Preparing carburetors for use in a blow-through application typically involves few, if any, modifications. Among those needing no modifications are Holley's HP-series carburetors, which are designed with no choke assembly and are generally equipped with Nitrophyl floats. For standard double-pumper carburetors, the choke assembly should be removed to provide optimal airflow and performance when used with a carburetor bonnet. Additionally, the brass floats--which will collapse under boost--must be replaced with Nitrophyl floats. With only a few modifications and proper jetting, Holley double-pumpers will typically flow enough fuel to support roughly 1 hp per 1 rated cfm of airflow. Single-carburetor applications exceeding 1 hp per 1 rated cfm may require additional modifications such as resizing main wells and power valve restrictions, changing boosters, and emulsion circuit recalibration. Generally when modifications like this are needed, we send people to a reputable blow-through carburetor builder like The Carb Shop.--Cary Pangrac
To maximize power and reliability in a supercharged engine, intercooling is imperative. That's why we include intercoolers as standard equipment in nearly all our blower kits. It helps to understand that no supercharger alone will ever begin to match the system efficiency of an intercooled supercharger system. This is simply because compressing air creates heat, as dictated by the laws of physics in Boyle's Gas Law. Cooling down that air allows for higher boost levels and safer power production. Since intercooling removes heat, increases air/fuel density, and allows the use of factory ignition timing, a well-designed intercooled supercharger system will produce far larger power gains than a non-intercooled supercharger system, especially for fuel-injected motors running pump gas. ProCharger manufactures both air-to-air intercooler systems for street/strip use and air-to-water intercooler systems for racing only. For automotive street applications, air-to-air technology is easy to install, highly effective, and extremely reliable since it has no moving parts and requires no maintenance. Air-to-water intercooler systems, on the other hand, are much more difficult to install because they contain an intercooler, a water tank, a pump, and a separate radiator to cool the water. Probably the biggest drawback to air-to-water intercoolers on the street is that they require ice to match the efficiency of air-to-air units. Additionally, the requirement of ice and the possibility of pump failure or leakage mean that air-to-water is also inherently less reliable. For race-only applications, air-to-water works well since adding ice at the track prior to each run is not hard to do. The other issues are the same as listed above for street applications, and efficiency will be comparable with the use of ice.--Jim Summers
Supercharged motors would run like dogs if blower impellers spun in proportion to engine rpm. Consequently, superchargers employ an internal step-up ratio, which is simply the number of times an impeller rotates for every revolution of the engine. "There's more to achieving a proper step-up ratio than simply shooting for maximum boost," Summers explains. "A proper step-up ratio allows the customer to use a larger diameter drive pulley for better belt wrap and more belt traction. A 4.10:1 step-up ratio is great for street and many strip cars. Our F-3A and F-3R race models have step-up ratios of 6.24:1 and 5.63:1, respectively."