Procharger vs Roots: The Best Supercharger For Your Build

ProCharger has become a buzzword in performance engineering. But what exactly are they, and how do they compare to traditional Roots or twin-screw superchargers?

In this article, we’ll explore the inner workings of ProCharger centrifugal superchargers and contrast them with positive-displacement designs. We’ll delve into boost delivery characteristics, thermal efficiency, parasitic loads, and how each type shapes an engine’s powerband. In the process, I’ll highlight ProCharger’s innovations (from intercoolers to programmable drives) and discuss practical factors like reliability, tuning, everyday drivability and road legality. The goal is for enthusiasts to have a clear technical understanding of how ProCharger systems stack up against Roots and twin-screw blowers in modern engine tuning.

A ProCharger is a gear-driven centrifugal supercharger, a belt-driven compressor that forces more air into the engine. In appearance and operation, it resembles a turbocharger’s compressor: air enters the centre of an impeller wheel and is flung outward at high velocity, where a diffuser slows it down and converts velocity into pressure. The key difference is that a ProCharger’s impeller is driven by the engine belt, not by the exhaust turbine. This means it delivers boost in direct relation to engine speed. As rpm rises, the impeller spins faster (often through an internal step-up gearset) and boost pressure climbs accordingly. The result is dense, compressed intake air that allows the engine to burn more fuel and make more power.

By contrast, Roots and twin-screw superchargers are positive-displacement designs. They don’t sling air by centrifugal force; instead, they trap and push a fixed volume of air per revolution. A Roots blower uses two meshing lobed rotors to carry air from the intake side to the outlet, effectively pumping air into the manifold. A twin-screw supercharger also pulls air through meshing rotors, but its rotor pair actually compresses the air internally as it moves towards the outlet. In either case, positive displacement units are typically mounted on top of the engine (often in the valley between cylinder banks) and deliver boost almost instantaneously with engine rotation. We’ll dig into how these fundamental differences in mechanism translate to very different boost delivery and performance characteristics.

A twin-screw supercharger sits directly on the intake manifold. Positive-displacement blowers like this give immediate low-RPM boost. Each design dramatically influences the engine’s torque curve and powerband.

One of the most pronounced differences between a centrifugal ProCharger and a Roots/twin-screw supercharger is how they deliver boost across the rev range. A positive displacement blower provides instantaneous boost and a broad torque curve – it starts pushing significant air from low RPM and maintains boost until near redline. This translates to a massive surge of low-end and midrange torque and immediate throttle response, essentially making a smaller engine behave like a much larger one. It’s why many OEMs choose Roots or twin-screw superchargers for muscle cars: the driver gets a dump load of torque right off the bat. For example, a Roots-type unit on a V8 will reach peak boost very early, giving strong pull through most of the rev range and only tailing off at high RPM as efficiency drops.

A centrifugal supercharger like the ProCharger behaves differently – boost rises with engine speed in a roughly exponential manner. At low RPM, the ProCharger’s output is modest; as the engine spins faster, the impeller’s speed (multiplied by internal gearing) increases the boost. This means the peak boost comes at high RPM, producing a power curve that keeps building towards redline. The low-end and midrange torque increase is more mild, often not much above stock until the revs climb.

Essentially, a centrifugal supercharger trades the immediate low-RPM blast for a stronger top-end charge. Enthusiasts often describe it as feeling like a very strong naturally aspirated engine that just keeps gaining power as revs rise, rather than a huge early torque hit. The upside is that, because power comes in more gradually, traction can be easier to manage (hence the adage “spinning isn’t winning”). On a drag car, a centrifugal unit can be advantageous in the latter half of the strip – as the car goes faster, the blower keeps packing in more boost and producing more power. The downside is you won’t get that immediate shove at low revs for instant torque, so in a heavy vehicle or off-the-line launch, a centrifugal might feel comparatively soft until the RPM builds.

