Because more fuel is required to feed a supercharged engine, the fuel-delivery system must be considerably improved. This means large fuel lines of AN-8 or bigger, properly selected and installed fuel pump(s), an adequately designed tank, full flowing filters, and a correctly wired electrical system to operate the fuel pumps.
Blow-Through Carburetion
On a blow-through supercharger system, the carburetor can either reside in a pressurized box or utilize a special carburetor hat. Under boost the false atmosphere (pressure being blown into the carb) requires revamping many of the original carburetor designs to properly supply fuel. A blow-through carburetor generally features sealed caps on the metering blocks, the main well, and the idle well. These carburetors typically feature only annular boosters so that as the signal gets stronger more fuel flows into the engine. As boost is increased by each psi, fuel pressure must too be increased at the same rate. To do this, a special regulator is referenced to boost pressure and raise or lower the regulated fuel pressure, depending on demand.
Turn Back
Reverse-rotation superchargers are generally used in applications where there are fitment issues or on engines designed to spin opposite of most other engines. Fitment issues arise when the area behind the belt driveline is impacted. Examples are 32-valve cylinder heads and exhaust manifolds. In this case the supercharger is mounted in front of the belt line. Consequently, the supercharger must now be rotated in a reverse motion, in which case manufacturers design the inner components of the blower as a mirror image of a standard unit.
Ignition Systems with a Supercharger
On any blown engine, high-performance ignitions are required primarily to provide adequate spark at higher-than-normal engine pressures and speeds. Additionally, it is often a good idea to run spark plugs that are one to two ranges colder than normal. Rule of thumb: the more boost, the colder the plug required.
One of the most important concerns with any supercharger installation is detonation control. This is because under acceleration, detonation can damage the piston ring lands (or other worse yet, damage rod bearings, destroy pistons, or blow head gaskets). A handy device to counteract most detonation problems is an ignition system with a boost-retard control.
Ignition timing is especially critical with a supercharger to not only keep detonation at bay, but also provide good power. For most applications, the distributor should have a centrifugal advance mechanism set up so that the entire advance is in by 2,500 rpm. Typically, 34 degrees should be a safe level of ignition lead to provide close to optimum performance.
Depending on size and design,...
Depending on size and design, centrifugal blowers are capable of significant power increases, and since they're relatively compact (compared to the massive positive-displacement design) they fit under the hood of just about any vehicle.
The amount of observed boost...
The amount of observed boost on a gauge can vary substantially. This photo was taken with the throttle closed. Boost is measured when the throttle is open. If the observed boost comes up on the low end, it may mean the engine breathes very well. Another factor that can contribute to low boost is a restricted air inlet or too small a carburetor.
Since adequate fuel volume...
Since adequate fuel volume and pressure are critical to a supercharged engine, it's a good idea to utilize a fuel pressure gauge.