ANY type turbo header is substantial. If you were designing an all out max power engine where 100% of every exhaust pulse is needed to achieve your power curve goals then yes, equal length is beneficial. Assuming the welds are good and the flanges seal, the big problem with this twin turbo header will be getting all the plumbing to fit. A/C is out for sure.

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084.jpg

 

Main concern circled in yellow, that's nearly twice as long as several others. I provided an easy solution, simply copy the other grouping and use two of that style for the manifold. Btw, that's not the equivalent of a downpipe in any way shape or form, that's for the wastegate. Down pipes come off of the back of the turbos;-)

 

Also, I disagree with your statement jgkurz, most turbo manifolds I've seen (Toyota motors, still I6s) have nearly equal length runners.

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It looks decent to me. I wish people would get off this equal length kick. The difference between the OEM manifold and ANY type turbo header is substantial. If you were designing an all out max power engine where 100% of every exhaust pulse is needed to achieve your power curve goals then yes, equal length is beneficial. Assuming the welds are good and the flanges seal, the big problem with this twin turbo header will be getting all the plumbing to fit. A/C is out for sure.

 

THANK YOU!!!!!!!!!!

 

Far too many people believe that equal length maximizes power potential of an engine.

 

It can when the length is a matched length for the diameter to the RPM range that max power is being made of the actual engine the header is mounted on. That power band also becomes narrow.

 

On a street car, unequal length headers are more desairable.

The power band becomes wider, and at the cost of usually only a few HP, literally, like 5 or 10 HP in most applications it seems.

 

If you just arbitrarily make a header a random equal length, the tuning of that length may not match the power/torque peak of the engine it's bolted to and can make overall performance suffer, or at least not have the full potential that the builder believes it has.

 

In short, forget about headers needing to be equal length on anything other than a max effort, pull all power you can possibly sqeeze build, where you'll end up making several sets of headers and dynoing each set to find the best match. For 99% of people that build a car to drive, this will not be the case and the non-equal length headers would likely perform as well, or better than some equal length headers.

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Guest 280ZForce
anyone notice the FLANGE is cut in two pieces?!

 

I can understand to prevent the manifold from warping due to uneven heating..

 

But damn.. one bolt to hold TWO exhaust runners on a flange and prevent leaking or a torn gasket?!

Actually the flange is 3 pieces, not 2! lol and NOT 1 bolt for each side, think bout it... there are 4 bolts to hold the outside runners on each side and then there are 3 bolts to hold the inside runners. Still takes 11 bolts just like a normal flange.

 

Now the crazy part is that the turbos mount under and the wastegate portion is the top of it. So I'm guessing depending on the size of w/g they use, it could and might very well be sticking out of the hood.

 

And yes, equal length header(s) are not extremely important in a street app. as mentioned, heck they are pretty close anyway and have to be routed like to that allow ample room for the 1st down pipe to squeeze in and possibly dodge the shock tower or steering rod? Also being tubular and routed nicely makes it way better than stock already. I'd say it's a pretty decent piece as long as the welds are good and it can handle the heat expansion/flexing.

 

This is how it should look rotated properly and bolt holes outlined and #'d also, the yellow to show where the flange is separated...

 

086a.jpg

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Twin turbo this and twin turbo that. TOTAL waste of money and time. That setup will not get you any more power then a single turbo will. But what you do get is double the cost of the turbo's. A PITA exhaust system that will only frustrate you getting it to work correctly. To pull more power you will have to do all of the head work and all that jazz, but some people like to do things the hard way just for the bragging rights.

I run a GT35R turbo, I get full boost (26psi) @ 3200 rpm. The car ran 658Hp @ 22psi of boost, and at the time, having completed 15 pulls or so the engine did not make any more power @ 26psi. But the engine intercooler and everything was running about 60-62 degrees C on the intake charge. As soon as I had it on the road, the temps went to 40 degrees C and the car was running lean at the top for a short rpm range.

So do you, or would you want to go that route, I sure would not want to.

anyway.

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Justin I meant to say the flange is cut in two *places*.. which would mean 3 total pieces.

 

 

The "washers" from the intake manifold to hold the flange down just worries me .. if not torqued to spec or the bolts become loose at all.. the flange will shift all over under the washer.

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I love how the people invested in a big single always bag out twins. Sounds like a case to me of: if I've got it, its the best.

 

That being said, the biggest (only?) potential benefit offered by a twin turbo setup, as I understand it anyway, involves interaction of the exhaust pulses. You only have three pulses joining together in a collector, so immediately you have less opportunity for reversion in non-firing runners.

 

The cons are well known:

- extra weight

- extra cost

- extra complexity

- less room to work

 

Of course, you can make a turbo manifold with two collectors, one for each set of three cylinders, that ends in a divided pulse flange. Which is what I was lucky enough to score.

 

Did I mention the syndrome that whatever you have is automatically the best? ;)

 

Dave

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