To put it succinctly, positive displacement superchargers broaden the powerband starting from down low, while centrifugals concentrate the power increase at the top end. Neither is “better” in absolute terms; it depends on the application. A street-driven 4×4 or a daily driver saloon might benefit from the low-end grunt of a Roots or twin-screw (for towing or quick throttle response), whereas a track-focused car or high-revving build might exploit the high-RPM boost of a ProCharger for greater peak power. Many modern centrifugal kits mitigate low-end lag with clever tuning or even variable drive technology (as we’ll see with ProCharger’s i-1), but the fundamental boost curve difference remains a key factor when comparing these systems.

Another critical comparison point is thermal efficiency – how much heat each supercharger adds to the intake charge and how well they manage that heat. Excessive heat is the enemy of power and reliability in forced induction, as hot air is less dense (reducing power) and can lead to detonation.

Centrifugal superchargers like ProCharger units generally operate with higher adiabatic efficiency than Roots blowers, meaning they impart less heat for a given pressure boost. The centrifugal compression process (like that of a turbo’s compressor) can be quite efficient, often on par with turbochargers. By contrast, a basic Roots supercharger is essentially an air pump, notorious for heating the charge, especially at higher pressure levels.

The Roots design inherently leaks and churns the air, and if it uses tight clearances or seals to improve efficiency, friction can further heat the air. Additionally, being perched on top of the engine exposes Roots superchargers to a lot of engine heat soak.

Twin-screw superchargers improve on this by compressing the air internally (so the air is not solely compressed in the hot engine manifold) and reducing leakage. As a result, twin-screws have better efficiency and lower discharge temperatures than Roots designs. They still sit on top of the engine, but their more effective compression means less heat generated per pound of boost than an equivalent Roots unit.

ProCharger centrifugal systems typically produce a cooler charge for a couple of reasons. First, the centrifugal process is efficient, and the units often spin in open air at the front of the engine bay (away from some of the engine’s heat). Second, ProCharger pioneered the use of intercooling on supercharger kits – something that was once rare on positive-displacement setups. By using an air-to-air intercooler in-line between the blower and the intake, intake temperatures can be reduced dramatically, retaining air density and reducing the risk of engine knock.

Today, it’s common for any high-boost system, Roots or otherwise, to employ an intercooler (air-to-water or air-to-air), but it was ProCharger in the 1990s that made intercoolers standard issue on supercharger systems. The impact on performance was clear: cooler charge air not only increased power output but also improved engine reliability by preventing the heat-related failures (like blown head gaskets) that used to plague supercharged engines running hot intake charges.

Lower charge heat also means the engine can safely run more timing or boost on a given fuel, which is one reason a centrifugal kit with intercooler can often achieve a bit more power on the same boost than a non-intercooled positive displacement setup. Thermal efficiency isn’t just about making power – it also means less strain on the engine in sustained use, a crucial factor for track cars or any hard-driven setup.

All superchargers consume some engine power to drive them. This is the parasitic load or drag imposed by the supercharger. One way to compare systems is how much power they draw for a given boost and flow.

Generally, centrifugal superchargers are more efficient in power consumption than positive displacement types. This is because they gradually build boost and often operate with higher efficiency; they tend to use less of the engine’s horsepower to spin the compressor and produce a given amount of airflow. In practical terms, a ProCharger might rob fewer horsepower at high RPM than a Roots blower making the same peak boost, meaning more net power delivered to the wheels for the same pressure.

Twin-screw superchargers, again, are an improvement over Roots – their internal compression and tighter tolerances mean less energy wasted in heating or leakage, so they typically consume less drive power than an equivalent Roots for the same boost. Yet, any positive displacement unit delivering boost at lower RPM will inherently be drawing engine power at those lower RPM too (even when you may not need full boost), whereas a centrifugal draws significant power mostly at high RPM when it’s making peak boost.

