Supercharger Secrets: Snowmobile Twin Screw Upgrade

The screw supercharger is a type of supercharger that can be used to boost the performance of a snowmobile. It is a positive displacement twin-screw design that offers superior performance, increased efficiency, and improved durability compared to other superchargers. When it comes to snowmobiles, there are various options for supercharging, including turbocharging and nitrous oxide (NOS) systems. While turbochargers are more common, screw superchargers offer distinct advantages such as higher efficiency, resulting in more power across the entire rpm range. This makes screw superchargers an attractive option for those seeking to enhance the performance of their snowmobiles.

Supercharger kits for snowmobiles

Superchargers are devices that increase the power output of an engine, and there are a variety of ways to implement them. They can be powered by a belt or chain drive from the engine's crankshaft, or they can be driven by exhaust gases, which is the case for turbos. While turbos have become more popular over the past decade, superchargers offer some advantages such as no lag time and the ability to provide bottom-end grunt with arm-stretching torque. This makes them particularly attractive for snowmobilers seeking a boost in power without the drawbacks of a heavier, more costly, and less efficient larger engine.

Speedwerx, a family-owned-and-operated business based in Forest Lake, Minnesota, is a leader in the field of snowmobile supercharger kits. With 20 years of experience, they were the first company to successfully develop a strong and consistent two-stroke supercharger for snowmobiles. Their kits are designed to be simple, reliable, and easy to use, with no need for additional expenses or modifications to the fuel system, clutching, or intercooler. Speedwerx offers two base packages: low elevation and high elevation, each priced at $7,500. Their superchargers have been praised for their throttle response, grunt, and torque, providing riders with confidence in the machine's performance.

While superchargers offer benefits, there are also some challenges to consider. One of the main obstacles is finding a supercharger small enough to fit a snowmobile, as they tend to be bulkier than turbos. Additionally, devising a pulley or gear system to drive the supercharger can be complex. Superchargers also rob horsepower because they use viable horsepower to spin, and they may not be as efficient as turbos due to air/fuel charge loss through the exhaust port. Nevertheless, superchargers present an appealing option for those seeking enhanced power and performance for their snowmobiles.

When it comes to supercharger kits for snowmobiles, Speedwerx stands out as a trusted and innovative brand. Their bolt-on kits offer a straightforward path to upgrading snowmobile performance, and their experience in the field has led to successful two-stroke supercharger implementations. While there are technical considerations and challenges to keep in mind, superchargers present an attractive option for riders seeking more power and a competitive edge on the snow.

Superchargers vs turbos

Superchargers and turbochargers are both air compressors that serve as a "replacement for displacement" by helping to force more air into an engine, providing more oxygen to burn fuel. This allows smaller engines to produce more power.

A supercharger is an air compressor driven by the crankshaft of an engine, usually connected with a belt. It has no lag and provides an instant power boost. However, it is less efficient than a turbocharger as it uses the engine's own power to run, which affects fuel efficiency.

A turbocharger, on the other hand, is an air compressor driven by a turbine in the exhaust stream. It takes advantage of the "free" energy in the form of heat and velocity of exhaust gases. While it provides a significant increase in horsepower, it suffers from "turbo lag" due to the time it takes for the exhaust pressure to build up and spin the turbine.

Both superchargers and turbochargers have their advantages and disadvantages. Superchargers are a cost-effective way to boost horsepower and provide good power at low RPMs. In contrast, turbochargers offer better fuel economy and efficiency by utilising waste energy. They also allow for smaller engine displacements, resulting in reduced fuel consumption during idling and improved overall engine efficiency.

In the context of snowmobiles, some users have noted that superchargers are not commonly used on 2-stroke engines due to the challenge of preventing the air/fuel charge from exiting through the exhaust port. This results in reduced efficiency and fuel economy. Turbochargers, on the other hand, create the necessary back pressure to mitigate this issue. As a result, turbochargers are more commonly employed in snowmobiles, with several manufacturers offering turbocharged options.

