The aftermarket has really responded to the demand for easy-to-install boosted power at an affordable price. Weiand offers its 142 Roots-style superchargers for a variety of small-block engines. Its units feature a CNC-machined two-lobe rotor design that produces 3 to 6 pounds of boost, but can be adjusted up to 12 pounds just by changing the pulley.
Edelbrock's new E-Force supercharger kit is a positive-displacement draw-through unit that it claims is capable of boosting power to over 500 horsepower when bolted to a 350 small-block with 9.5:1 compression (8 psi). The unit is filled with Eaton internals and comes with everything you need to bolt it to your ride fairly easily.
Centrifugal belt-driven units, like this ProCharger D-1SC unit, don't make the low-rpm power of their Roots-type cousins, but they generally deliver a cooler boost charge, which allows more power to be made before an intercooler becomes necessary. Their design allows them to move more air with less of a heating effect on that charge. As engine rpm increases, so does the amount of boost pumped out. This is one big reason why they are so popular when the goal is strong mid and top end power.
When you move beyond the typical bolt-on, low-boost supercharger, other areas of the car need to be addressed, particularly the heads and the exhaust system. High-flowing heads and an exhaust system capable of expelling all that atmosphere you're pumping into the engine will help get the most out of your supercharger.
This GM HT383 crate engine was fitted with a Vortech S-trim centrifugal blow-through supercharger system. The Vortech added 200 hp and 120 lb-ft of torque on the engine dyno. Typically these systems can produce gains from 30 to 75 percent, depending on boost levels and volumetric efficiency. This blow-through design encases the 4150-type carburetor inside an aluminum enclosure. According to Vortech, "this results in a consistent fuel curve for more power than an ordinary 'bonnet.'" The enclosure also features front and rear -8 AN fuel ports as well as multiple locations for pressure and vacuum connections.
Typically, non-intercooled superchargers putting out 8 pounds of boost operate with intake manifold temps in the area of 115 to 200 degrees above the outside air temperature. Add an intercooler and that can drop to as little as 28 degrees above ambient. Cooler air is denser air, and that equates to more power. Boyle's Gas Law states that the compression of air will always create heat, and heat limits both how much boost can be employed, the density of the air charge, and even how much timing you can run. The intercooler also acts as a passive wastegate, flattening the boost curve at higher rpm and allowing more boost to be dialed in at lower rpm.
Another way to cool the intake charge is through "chemical intercooling," like what's offered by Snow Performance. Its Boost-Cooler water/methanol injection systems help suppress detonation so more power-producing boost and timing can be used. Water, with its high latent heat of vaporization, cools the intake charge and combustion. Methanol cools the charge and combustion, but also acts like an extremely high-octane fuel as well as adding more oxygen to the combustion.
For those who like to kick it old school, Magnuson offers this slick Gen 1 Classic unit. And while the name may say classic, the internals are top-shelf Eaton Gen V components. Unlike Magnuson's other blowers that push air along the axis of the rotors, this unit draws atmosphere down through the carb and into the intake more like a traditional Roots blower.