What is 100% VE?

[Mazda Ebrahimi]

Frank/G.speed wrote:
> 
> Newbie question, what exactly is 100% volumetric efficiency?  Is
> it simply the 100% filling of a cylinder during the compression
> stroke?  - a 400 cc cylinder sucks in 400 cc (in mass?) of A/F?
> How do you measure VE?
> 
> I have this sentence stuck in my mind, I think I read it on this
> list a week or two ago.  "An engine peaks in VE at its torque
> peak."  That's true right?
> 
> --
> Frank M. Lin      | G.speed - Z.Speed Trust HKS DC-Sports Razo/Carmate Soei
> fmlin at ccnet.com   | Web page - http://www.ccnet.com/~fmlin/gspeed.html
> EG2, 2:0x @ Sears | Info sheet - "finger fmlin at ccnet.com > gspeed.info"


VE is the ratio of the dynamic air flow / theoredical static air flow 
for any given operating point.  In your example, you would take the 
400cc displacement * RPM/2 (in case of 4 stroke), and that gives the 
theoredical static air flow.  Then you measure what the actual engine 
air flow is and divide to get VE.  Of course the above calculation is 
only true for wide open throttle condition.  At part throttle, you 
should also multiply by MAP/BAP.  At least that's my understanding.
It is true that peak torque occures at peak VE, unless there is 
something unusual going on, like improper fuel or spark curve, etc.  
Peak VE simply means that the engine is at its most efficient point as 
an air pump.  All you have to do is make sure you burn it!