" *V/P (Volume/Pressure) Index is a mathematically-derived figure, the product of the corrected volume and cranking pressure. It’s a very useful barometer of the motor’s low-speed power, and may be solved with new variables for a “before & after” analysis when modifications are contemplated. Anyone planning a cam or compression ratio change would definitely want to know how much the low-speed flexibility would be affected. Some useful insight may also be derived as to the motor’s tolerance of pump-quality gas (ping & knock resistance). The results of these comparisons are generally quite surprising!"