I posted this in the Daewoo build thread but I thought it was neat enough to warrant its own thread.
Today me and the kids took measurements of the engine bay and built prototype models out of cardboard. We'll check to make sure our models fit during the next meeting. We also looked at the stock manifold (I've bought two extras to chop up and use as the bases for our competing designs) and decided how to improve upon it. Honestly, improvement shouldn't be that big of a challenge. The 180 degree, sharp radius turn can't be good for flow and the runner length of 790 mm is clearly biased towards low end torque.
You can see just how huge the OEM part is by looking at it attached to the engine.
The middle school kids came up with something pretty conventional for their design. Basically they shot for small size and good flow. If I had to bet, I would assume this design actually ends up dynoing better, although I think it's going to end up killing low end torque. You can see the pictures below, but they essentially made a triangular box that is biggest near the TB and tapers towards the number 4 cylinder. This design is only 10 cm thick and will probably cut the weight of the stock manifold by 60%. Just looking at it compared to the old one, I'm guessing this manifold will be considerably more high rpm intensive.
The highschool kids, on the other hand, came up with something really trick. I hope this works better because if it does, it could be such a neat proof of concept.
As for the aforementioned concept, the idea is to build a reasonably compact manifold with short runners that still maintains good mid range power and a flat torque curve. The high school kids are trying to do this by separating the airflow from the reversion waves as much as possible. In theory, the airflow moves largely undisturbed from the very low mounted (close to the flat floor of the plenum) TB and then under the triangular cutouts, but each triangular cutout is designed to reflect the reversion waves at a 90 degree angle and off a flat surface before bouncing them straight back down to the runner. This effectively lengthens the duration of the reversion wave heading back to the intake valve with only a tiny increase in the size of the plenum and no increase in the length of the runner. I was playing with some ideas and think I might take this concept further by trying echo chambers of varying sizes attached to the vertical faces of each triangle. If the concept works, it should be a simple matter to make the manifold more low RPM biased by increasing the size of the echo chamber.
The students then decided to flatten the torque curve by staggering the distances of the reversion wave reflectors (what I'm calling those triangles). This should result in each cylinder having a slightly different torque curve. Since it has the longest distance between the intake valve and a reversion surface, cylinder one should make the best low end torque. Cylinder four should make the best high rpm power.
Like I said, I've never seen anything like this and I'm not sure if it will work, but the idea is so creative and interesting I'm really rooting for it.
