347 Short Block Fast Ford Formula Part 2
Boost Curves-Stk vs. RHS/XFI/RPM II
It is true that the boost pressure supplied to both combinations by the Vortech supercharger peaked at 8 psi, but that doesn't mean the boost was the same. The difference was that the peak reading was taken at 5,700 rpm for the stock components and at 6,300 rpm on the modified motor. It typical fashion, improving the airflow and power output of the normally aspirated combination by upgrading the heads, cam and intake resulted in a drop in boost pressure. This is not surprising since boost can be thought of as back pressure. The more restrictive the motor, the greater the boost or back pressure. Applying the supercharger to the stock combination resulted in 8 psi at just 5,700 rpm, where the modified motor did not reach 8 psi until 6,300 rpm (a change in impeller speed of over 3,000 rpm). More power with less boost is the best of both worlds since it helps further reduce the risk of detonation. View Related Article
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