It’s worth noting that turbochargers (driven by exhaust) don’t directly sap crank horsepower, so in terms of parasitic loss, they have an advantage, but turbos introduce exhaust back-pressure instead, so there’s always a trade-off. Among superchargers, the differences aren’t night-and-day – modern kits of all types are generally highly efficient mechanically. In fact, MotorTrend notes that both turbos and superchargers end up delivering similar overall efficiency in adding power, once losses are accounted for. Even so, if one is chasing every last bit of efficiency or trying to minimise impact on engine workload, a centrifugal unit has the edge. Its ability to be placed out front also means you can reduce drive belt lengths or complexity compared to a top-mounted blower, and the smaller size of the head unit might allow better accessory packaging and potentially lighter weight than a bulky Roots manifold.

In everyday driving, the parasitic loss manifests as a slight decrease in base engine efficiency. A Roots or twin-screw blower often has a bypass valve to essentially “freewheel” when you’re off throttle or cruising, minimising drag, so modern units don’t drastically hurt fuel economy when you’re not in boost. A centrifugal has very little drag at low rpm (since it’s not producing much boost then), which can make it feel nearly transparent in light-throttle conditions. From an efficiency and economy standpoint, centrifugal superchargers are quite benign during cruise and draw less power overall per unit of boost, whereas a positive displacement might take a bit more power (especially when producing that big low-end boost) but delivers immediate torque in return.

ProCharger (the brand by Accessible Technologies Inc.) established itself not just by the type of supercharger it makes, but by a series of technical innovations that have influenced the whole aftermarket supercharger industry. Here are some key innovations and features that set ProCharger’s systems apart:

ProCharger was the first to include an air-to-air intercooler as a standard part of a supercharger kit. This was revolutionary in the mid-90s – competitors initially scoffed at the added cost, but the benefits in power and engine safety became undeniable. By cooling the compressed air charge, intercoolers allowed higher boost on pump fuel and greatly reduced the risk of heat-related engine damage (blown head gaskets were a common issue on early supercharged motors without intercooling). Today, almost every serious supercharger kit, whether centrifugal or Roots style, uses some form of charge cooling, thanks largely to ProCharger leading the way.

All ProCharger head units use a self-contained oiling system, meaning the supercharger has its own miniature oil reservoir and pump inside, separate from the engine’s oil. This contrasts with some older designs that tapped into the engine’s oil supply for lubrication. The self-contained approach offers easier installation (no need to plumb oil lines or drill the sump) and keeps any potential debris from a blower gearset failure out of the engine’s oil. ProCharger wasn’t the first to attempt self-contained lube, but they perfected it at a time when not all superchargers had this feature. With advancements in synthetic oils, their units could reliably run in a closed loop of oil, requiring only periodic oil changes for the blower. This innovation has now been widely adopted by others.

Inside a ProCharger is an internal gearbox that multiplies the crankshaft speed to drive the impeller at tremendous RPM. ProCharger pushed the envelope on step-up ratio (around 4:1 ratio in early units), to spin the impeller faster and make more boost. This put greater stress on the gears and necessitated precise machining and robust materials to be reliable. ProCharger’s focus on a high-quality internal gearbox (with minimal backlash and high-speed bearings) was a key to unlocking big horsepower from a compact blower. Over time, competitors copied many of these gearcase advancements. The robust gear drive also means ProChargers can achieve high impeller speeds safely, allowing them to support very high boost levels when needed. Modern ProCharger units continue to use high step-up ratios (along with specifically tailored impeller designs) to achieve efficient boost levels for different applications.

Perhaps the most futuristic innovation from ProCharger is the i-1 system – a centrifugal supercharger with an electronically controlled continuously variable transmission (CVT) between the pulley and impeller. Traditional superchargers have a fixed drive ratio (unless you physically change the pulley size). The i-1 instead uses a rugged dry hybrid CVT and electric motor actuator to dynamically change the drive ratio on the fly. This means the supercharger’s boost curve can be adjusted via a simple control in the cabin, offering modes from mild to wild. For instance, you could dial back to almost no boost for valet or daily commuting, or ramp up to full boost for track use, all without opening the bonnet. The system can increment the ratio in 250 RPM steps, effectively tailoring the boost delivered at each part of the rev range.

