| already gone through my initial design phase for a new intake manifold that I will soon be building the prototype for and testing, however, I hope that my input may also be taken for its face value of my countless hours of research of the already well-understood physics surrounding how such a part should be designed for a given performance goal. Additionally, the computational modeling that I have employed in my own design has given me further insights into designing an intake manifold for OUR engines that go beyond the scope of the general study. By eliminating the upper plenum entirely there are several fundamental issues. 1) The runner length has been shortened to such an extent that in order to get into hemholtz resonance would require the engine to be spinning over 10,000RPM in order to produce any tunnel-ram effects. 2) Given that our engine's cycle pattern runs straight down from 1 to 6, 120 degrees into cylinder #1's intake stroke, cylinder #2 enters its intake stroke. Having two adjacent intake runners competing for the local air volume is going to compromise both cylinders in terms of how much air mass will be able to flow into them. 3) The volume of the "plenum" chamber in this configuration severely lacks a proper "well" of air content for the runners to draw from. The larger majority of the air content going into each runner will be by way of high velocity flow moving through the throttlebody, through this small chambered plenum space, and then into the runners. Air does not like to move at high velocities and make sharp right-hand turns down into the intake runners, and even less when you have to runners competing for that air. The OEM design which splits the cylinder banks' intake air such that no two adjacent cylinder intake strokes are pulling air from the same plenum volume creates a configuration where there is maximum separation of the competition for intake air. 1,3,5 share one plenum and 2,4,6 share a separate plenum. With the OEM plenum design and its high volume plenums, you may begin to see why going to bigger throttle bodies has shown by quantitative dyno testing that there is no measurable difference. This is because the cylinder's are not sucking air through the throttlebodies at all. The cylinders are pulling the air volume in the runners PLUS the plenum chamber volume and the total combined volume in just those parts alone is larger than the volume of the cylinder itself. In comparison to the flow velocities through the valves and in the runners, the velocity through the plenum is much smaller and once you get back to the throttlebodies, it is, in comparison, like a gently pulsating breeze. The throttlebodies do not have to supply a constant high-volume supply - it is a transient demand like small waves rippling up at the shore of a lake. This single-throttlebody design also presents it's own logistical issues with installation. I'm not sure what the solution is for routing the plumbing into the throttlebody for twin-turbo setups using mechanical fans but from what I can visualize I have a hard time seeing how that is going to work. I'm all for e-fan setups as I have had nothing but success with it but I know that it is not something that everyone wants to be forced into doing. In short, I see a design that, from a performance standpoint, is going to eliminate all of the low/midrange torque benefits that the OEM plenum offers and as flow demand increases into the higher revs, a competition for flow is going to outweigh any benefit one would see even if they were to spin the engine upwards of 10KRPM to "try" and take advantage of tunnel ram..... Just my $.02.
Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the
tailor.
Albert Einstein
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