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<h1>Injector Data - Base pressure</h1> <div class="level1"> <p> Fuel flow rate through an injector is affected by a number of different things. This page focuses on the effects of base fuel pressure and its influence on injector deadtime. </p> </div> <h2>Overview</h2> <div class="level2"> <p> Flow rate through an injector is substantially influenced by the pressure differential across the injector. If we assume that a given injector has been rated at the industry standard of 3-bar (43.5 psi), then the well-known formula for calculating the effect of changing fuel pressure is below. </p> <pre class="code">NewFlowRate = RatedFlowRate * squareroot(NewBasePressure / 43.5) </pre><p> </p> <p> But fuel pressure also affects how quickly the injector can open and close. Higher pressure differential (base pressure) increases the amount of force the injector internals have to overcome to start flowing. This increases the "deadtime" of the injector and needs to be taken into account. </p> </div> <h2>Data</h2> <div class="level2"> <p> To illustrate this affect, we took a set of FIC BM1450s and ran them at varying fuel pressures from 35psi up to 60psi in 5psi increments. The results are shown below. </p> <span class='np_break'> </span> <div class="table"><table class="inline"> <tr class="row0"> <td class="col0"><a href="/wiki/lib/exe/detail.php?id=injdata-pressure&media=pressure-effects.png" class="media" title="pressure-effects.png"><img src="/wiki/lib/exe/fetch.php?w=300&tok=724aec&media=pressure-effects.png" class="media" title="Fuel pressure effect on deadtime" alt="Fuel pressure effect on deadtime" width="300" /></a></td> </tr> <tr class="row1"> <th class="centeralign"> <em> Click to enlarge </em> </th> </tr> </table> <span class='np_break'> </span> </div> <p> Flow rate in that chart above was normalized to 43.5psi to illustrate only the effect on deadtime since the effect on fuel flow rate is easily calculated. If you really want to see the original, unaltered version, <a href="http://www.ecmtuning.com/wiki/_media/pressure-effects-noscale.png" class="urlextern" title="http://www.ecmtuning.com/wiki/_media/pressure-effects-noscale.png" rel="nofollow">click here</a>. </p> <p> Obviously changing base fuel pressure changes deadtime as well as basic flow rate. So both effects need to be taken into account when changing base fuel pressure. </p> </div>