Originally Posted by
Roadknee
Let's say we want 12.5:1 WOT AFR. Our injectors flow-tested 84 lb/hr at 22 psi. We're running 22 psi and set injector constant to 84. VE table is in good shape with BLM's mostly around 128. VE table values in many of the 90+ MAP cells are maxed out at 99 or 100 (note: this is not necessarily the true VE of the engine, but what we have extrapolated from lower cells with BLM data as what will be necessary to achieve stoich AFR). We set PE AFR to 12.5. We install a wideband and go for a WOT run and our AFR is, say, 13.2 instead of 12.5. We need more fuel. The VE table won't accept higher values. Four options are available to deliver the required fuel to the engine : (1) increase fuel pressure and retune VE tables, (2) decrease injector constant and VE table values by same percentage, (3) decrease target PE AFR to something less than 12.5, and (4) increase cylinder volume and decrease VE table values by the same percentage. What method you use to provide the engine the required fuel is a matter of personal preference.