Nerd’s Eye View: LA Auto Show 2015 – The Engines, Electrons, and Extra Bits


There’s a few interesting things to see when looking closely at the turbocharger. First, the compressor wheel is fully machined; the trend is going towards fully machined wheels on all turbochargers as a forged blank can be used for additional strength. A fully machined compressor wheel can also be quieter than a cast wheel. With a cast wheel, the tips of the blades can droop slightly (we’re talking fractions of a millimeter) as the casting is pulled out of the tool as the metal may not have solidified completely. The variation in tip height blade to blade can create unwanted noises. On this compressor wheel, you can see balance cuts (the little craters) in the hub of the wheel. Behind the compressor wheel, that piece of sheet metal under the thrust bearing is an oil deflector which helps prevent oil from the center housing getting into the compressor housing.
Looking inside the plastic intake manifold, you can see the nice radius leading into each intake runner.
This is the new turbo setup on a 2.5L Mazda Skyactiv engine going into the CX-9. The design of the setup is unique in their variation of a variable A/R turbine housing. Yes, there have been other variable A/R turbocharger setups such as on the FC RX-7 and Acura RDX. Long story short, there is a valve which opens and closes a secondary flow path into the turbine housing.
It’s interesting how gasoline technology and diesel technology are converging. This new gasoline turbo engine has an EGR cooler (the shiny brick on the upper right of the black plastic intake manifold) just as turbo diesel engines have had EGR coolers for years. And this gas engine is direct injection similar to how diesel engines have been forever.
This is the optional cup holder for the new Miata. You can see it’s a tight squeeze between the bolsters of the two seats. It’s not an easy reach to use them either. But who cares really? The Miata is made for driving, not sipping a Starbucks latte or a big gulp! For the auto show, it appears JB Weld was used to keep the cup holders from getting stolen.

So there you have it, lots of turbos, electric motors, orange high voltage wires, and batteries. With all these bits trying to share space under the hood, packaging is becoming a bigger challenge for all the engineers. The struggle is real. Expect to see more active aero on cars too as they chase those last little bits of drag reduction. Waste heat recovery systems? Yup, the Dodge Ram has it as an option and now it’s on the Prius too. I expect to see those systems become more common too.

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