camshafts

[NoHachi]

VE is volumetric efficiency: aka the % of the cylinders displacement that the engine actually manages to inhale. Usually this is less then 100% because of pumping losses in the system. Using clever design and harmonic tuning of all runners, racing engines sometime exceed 100%VE. For engines with a form of forced induction 100+% VE is normal.

A normal way of plotting a VE graph would be running the engine of another engine (in fact using it as a pump) and measuring the amount of air going through the system at all rpms...nobody does this though..

Another method is making a graph of dutycycle vs RPM while keeping the lambda constant at one. You then know the mixture and the amount of fuel injected. A crude VE graph can be calculated from this information.

A VE graph is THE single most informative piece of information you can have on a engine. It is THE way to determine a stable idle point for a wild cammed engine. It is also an enourmous informative tool to determine where exactly you place the RPM/Map intercepts (sampling grid) to prevent wrong mixtures through interpolating errors in the ECU.

You get a nice look into the working of the engine, you see every peak in VE where the runners are harmonically increasing the VE..pretty neat. Especially when combined with a computer simulation. you can then make predictions of the locations of peeks and vallies in advance. usually thats enough to determine which peeks are exhaust related and which come from the intake. These can then be worked so that they take place at the same point (=max VE).