[peterd]

The DESKTOP DYNO calculates the Volumetric Efficency for motor. In my case I have a 408cubic inch small block. You can look at the motor as being an air pump, so in a perfect world this motor would consum 408 cubic inchs of air every 2 revolutions. At 5000 rpm each cylinder could consum 73 cubic ft/min. So DESKTOP DYNO takes into account the flow through the heads, the duration of the cam, the inlet manifold and the exhaust system, all of these items restrict the flow of air and reduce the VE for the motor. I believe the reason some people get bigger numbers than actual is because the motors VE is not reduced significantly by the heads or the cam and the restrictions come from the inlet manifold and exhaust system. Although DESKTOP DYNO allows for a selection of manifolds and exhaust systems the charactistics are not as closely modeled as the heads or the cam. I believe normally aspirated motors producing more than 1.2hp/cubic inch will get high numbers on DESKTOP DYNO.