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Throwaway Technology?

Variable valve systems, sure, but compression?


on says the automobile is the single most recycled consumer product in the US and that almost 100% of automobiles get recycled. The website says salvage vehicles are drained of fluids and all the reusable parts – wheels, windows, trunk lids, hoods, seats, doors, and any mercury switches – and what remains enters the shredder to become chunks of nonferrous metals, steel and non-recyclable plastics, glass, rubber, etc. In the process, steel and iron are magnetically separated and shipped to mills to become new steel. 

My 2017 SUV’s engine features variable valve timing and factory turbocharging; thus, it never embarrasses me when I call for acceleration. Plus, it averages 30 mpg in about-town driving, so, obviously, I have no performance complaints. However, I plan to trade it in within a few years, before the expensive turbo begins to wear. This plan addresses one of my criticisms of modern engines – efficient when new but pricy to later fix or rebuild. It’s an ongoing characteristic that more and more distresses the used car and light truck market, because used vehicle buyers can suffer hardhearted costs by owning and maintaining expensive-to-rebuild cars or light-duty trucks, ones that can’t be repaired in the family garage. Fortunately, present-day turbochargers and variable valve timing systems are proven and well-tested, but upcoming engine designs – such as Nissan’s variable compression ratio engines – offer more efficiency for turbocharged engines, yet include appallingly complex designs. 

Variable valve, ignition, fuel injection, turbocharging, cooling and lubrication systems have become commonplace in modern vehicles, but variable compression has always been seen as a final frontier. No more. Not only is Nissan offering such a system, but other automakers are also exploring variable compression. 

Porsche is developing a top-secret variable compression engine, and Honda, Peugeot and Waulis Motors have patented variable compression designs. Nissan’s now-advertised variable-compression engine is controlled by a harmonic drive system, i.e., a flexible strain-wave gear assembly that provides precise elevation adjustments to the crankshaft system. It’s a well-designed system, albeit expensive and complicated, especially since the components reside in an ungainly protuberance extending from the lower engine block. This variable-compression system is composed of a multilink arrangement, one that comprises a harmonic motor that swing arm links to a fixed-point (fulcrum) bell crank that is linked to the crankshaft (shaft and bearings) and converts the harmonic motor rotation to vertical movement. This action, of course, affects the piston-topped pushrods and subsequent compression ratio. The key component is the harmonic drive that, via software influenced actuators, reacts to driver foot demands. High compression offers extra performance; low compression provides increased torque and a disinclination for piston knock. And both assist the turbo feed system. Still, such a system is cumbersome; it adds complexity, weight, inertia and friction. 


Are today’s performance-seeking engineers designing effective but extravagant machines? No doubt, modern metals and manufacturing methods are excellent and complex engineering may help manufacturers meet government and buyer standards, but, as noted above, such systems can incur higher upkeep costs, especially for buyers of used equipment or vehicles. Thus, if you’re planning on buying a used machine or shop vehicle, your first requirement should be simplicity – rebuildable simplicity. You’ve got to ask: Will long-run maintenance costs exceed the benefits of performance engineering? says advancements in motor vehicle technology hinder the auto parts industry’s expansion. It says per capita disposable income and corporate profits have bolstered demand for auto parts and that favorable car usage trends have led to demand growth in auto parts products, but “advancements in motor vehicle technology have made it increasingly difficult for vehicle owners to repair and maintain vehicles without professional help.” As a result, the site says, many consumers are opting to take their vehicles to auto mechanics instead of purchasing auto parts for do-it-yourself repairs. The website also notes that US auto parts stores employed 386,232 persons in 64,893 stores, with 2017 revenue at $61 billion. The largest chains are Advance Auto Parts, AutoZone Inc., Genuine Parts Co. and O’Reilly Automotive Inc. Of course, we can’t know what percent of their revenues result from sales of actual replacement parts or purchases of monster wheels and air fresheners. 


By the way, are you selling signs to any of the 64,893 auto parts stores?



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