I want to have a detailed discussion about:
What is volumetric efficiency?
How is maximum efficiency achieved?
How can you achieve more than 100% in an NA application?
What affects does different engine paramenters have on VE?
How is it calculated?
How can this influence the performance of an engine?
+ More....
So engine builders, tech gurus, tuners, everyone chime in... Lets hear your opinions, views and ideas.... I think this is great way for noobs as well as everyone to learn more....

 

Volumetric efficiency is simply the amount of air that actually makes its way into the engine cylinder divided by the theoretical amount of air that can be brought in. For example, if one cylinder can theoretically hold 0.5 L of air but only 0.4 L make it into the cylinder, then your volumetric efficiency is 0.4/0.5 = 0.8 = 80%

As far as getting above 100%, it can be and had been done but it is not easy...

In a naturally aspirated engine, all the standard things that we do to gain power (intake, high flow intake manifold, bigger throttle body...etc) affect the volumetric efficiency of the engine by introducing less restrictions to the air flow. The fewer restrictions the air has to get in, the higher your volmetric efficiency will be.

I could go into a lot more detail, but this should get the ball rolling on this topic pretty well I think...

 

^^^^^^ Great.... Keep them coming guys...

 

pay for some classes and go to school. youll never understand fluid mech. by sitting at an arm chair

 

Yes, I would really like to hear what others have to say about this...We could get into such topics as "choked flow" and pulse waves inside the manifold..The more the marrier.

 

Who really truely understands fluid mechanics anyways??? There is plenty of reading you can go to better understand the volumetric efficiency...

 

I've read in race eng. magazines that F1's are in the 120+% VE range. I'll try to find something to link....

410 WoO SBCs are in the 105 - 110% range.

I'm sure if the airflow research was done, we'd find a lot of the current all-motor K-series cars (and at least one F-series car) over 100% VE.

 

I do recall an article in one of our tuner magazines with a k20/k24 in the 130% range....I tried to find it but had no luck..anyone out there know which one I"m talking about???

 

your talking about the one in the engine masters. Its a memeber heres car actually.

 

Would you happen to have a link to the article? I can't find it...

 

120% VE must be awesome.... I found this in another thread:
VE=(3456 X CFM)/(CID X RPM).... Could anyone verify that this formula is correct???
F1 engines are absolute phenomenums...

 

Check out the ENDYN home page. http://www.theoldone.com There's a k on there that they claim has a VE of 137%

 

I want to know in detailed how can you increase an all motor VE.... Can compression influence VE???

 

You can search a little more also...We have lots of thread and info about this subject here on honda-tech...

 

Yeah theres a few out there, but since this is an actual informational discussion where we can converse and question each other with up to date theory/info, I say we try to keep this thread going. It's not like "Wat siCK CAMS shOUld i gets for my GsR?????" type b.s.

My addition to the thread is that most K20 and F20c motors come cose if not surpass 100% VE Stock. Hell even B-Vtec setup are in the low 90s% stock. Hondas are really technology/research at its best right out of the box. With built race motors forget about it 120-130+ VE is achievable with a big bore, moderately high compression, well-cammed, ported, custom header/intake setups. I will try to comment even more in the future with actual data and resources...

 

VE is good to know and a handy tool for evaluating data but HP/L or HP/ci is a yard-stick I prefer.

 

So let me see if I have a good idea of how VE works. If an engine is say, 1 liter, and has a volumetric efficiency of 120% it would theoretically have the power potential of a 1.2 liter engine operating at 100% VE? Is that the idea?

 

Correct.

 

The name is a little misleading, but VE is actually a mass ratio.

According to Gordon Blair, VE is a ratio of:
1) the total air mass that passes through the intake valves, subtracted by the mass that is pushed back into the port due to reversion
2) the mass that would occupy the swept cylinder volume at atmospheric conditions

In other words: Let's say my 100cc cylinder inducts 150 grams of air during the intake stroke, and of that, 30 grams is lost to reversion. On this particular day, If I had a 100cc container of air sitting in my trunk, it has 100 grams of air. Therefore, my VE (at the current engine speed and throttle position) is 120%.

There are variations of this, such as using the intake air density instead of ambient air density.

 

The most common ways to achieve a VE of over 100% are

Correctly sized INT tract - including ports themselves
Correctly sized EXH tract
High Engine Speed

Its really not that hard to do, and usually the area > 100% is a relatively small window, and this is where you want to do your "racing".

 

By that, do you mean piston speed or rotational speed?

 

also kinda on topic!!!
dont high ve cars produce boost at certion rpms?

i have think it is called interntial supercharging?
im talking they barely go above 0psi?
i know it has to be a hell of motor to do this
im not sure on this just looking to be flamed

 

Honda engines are good. From a Honda SAE paper I read:

H22: 102%
F20c: 112%

 

What do you mean by "produce boost"? Increase manifold pressure above atmospheric?

 

By engine speed, I mean rotational speed yes. Piston speed you would want to keep to a minimum, but that is more to do with friction, but every little bit helps.

And yes, I have seen positive pressure readings on several real good NA setups. You guys would be amazed at the amount of pos. pressure that builds up behind the valve as it shuts on the induction stroke.