Supercharger efficiency

The efficiency of a supercharger is a key performance parameter. The SAE J1723 test standard is used to evaluate supercharger efficiency. The standard specifies the testing process, including the necessary laboratory equipment, test measurements, accuracy, installation of the test article(s), test conditions, and presentation of the results. The efficiency of a supercharger is determined by comparing its performance to an ideal compression process, with the "gold standard" being a 100% efficient, isentropic or ideal compression process. The efficiency of a supercharger is calculated as the ratio of the actual compression achieved by the supercharger to the ideal compression.

The design of a supercharger, which draws its power from the engine, can hurt efficiency by increasing the engine's load. This typically results in lower fuel economy averages. Superchargers work best with large, already powerful engines, which further reduces fuel economy.

A supercharger is always spinning and putting in more fuel and air, whereas a turbocharger only works above a certain engine speed, so it is possible to cruise with the efficiency of a smaller engine and then have the performance of a more powerful one when desired. Thus, when comparing a turbocharger vs. a supercharger, you are more likely to find a fuel-efficient vehicle powered by a turbocharger.

Supercharger displacement

Superchargers are a form of forced induction that compresses intake gas, forcing more air into the engine to produce more power. There are two main types of superchargers: positive displacement and dynamic superchargers. Positive displacement superchargers deliver a constant level of boost pressure at all engine speeds, while dynamic superchargers cause the boost pressure to increase with engine speed.

Positive displacement superchargers deliver a nearly fixed volume of air per revolution of the compressor. The most common type is the Roots-type supercharger, which uses two rotors to capture air and pass it into the intake manifold. Other types include rotary-screw, sliding vane, and scroll-type superchargers.

Rotary-screw superchargers, also known as twin-screw or Lysholm-style superchargers, are similar to Roots blowers but differ in their internal design. They feature male and female rotors with different lobe counts, usually three lobes on the male rotor and five on the female. The rotors turn towards each other, compressing and pressurising the air inside the case. This design makes them true compressors, as they deliver high-pressure air into the intake manifold.

Twin-screw superchargers are more efficient than Roots blowers, especially at higher boost levels. They are capable of achieving efficiencies of up to 70-85%, compared to 40-50% for Roots blowers. This higher efficiency is due to their ability to reduce turbulence and friction within the case.

When considering supercharger displacement, it is important to match the supercharger to the airflow demands of the engine. The supercharger should be sized to deliver the right amount of air to achieve the desired boost levels. This involves taking into account factors such as engine specifications, cylinder head design, compression ratio, and the intended driving style.

In the context of snowmobiles, there have been discussions about supercharging 2-stroke engines. While it is technically possible, some challenges include finding a supercharger small enough to fit and devising a pulley or gear system to drive it. Additionally, the efficiency of the supercharger becomes crucial, as you want to maximise power gains while minimising fuel consumption.

Supercharger installation

Installing a supercharger is a process that can be done efficiently by following a few simple steps. While the installation is not necessarily complicated, the components may require some force to fit together.

Firstly, ensure that all hoses and parts are clean and free of debris before attaching them to your new supercharger. This is an important step to prevent any contamination.

For the next step, you will need to install the oil drain hose onto the drain fitting, securing it with a hose clamp. Then, place the supercharger onto the vehicle, ensuring the oil drain line is pointing downwards. Get underneath the vehicle and attach the oil line to the drain in the oil pan.

The following steps involve attaching the idler assembly to the supercharger with bolts, using a wrench to secure them. You will then need to push the intake elbow onto the supercharger, which may require some force, and a mallet can be used to help with this.

Next, insert the black elbow so that it goes from the fender to the inlet, and cut a hole for the air temperature sensor with a drill bit before installing the back elbow, placing the sensor near the outer part of the elbow bend. Attach the elbow to the tube connected to the airflow meter.

Finally, place hose clamps onto the end of the inlet tube, allowing you to slip on the blue rubber hose that will connect the inlet tube and the back elbow.

Most superchargers come as a kit with essential hoses, and some, such as the Speedwerx ProCharger Supercharger Kit, are designed as a complete bolt-on kit with everything you need for a premium setup.

Frequently asked questions