Engine Valve Open Time Calculator (vs RPM)
This valve open time calculator tells you how long a valve is open vs RPM
Why use valve open time?
By comparing valve open time and RPM vs engine volumetric efficiency we can see how much time our engine/cylinder head needs to maintain volumetric efficiency.
If our engine makes 90% volumetric efficiency at 4000RPM, but after this we see VE starting to drop off, we may be looking at the flow into the cylinders being insufficient because the valve or valves are no longer open long enough to get all the air we need into the cylinder.
We can use this information to change our camshaft profile or perhaps adjust cam timing. Or perhaps we can increase the boost from our turbo to compensate for reduced time to feed in the air (if our turbo allows it ie the turbo is not at the edge of efficiency).
