![]() Given that the PK belt is a commonly used item and found in almost all modern applications the belt manufactures a constantly developing new compounds and fibre reinforcements to make these belts stronger, more durable and resistant to slip.Īlmost everyone is familiar with the large tooth belts used on top fuel, alcohol, etc. The most commonly found accessory drive system in modern automotive engine applications is the PK profile serpentine belt. These angular acceleration rates (radian/sec) when combined with the moment of inertia (kg/m2) of the rotating components in the supercharger add a substantial load to the drive system. All adding up to a reduction in slip and increase in belt life.Īdding to this is the maximum acceleration rate of the engine. Not only a reduction in belt load but an increased belt wrap, more contact belt area and a larger wrap radius. A reduction of ~231N in belt load for the same supercharger speed and pressure ratio. The same 100kW 18000 rpm and 53.0Nm of torque now equals ~1284 N the 41.3mm pulley radius. If we were to change the pulley configuration to a 233.6mm crank pulley and an 82.6mm supercharger pulley for the same drive ratio of 2.829 the number work out as below. In the above example with a 70mm supercharger pulley, we require ~1515 N the 35mm radius of the pulley (1515N of belt load) to drive the system. Under a steady state load (no acceleration load)įor example, we are running the combination of a 198mm crank pulley and 70mm supercharger pulley to achieve this supercharged speed an engine RPM of ~6400. Supercharger drive load (kW) is derived from torque (Nm) and Supercharger (RPM)ġ00kw 18000 rpm translates to 53.0Nm of torque It is sometimes better to think about the overall system rather than just running a 65mm or smaller supercharger pulley. Smaller pulleys also = less surface area, higher belt loads, belt slip and reduced belt life. Smaller supercharger pulleys = more supercharger speed = more boost = more happiness Supercharger Pulley Diameter - smaller is not always the best option On the smaller side of the scale - TVS900 18000 rpm – 2.0 pressure ratio requires around 30kw. ![]() On the large side - TVS2650 18000 rpm – 2.0 pressure ratio requires in the region of 100kw.Supercharger drive load, supercharger pulley diameter and engine acceleration rate are a few of the factors that contribute to the direct load applied to the belt. There are many contributing factors to belt load. As the supercharger speed or pressure ratio increases so does the load requirement of the belt, related accessories and idler pulleys. This load is transmitted from the crankshaft through a serpentine belt to the supercharger. Packaging– can you fit an additional belt pathĭrive load– supercharger size, speed, pressure ratioĮxisting accessory belt size – in most cases there is a pre-existing serpentine beltīelt load applied to the crank nose– the further out the more load in the crank noseĪ separate drive system for the supercharger is most commonly thought of as the best solution but due to the constraints listed above it is not always achievable.Īs everyone knows, to turn a supercharger at a given speed and pressure ratio requires input power. This choice has quite a few factors to consider. Combinations of - All on one belt, shared accessory drives and standalone drive systems exist and all have their benefits and shortcomings.īelts - 6PK, 7PK, 8PK, 10PK, 12PK. Below is a snapshot of some of the different drive systems for varying kits. This requires many varied and sometimes complex drive installations. Most modern supercharger systems are crank driven typically with a serpentine style PK section belt. With the ever-increasing variety of supercharger size, drive ratios, belt routing, belt material and pressure ratios we will be taking a look into the design and choice of drive systems, pulleys and belt selection. DESIGN AND CHOICE OF SUPERCHARGER DRIVE SYSTEMS, PULLEYS, BELTS AND TENSIONERS
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