...BTW your Bieber avatar is awesome.-Malone
Reading through 'TurboJ's' Jetta thread, you are suggested as the man to talk to.I'm building a motor up based on a 1.6 bottom end, VNT turbo and a 10mm headed pump. Currently I'm thinking of using the original 1.6GTD head (with a little flow work) unless a 1.9 head turns up or do you believe the 1.6head is adequate for 150bhp?I have either a NA 1.9 or NA1.6 inlet manifold and was thinking of using the 1.6 one and building a twin plenum chamber inlet manifold.Do I keep the long runners or shorten them to limit low down torque?Are each plenum volume = 1600cc or greaterAnd the tapered slit between chambers? How big? how tapered and does the taper get narrower nearer the intake pipe connection?I'd really appreciate any help you could offer me with this project or pointing out someone or something (book/internet) that will help.Thanks Regcheeseman
Pretty picture...sadly I've forgotten everything I used to know about flow or FEA.Well, almost everything. Next time you're at a fancy-smancy resturant... one where their idea of ambiance is to remove the ceiling tiles and spray paint everything flat black... have a look at the HVAC while you're waiting for your lobster bisque. If the air distribution pipes are long enough you'll probably find that they are stepped down in diameter gradually as the air is distributed... on purpose to help keep the velocity consistent as the pressure decreases.Makes you wonder a little about how much you actually gain by slapping on a gasser manifold or anything else with "straight pipes"?
The purpose to the dual plenums is to reduce the turbulence going into the second plenum and evenly distribute the air to the individual runners. My imagination tells me that without the diminishing cone compensating for the loss of pressure from the initial air flowing into the second plenum, the result would be added turbulence in the second plenum and unequal pressure to the runners. I also imagine that the plenum being straight and the slit being larger toward the inlet would be highly detrimental as it would allow excess air in at the highest pressure area and very little air in where the pressure would be least and the slit smallest. It would seem to be better, if the initial plenum is a "cylinder" rather than cone, that the slit should be smallest toward the inlet and largest toward the later runners in order to compensate for the pressure loss across the initial plenum. Designing the initial plenum to be an appropriately sized cone would be easier and more effective. I've also been of the opinion that without knowing what the goals were and the design parameters and calculations to achieve those goals one could easily cause very little benefit and possibly cause more harm as good. I suspect that many DIY dual plenum intakes are of the "wing it" design and their effect is questionable. Not to criticize AKI in any way (his efforts are very remarkable) but before I emulated his intake design in any way I'd want to know what calculations he used for the design and how he arrived at using those calculations and so far, despite seeing several people on this board ask, zero info on calculating the size/shape of the plenums/runners has been provided.
You could split the IC piping 4 ways equally and then put a dual plane on each cylinder???