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Originally Posted by AMS
Have you tried different taper angles (on both planes) & what did you find? What camshafts did you use for your timing events and did you find that runner shape/length changed with different intake durations?
I went through a bunch of different variations on the dyno before we settled on our design.
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The timing for the intake events dont matter as far as optimum flow is concerned. The transition from one intake runner to the next is good enough. Even if you have a second valve open while the first one is open it is still the transition that matters (Going from one port to the next). As far as determining peak TQ then yes, the runners matter tremendously.
As far as the taper angles you mean on the plenum side or runner side? The plenum side we have played with alot. The more taper = more pressure = pushes air towards the first intake runner. Obviously less taper = less pressure and helps get the air to the farther runner.
It was also noticed that the more taper you have, the smaller plenum is needed to keep the flow in a controlled state. Considering we dont want a 4 cu/ft plenum it became pretty obvious on the sizing and taper pretty quickly. I was very surprised on the cone -> plenum angle however. I originally thought by placing the cone on the top rearmost part of the plenum and angling it towards the runners would be the best. I was wrong. That led to alot of air getting compressed into the non-active runners.
As far as the taper on the runners I determined that the best would be roughly a 1-2 degree taper. When I squished it much farther than that it started to raise the pressure in the plenum hurting the flow.
As far as the peak TQ numbers and runner length stuff it is kinda in the air. We have an educated guess based on other manifolds we have but dont have any hard data on any of it. The runner lengths shouldnt effect the manifold design at all anyways... it is just tuning the length for the right peak TQ. We will use a few different lengths most likely in the end depending on where people would want thier manifold to push the TQ to. Motors spinning at 10.5k obviously would need a different length then motors spinning to 7k. I think we will end up with two different lengths. One aimed at stroker motors and the other for destroked 2.1s and 2.0s. It also depends on if we go the investment cast way or the weld together way.