Originally Posted by exdos
I don't see how GPS monitoring can give you figures for Volumetric Efficiency, and that's the REAL measure of assessing air-intake mods, especially to monitor ram air-intake systems.
But how can you replicate the ram effect on a static dyno unless you also replicate the movement of air over the car at the commensurate wheel speed? As you've said previously, you would require a wind tunnel to do this on a dyno like the F1 teams use, and this is not feasible. However, there is a very simple and much cheaper way of assessing ram pressure increases, and that is to actually measure the parameters that you need to calculate Volumetric Efficiency using a datalogger connected to the car's ECU whilst driving in "real world" conditions, which aren't just the replication of the environment which creates ram pressure, but IS the very environment in which your car operates. What more could you ask for? My DashDynoSPD cost me about $350, and for that one off payment I can do unlimited dyno runs for evermore, and I also get unlimited access to a free "wind tunnel" as well all the actual data I need to accurately compute Volumetric Efficiency in "real world" on-the-road conditions and a host of other useful data. Why mess around with static dynos?
GPS clearly won't give you volumetric efficiency, but you can extrapolate from the numbers that there is a difference in power can't you? Which is what it all boils down to.
I think there are many more things that can be done to get more accuracy but we are talking about a hundred dollar part here. The dyno is a great place to get an idea. Not to mention tuning is going to be done on the dyno. Most parts are tuned on the dyno, you can't drive around with body panels hanging off, open mufflers, hood opened, etc.