Transmission Load and Stress Reallocation.
We reconfigured the stresses applied to the high speed bearings, by isolating the “proximal bearing system” (closest to the impeller) so that substantially all thrust force generated by the air end (impeller and volute) is eliminated. This significantly reduces heat generated between the balls and races in this critical proximal bearing set. The reduction of thermal stress on these bearings is so significant, that it allows for a smaller and higher speed rated series of bearings, and more room for other components that many times need relocating.
We developed a Thrust Supporting Distal Bearing System.
The bearing assembly that is farthest away from the impeller is the “distal bearing”. Normally, it is preloaded in the direction that actually compounds the thrust loads that are generated by the air end. Our unique system provides low speed bearing preload, and then additional thrust load is produced with increasing air end boost. This bearing assembly is located in the front cover, as with nearly all centrifugal superchargers worldwide, and is rarely the failure point. But our inventive design has produced the only centrifugal supercharger to actively utilize the distal bearing, as the “high speed thrust bearing”. This is how we virtually eliminate all thrust applied to the proximal bearing assembly, significantly balancing the system loads, and drastically increasing transmission strength.
Our cast volutes are unique and advantaged.
Nearly all centrifugal supercharger and turbocharger volutes are cast with the impeller wall and scroll formed integrally as a single casting. This produces a much less expensive volute but requires metal in locations that can interrupt airflow pathways. Instead, our castings only contain the scroll sections, and the impeller wall section is machined out of billet and installed into the casting. This allows for more uninterrupted flow area, which can lead to more total airflow from a smaller volute in a number of applications. It also allows the vibratory finishing process to get access to the internal air flow sections of the scroll, leaving a smoother airflow surface finish. And the casting has far more uniform wall sections, so the casting process can be streamlined, thus leaving less opportunity for porosity. This process is more costly to manufacture, but allows more flow, primarily when a given volute is nearing its flow limits. Therefore, this can provide greater performance from a smaller volute and less turbulence and heat generally, all with greater efficiency.
We developed a highly Rigid Pinion Shaft System.
There are multiple forces acting on modern high performance centrifugal superchargers. Including rapid gear driven acceleration, with wild reversions in rotating force due to gear changes, tire shake and multiple other factors. Simply producing a larger impeller/pinion shaft will increase rigidity in certain areas but just transfers concentrated stress to others. It can also require less than optimal oversized bearings and can weaken the impeller hub. We diligently worked to develop a unique tapered impeller journal section, eliminating all pins or keyways in the impeller, and also balancing the stresses far more evenly across the entire pinion shaft. We also incorporated several proprietary additional features to the pinion shaft as well. All of these fundamental improvements help lead to far more precise impeller positioning accuracy, and reduces high speed impeller harmonics. Thus allowing for significantly tighter impeller to wall air gap clearance. This greatly improves supercharger efficiency and speed potential.
We eliminated the impeller shim and invented a Virtual Shim™.
Transmissions of all types, for the most part can tolerate a wide range of input or output shaft acceptable final lengths, away from the transmission case. They usually just spline in, support pulleys or gears or have others means. Not as forgiving, centrifugal supercharger transmission length variances, specifically of the impeller shaft, drastically affect the position of the impeller in relation to the volute, and the very critical air gap. So nearly all existing centrifugal superchargers are configured with a specific sized shim, which is placed on the opposing side of the impeller’s retaining bolt or nut. This sized shim is selected, through a series of measurements and calculations during the unit’s assembly process. Unfortunately, this adds assembly time, yields “coarse” air gap adjustments, and a fair number of final assembled units can end up, out of spec with very tight or loose wall clearance. Our inventive system allows each supercharger, with all of its differing component dimensions, to have its air gap set after the entire supercharger is complete, and with no shim at all. A temporary gauge is placed between the impeller and volute. Then an external and very granular adjustment is customized to each supercharger. This allows us to very accurately hold position, which is increasingly critical when the goal is super tight air gap clearance. Again, this increases supercharger efficiency.
All of our superchargers are Internally Lubricated.
Irrespective of boost level or application, this is one of the hallmarks of our Founder’s philosophies. He worked with his former team to develop a highly efficient, supercharger “oil aeration pump”, and then patented it. This invention saturates the critical transmission components at low speeds and start up, but then intentionally cavitates and produces the fine oil mist that all bearing manufactures highly recommend for high speed applications. It operates with a broad range of oil levels, is not sensitive to rapid changes in supercharger motion, never needs to be primed, and requires only fractional horsepower. In addition, engine oil fed superchargers can introduce debris into the high precision supercharger transmission, causing supercharger damage or failure. And, in the event of a supercharger or turbocharger failure, debris will generally drain into an expensive engine and can distribute damaging parts throughout the entire lower end of the engine. This is why all of American Forced Induction superchargers are internally lubricated.
We literally limit our supercharger Transmission’s Loads through Configuration.
As the centrifugal supercharger industry was immature and rapidly developing decades ago, manufacturers were motivated to offer larger and higher flowing impellers and volutes (the air end) as production equipment but integrated with their existing transmissions. Our Founder developed numerous patented transmission improvements, and some other competitors did as well. It has always been significantly easier to produce a larger air end, than a truly stronger supercharger transmission. This is because, as the boost output and air volumes go up, the loads on the transmission go up at an incredibly exponential rate. Doubling the increase in power output from the addition of a centrifugal supercharger can easily multiply the stresses of many internal transmission components by 4-6 factors. So, it’s fairly easy to manufacture a low performance centrifugal supercharger, but effectively impossibly for nearly all manufacturers worldwide to actually produce very large racing superchargers. Since American Forced Induction now produces such high performance supercharger transmissions, but in small configurations, we are putting “racing transmissions” in every supercharger that we produce. And as they are smaller, and more cost effective, we simply limit the air end components for each series that we offer as a manufacturer, that’s all. We change the strength ratio of the transmission in relation to the air end. This strategic approach gives the consumer much greater peace of mind, because we simply limit the transmission’s stress from our factory. And this gives all the more margin for error, and much improved supercharger durability.
We developed a sophisticated, aesthetic and inventive Patent Pending Billet Volute.
As an upgrade on certain supercharger models, all components in our Patent Pending Billet Volute are fully machined from billet aluminum. Traditional castings, especially highly asymmetrical volutes, yield highly misaligned stresses due to the non-uniform casting process. When they are machined, they are relieved of some of these non-uniform stresses and are machined in perfectly round shapes or otherwise. But after machining, they always “spring” back some, so they lose roundness, concentricity, perpendicularity and other important geometry. Billet aluminum alloys are generally formed through forced extrusions, so the grains are far more uniform. This is why billet is such a popular material for super high speed impellers. We believe that our Billet Volutes are the most dimensionally accurate volutes commercially available. They have almost perfectly uniform wall thickness. They are slightly lighter and have smoother air flow paths.
