Turbocharger Compressor Calculations
Stroke to Bore Ratio
This article first presents the basics of turbocharger operation, and then explores some of the current thinking in turbo-supercharger technology as applied to competition engines.
Since the power a piston engine can produce is directly dependent upon the mass of air it can ingest, the purpose of forced induction (turbo-supercharging and supercharging) is to increase the inlet manifold pressure and density so as to make the cylinders ingest a greater mass of air during each intake stroke. A supercharger is an air compressor driven directly by the engine crankshaft, and as such, consumes some of the power produced by the combustion of fuel, thereby increasing BSFC and engine wear for a given amount of produced power.
A turbocharger consists of a single-stage radial-flow ("centrifugal") compressor (air pump), as shown on the left side of Figure 1, which is driven by a single-stage radial-flow turbine, as shown on the right side of Figure 1,