These innovations have helped ProCharger stand out and have often set new industry standards. Features like intercoolers and self-contained oiling that were once novel are now commonplace on many kits – a testament to ProCharger’s influence. The continual development (a lot of it driven by motorsport testing) ensures that modern superchargers are more powerful, reliable, and user-friendly than those of decades past.

When comparing supercharger options, it’s not just the performance that matters. Practical ownership factors come into play, especially for street-driven cars. Here we consider how a ProCharger (centrifugal supercharger) stacks up against Roots/twin-screw in terms of reliability, tunability, daily drivability, and legality.

ProCharger units, with their robust billet construction and self-contained oiling, are engineered for longevity. Many users have logged over 100,000 miles with them without issue.

The centrifugal design runs relatively cool (thanks to intercooling) and the internal parts are under less strain at cruise, which contributes to longevity. Positive displacement blowers from quality manufacturers (Eaton, Whipple, etc.) are also very reliable, many of which come as OEM equipment and last for the life of the vehicle. They do, however, put continuous torque load on the engine’s front drive and add heat to the intake, so ensuring proper maintenance (oil changes for their gear-drive oil, belt replacements, etc.) is vital. Overall, ProCharger’s track record in racing and in high-mileage street cars shows that reliability is on par with or better than other supercharger types, provided the system is installed and tuned correctly. As always, pushing any setup beyond its intended boost or speed can cause failures, but in normal operation, these systems are built to last.

In terms of tuning, both centrifugal and Roots/twin-screw setups require careful engine tuning to manage fuel and ignition with boost. Neither is inherently harder to tune, but their different boost characteristics mean different approaches. A Roots blower’s immediate boost might require enrichment and timing pulls even at low RPM, whereas a centrifugal’s gradual boost can be a bit more linear to calibrate. Many ProCharger kits for modern EFI cars come with ready-made tuning programmes for stock engines to get you up and running. However, the best results come from a custom tune by a knowledgeable tuner, especially if the engine has other modifications and uses a high-octane fuel such as E85.

ProChargers are very responsive to pulley changes (to adjust boost), and of course, the i-1 offers on-demand tuning of the boost curve – a unique advantage for ProCharger. Positive displacement blowers can also change pulleys to alter boost, though swapping them in some applications might be a bit more involved if the pulley is hard to reach under the bonnet. Generally, both types are highly tunable, but one should budget for dyno tuning to optimise performance safely. It’s also noteworthy that because ProCharger systems often include intercoolers, they provide a bit more tuning headroom (less heat sensitivity). On the flip side, the immediate torque of a Roots might require tuning strategies to avoid knock at low speed and ensure drivability (manufacturers often include bypass valves to vent boost at light throttle).

How a supercharger behaves in everyday driving is crucial for many enthusiasts. Here, the differences in boost delivery play a role. A positive displacement supercharger feels very integrated with the engine’s natural power – it’s always “there”. This can make a car extremely fun around town, with immediate response and strong torque even with gentle throttle input.

However, it can also mean the car is almost too powerful at low speeds (spinning tyres unintentionally), and fuel economy can suffer if you’re frequently in boost. Modern Roots/twin-screw setups mitigate this with bypass valves so that at cruise, the supercharger is largely inactive (thus not gulping fuel). A ProCharger centrifugal tends to be more mild-mannered at low rpm. When you’re just commuting, you might hardly notice it’s there aside from a characteristic whistle or gear drive noise. The big hit comes in when you rev it out. Some enthusiasts prefer this, as it keeps the car civil in normal driving and saves the fireworks for when you really wind it up.

In terms of noise, a Roots-type often emits a pronounced whine under boost, which many find appealing. Think of the scream of a Shelby GT500 or Hellcat under throttle (Dom Toretto style).

A ProCharger has its own sound; typically a high-pitched whistle at idle and a whoosh of air when the blow-off valve vents, but generally quieter under load than a Roots whine.

