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Originally Posted by BigVinnie
Actually Scott I looked at your plenum again and there are some problems. I believe what McRusselPant's is trying to tell you is that most air density will feed to cylinder 1. Using a plenum design with a straight through plenum causes starvation to cylinders furthest from cylinder 1, cylinder one when it gets overlap at higher RPM will always take in more air than the furthest cylinder.
In order to maintain a stable more accurate flow pattern the plenum should use a cone shape design not a strait through design. This basically means that air pressure will become more stable as all 4 cylinders attempt overlap at higher RPM. Either go with a cone shape plenum, or use a straight through that is literally three times the size that you already have.
Ivans is a perfect example of a cone shape plenum using more square volume at the begining of the plenum, and less towards the end. This will reduce cylinder 1 from consuming more air at higher RPM during overlap and scavaging.
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Yeah thats it, I'm not a fluid dynamics major so I can't get into the details of whats going on, but RBS14's manifold has broken every "rule" of intake manifolds I've seen.
I know you did it the way you did for spool time but a larger shaped plenum with an angled or shaped tank would be much better.
Boosted motors #4 Gets more? Not on the SR, the SR overfeeds #3... and so does the MR2. with how small his plenum and how the velocity stacks are blocking air / causing turbulence its very unlikely that the #4 is being overfeed and highly likely the #1 is getting alot of air, granted the ITBs may be helping smooth things out.