Calculate the volumetric efficiency of your engine with this calculator.
Enter your data, get the result. Simple!
What information does the VE calculator need?
- Engine capacity in CC (cubic centimeters)
- Engine power in bhp
- RPM of peak power
What is volumetric efficiency?
In simple terms, volumetric efficiency is how filled the cylinder is, (immediately before the compression stroke starts), compared to the actual capacity of the cylinder.
In other words, how easy is it for the air to enter the engine. The better the VE the more power the engine has.
Generic VE Examples
A normally aspirated engine which is designed for torque will have a low VE at high RPM because cylinder filling at low RPM is the priority
A turbo engine can have a VE of over 100% because air is being forced into the engine under pressure by the turbo ie the amount of air in the engine is more than the actual capacity of the cylinder because the air is pressurized above atmospheric pressure (by the turbo)
Actual VE Examples
Looking at the engine power output data of some vehicles and using the VE calculator above, let’s calculate the VE of the cars below and lets look at what power the engine could make if we change the RPM at which the engine has peak VE.
Honda S2000, 2004 – Normally Aspirated (Non Turbo)
Nissan Micra 1.2, 2009 – Normally Aspirated (Non Turbo)
Ford Focus ST, 2014 – Turbo
Honda S2000, 2004: 237bhp at 8,300 rpm = 99% VE
Nissan Micra 1.2, 2009: 79bhp at 4000rpm = 110% VE
Ford Focus ST, 2014: 286bhp @ 5500 rpm = 180% VE
With the Honda, not a lot we can do because the peak VE is close to redline.
The engine, even though it is normally aspirated, is making of 100% VE. Let’s pretend the engine makes 110% VE at 6000 RPM, how much power would the engine make?
Bolting the numbers into the VE calculator we get
115bhp, an increase of 36bhp or 45%. How can we increase the VE at 6000rpm?
Ford Focus ST
Redline on this engine is only 6500rpm
What power would the car make if we move peak VE from 5500rpm to 6500rpm?
338bhp, an increase of 52bhp (18%).
How can we move the VE up?
The car has a turbo from the factory so increasing the boost at 6500rpm would be the easiest solution.