A Weber is an Italian designed and made carburetor. Webers were used for years on high performance cars such as classic BMWs, Porsches and Ferraris. These are a great upgrade for classic performance cars.
Weber Design
A carburetor is installed in the intake side of an engine and is responsible for mixing the air and fuel before delivering it to the motor, where the two are mixed with spark to ignite the enging. There are two primary Weber carburetor designs, downdraft (mounted on top of the engine) and sidedraft (mounted on the side of the engine). The best type to use depends on the engine on which the carburetor is being installed.
Power Upgrade
How much horsepower a Weber provides depends entirely on the type of engine it is being used on and state of the tune of that engine. For example, a single Weber used on a stock four-cylinder engine will not produce as much power as three Webers installed on a modified straight-6 engine. Typically, Weber carburetors can add from 5 percent to 20 percent more horsepower.
Considerations
While installing a larger Weber carburetor on an engine may give an instant horsepower boost, for the carburetor to work to its maximum efficiency, the other components should be upgraded as well. A larger performance carburetor works by delivering more air and fuel to the engine, which should be matched with a more efficient intake manifold, exhaust and ignition system.