From a daily usability perspective, both types can be perfectly street-friendly if well set up. It mostly comes down to whether you want instant low-end power (for towing, hauling, or just the feel) versus a more gradual build. Notably, because ProCharger mounts out front and doesn’t replace the intake manifold, it often fits under stock bonnets and in tight engine bays where a large Roots might not.

There’s also typically less added weight up high on the engine (a Roots blower and liquid intercooler can add significant mass on top of the motor). These can make a difference in handling and maintenance access on a street car.

In regions where emissions compliance and MOT tests are a concern, having a supercharger that is road-legal is important. Many major supercharger kits, including ProCharger’s, are engineered to meet emissions standards. ProCharger actually leads in this area – they offer more 50-state legal (CARB certified) supercharger kits for late-model cars than any other manufacturer. This means you can install a ProCharger kit on, say, a modern Mustang or Camaro and still pass emissions tests (as long as you use the provided tune and configuration that the certification covers).

Positive displacement kits from companies like Edelbrock, Roush, and Magnuson also often have CARB exemptions for specific applications. The legality comes down to whether the kit has been tested and proven not to excessively increase emissions. From an enthusiast’s perspective, if you live in e.g. California or a country with strict inspection, it’s reassuring that ProCharger kits are available with official approval for street use.

Additionally, a centrifugal setup’s ability to run an intercooler can help keep intake temps down, which might aid in staying within emissions limits (cooler air can reduce NOx formation). Noise regulations are usually not an issue with superchargers (they’re not nearly as loud externally as an open exhaust or turbo wastegate). Visually, a centrifugal unit is easier to hide in an engine bay for those worried about the MOT inspector’s gaze, whereas a giant blower atop the engine is quite conspicuous. In any case, always check that the specific supercharger kit you choose has the necessary certifications or exemptions if you intend to use it on public roads. ProCharger’s broad range of street-legal kits is a strong point in its favour for the street enthusiast who needs to stay on the right side of the law.

In conclusion, choosing between a ProCharger (centrifugal) supercharger and a Roots or twin-screw unit ultimately comes down to the application. Technically speaking, ProCharger centrifugal superchargers offer superb efficiency, a linear boost curve that yields explosive top-end power, and a suite of innovative features that enhance performance and reliability. They excel in applications where high-RPM power and cooler charge air are desired. Their progressive boost delivery can make high-horsepower cars more tractable.

On the other hand, Roots and twin-screw superchargers deliver immediate, locomotive-like torque that transforms the character of an engine at low and midrange speeds, pulling harder than any 1.9TDI out there. 

From a technical standpoint, we’ve seen that ProCharger has narrowed many of the gaps of inefficiencies: intercooling and modern design have given centrifugals excellent charge cooling and reliability, while innovations like the i-1 drive even allow their boost to be as accessible or gentle as one could wish. Positive displacement blowers have also improved (modern OEM twin-screws are surprisingly efficient and run cooler than old Roots blowers), but they still impose a bit more parasitic load and heat at high boost levels.

In real-world terms, all these superchargers can reliably add huge performance when installed properly. It’s not a question of one being plainly superior, but rather which best suits the engine’s and driver’s needs.

For a track-focused or high-speed build, a ProCharger’s advantages in efficiency and high-end punch make it a compelling choice. For a street or muscle car build where instantaneous torque is the thrill, a Roots or twin-screw might provide that seat-of-the-pants satisfaction. The good news is that companies like ProCharger have made centrifugal superchargers user-friendly for street enthusiasts (with self-contained oiling, CARB-legal kits, etc.), so you aren’t sacrificing practicality for performance. Likewise, the widespread adoption of intercoolers on positive displacement kits has helped tame their heat disadvantages.

With the information laid out here, a technically minded enthusiast can make an informed decision and appreciate the engineering that goes into harnessing increasing power output with minimal or no compromise. May it be with a centrifugal ProCharger, Roots blower or even a turbocharger. Whatever you choose, there’s no denying the appeal of forced induction’s ability to turn up the power and put a grin on your face.