This article is a stub. That means that I'm not finished yet and it is probably just going to trail off in mid-sentence, so don't get your hopes up.
There is a debate that rages in our shop on an almost weekly basis. John and Guy are on one side and I'm usually on the other side. See, while I can make things with my hands when I really need to (well, sometimes), most of the time I'm most comfortable designing in a virtual environment, which allows me a lot of leeway in erasing the board without throwing out raw materials and components or being forced to destroy and re-use said components when iterating through the design process.
John & Guy look at things differently – they really can just build almost anything they put their minds to, and diving in and striking an arc come naturally to them. In this article, we'll discuss how both of those methods went hand in hand for our design of the 2011 Kia Optima / Hyundai Sonata Short Ram Intake.
See, it's just plain easier to design an intake on the car than it is to try to bring the measuring arm down, map the whole thing out, design it in a vacuum, source parts, build out the design and then install it. But the devil is in the details. Our intake features a 3.5″ diameter mandrel bent elbow that transitions smoothly into a 3″ straight and then into a lofted silicone coupler that reduces further to the 2.5″ inlet on the turbocharger. But what we are after is minimal pressure drop and maximum velocity at the turbocharger. We know how much it pulls in terms of CFM, and we know what the rough design looks like. Here's where I come in with technology.
Our goal is again, to determine the optimal location and transition profile for the 3.5″ to 3″ reduction and to experiment with a variety of iterations of these designs to find the best flow characteristics for the job. Our CAD software does this effortlessly. To start with, we lay out the design 'as built' and draw it up in three dimensional space in SolidWorks 2011. SolidWorks is, in my opinion, the best CAD software on the market for automotive design and engineering firms such as ours. It has all of the feature sets we use for the majority of our designs and it also has a number of simple add ons that allow us to qualify our designs as we go.
There is really one option with the intake pipe that can make changes to the velocity of the airstream and optimize the gradual increase of said velocity to get high velocity and good flow all at the same time. The intake transitions from a 3.5″ inlet at the ambient air end to a 2.5″ diameter at the turbo compressor shroud inlet. At the turbocharger end, we are constrained to our existing silicone design of 2.5″ to 3″ lofted 90 degree elbow. We may change this if necessary, but we left it as a constant in this evaluation in order to limit variables. That leaves us with the location of the transition from the 3.5″ mandrel bent intake pipe into 3″ straight.
So lets look at a design that waits to the last minute to create that transition and how it impacts velocity and flow:
Our maximum velocity is 3234 inches per second. Roughly 180 miles per hour at the turbo. Good stuff. But lets look at the conical transition above the silicone coupler. The indicating spheres go from a green (~1600 in/sec) flow from the top all the way to the transition and then rapidly jump to 2200+ in/sec. Not the best transition, easy for this to cause turbulence at throttle tip-in and potentially jumpy behavior.
We also can see the to some extent unavoidable high(er) pressure/velocity zone in the inside radius of the last bend. This is not only due to being at the inside of the bend, but also due to a slight kick up that the air traveling on the outside of the bend has as it gets into the final reduction, It literally curls around and adds a little pressure to the air above it.
Now look over to the right, this design uses a much earlier transition point.
Peak air velocity jumps up a little bit, but the transitional and overall velocity throughout the intake increases markedly. Transition is more gradual, but really that extra air velocity halfway up isn't buying you a whole lot other than ensuring that the transition isn't abrupt.
So we then work that conical transition down ever so slightly and end up with our final design, shown below:
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and that's where I stop writing right now....more to come
-Jason Griffith, Engineering Director. Nameless Performance, Inc.