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Ben26 last won the day on May 3 2018

Ben26 had the most liked content!

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    R32 GTR
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  1. Ok yea, Im not sure on the entry and exit effects so I don't know how that would impact flow in a manifold. Yep that makes sense what you are saying, thanks for explaining!
  2. I am considering the whole system. I understand what you are saying and I do not think that in the circumstance of an exhaust manifold, halving the length would double the flow rate, because the other variables in the equation of fluid flow are also changing. My point was that length does have an impact on fluid flow, and that if all else stays that same, there is an inverse relationship. Yep I have done a little CFD and understand what you are saying!
  3. Hey gtsboy. Im not talking about resistance, only what the hagen-poiseuille equation says regarding flow rate and length of a pipe. Of course I was assuming all else is remaing constant, as I previously mentioned, so if there are other variables in the formula changing than that would affect the relationship between flow rate and length of the pipe. Hmm thats an interesting example but something that to me cant be quantified without measurement in my mind. Awesome that we can have this discussion!
  4. If the pressure differential was 0, wouldn't that also mean the flow rate is 0? That's what that equation says. I'm happy to be wrong and learn something new, but going by that equation and researching pipe flow vs length, thats what im reading!
  5. I disagree mate, if you rearrange for Q . Ie they are inversely proportional if all else stays the same. Maybe I'm missing something but I just typed pipe length vs flow rate into google and this was the answer as well "Flow rate varies inversely to length, so if you double the length of the pipe while keeping the diameter constant, you'll get roughly half as much water through it per unit of time at constant pressure and temperature."
  6. This is the hagen-poiseuille equation. Am I interpreting wrong?
  7. I don't think there would be a benefit from lower flow rate, although im not sure. However lengthening the runners may have a benefit via timing exhaust pulses and scavenging? That is the trouble most of the time right, we try different modifications but dont always have the time or money to do direct back to back comparisons! It doesn't work comparing different cars with different setup, because there are far to many variables. Ah well, hopefully one day someone will on here and post the results for all to see!
  8. Yep, understood and agreed with both of you, diameter of the runners has more influence on the pipe velocity, however flow rate varies dramatically with length of the pipe. Half the length of a pipe and expect double the flow rate. All very interesting, now who has the budget and time to test all of this with different length runners and pipe diameters on the same turbo setup and see what happens!
  9. Well the velocity of gas coming out of the manifold drives the turbine right, so you would think different velocities of air would have a different effect on the turbine in my mind? Yea im not going to pretend that some modifications I make are for aesthetics or sound haha. Most are functional but hey the whole experience is not just about perfection otherwise we wouldn't own skylines!
  10. Yea ok, interesting. Agreed, trialling a few different length runner designs and thicknesses with the same turbo setup would make an interesting comparison.
  11. Yes me too, its great learning from other people experiences and trying to put together your own understanding to then test in practise. Ok, that definitely makes sense, but I wonder if the runner length determines the optimum speed the turbine will operate at, ie alter where the turbo chargers are at peak efficiency, and therefore tune the runners length depending on turbine size, rpm limits, cam sizes and boost pressure. This is something I would like to play with. It makes sense what you are saying based on how a turbocharger works, and definitely when your only collecting three cylinders per turbocharger as opposed to 6 with a single turbo manifold. A somewhat important part of the runner length / shape to me is also sound however, and I have found that the longer the runners, the more I like the sound. Maybe not something everyone cares about.
  12. Interesting, what did you find Lithium / what are your thoughts on twin tubular manifolds? I recognise that modern singles with an equal length manifold will likely out perform 99% of twin setups, however I love the idea of twin manifolds for the racing nostalgia to group a etc
  13. Hey Mat, Did you ever get a video or up the boost / make any more changes? Cheers, Ben
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