Calculating VE

[Kastigir]

Is there a formula for calculating the Volumetric Efficiency, of a given engine? Hell, what does Volumetric Efficiency even mean?

[Hatch92]

i donno.

 

 

 

 

 

 

i would like to find a flow chart for factory heads and intakes.

[Pyrorocketeer]

Volumetric efficiency is basically comparing how much air your "air pump" (engine) is actually pumping per 2 revolutions, compared to its total displacement.

 

There isn't really a formula to find out volumetric efficiency, since it has SO many variables/ incalculable items.

 

Its just like a guesstimate, factory engines run like at ~80% tuned up performance engines can get up around ~95%, and all out race motors can get up to and around 110%. Those are all naturally aspirated motors.... of course boosted engines run waaay higher because they are forcing the air in, instead of just relying on air pressure differences.

 

Edit: Hatch, good luck finding those numbers if the factory never released them. If someone has put them on a flow bench, it was for their personal knowledge, and more than likely they aren't sharing it with others without a cost.....

[Hatch92]

Edit: Hatch, good luck finding those numbers if the factory never released them. If someone has put them on a flow bench, it was for their personal knowledge, and more than likely they aren't sharing it with others without a cost.....

 

yea i realized that. however i think i'm gonna get a b-series head from a junk yard just to get a base idea.

[Pyrorocketeer]

to see what, head flow numbers? They don't really mean all that much/ tell the whole story. They don't say much about port velocity, they can just tell you flow at certain lifts, under WOT. Which most engines don't spend all their lives in this range.

[Kastigir]

http://www.ztechz.net/id2.html

Some interesting information here. It's theoretical. Haven't yet found an actual formula.

[Hatch92]

to see what, head flow numbers? They don't really mean all that much/ tell the whole story. They don't say much about port velocity, they can just tell you flow at certain lifts, under WOT. Which most engines don't spend all their lives in this range.

 

 

i would like to find out just so it will help me out a little more later when i start to build the turbo setup using that GT35r

[Pyrorocketeer]

well even then, all you need to be concerned with is exhaust flow. Intake is going to be forced down its throat, regardless of what the port looks like. Honda heads flow pretty damn well from the factroy, and there isn't much that one can do to 'open them up' to be able to flow a little more

[Blown330]

It can be done, roughly, but I would need so much information as far a cam profiles,how the cam is degreed, chamber volume, piston dish volume, bore, stroke, rod length, deck height, compressed gasket thickness, etc. Most of that would go into SCR and DCR calculation and then a VE could be estimated with intended operational range.

 

 

Oh...and that would be just for naturally aspirated. For a turbo I'd need a detailed compressor map, physical specs, and a lot of other stuff. For the record VE's are often calculated AFTER the engine is put together as then it is a simple matter of measuring mass flow across the engine and making adjustments accordingly.

[Pyrorocketeer]

it would be a really rough estimate.... can you calculate in the Helmholtz resonance effect on the intake, exhaust scavenging, and countless other factors that go into an engine, not very easily.

[lceah]

agreed...it's hard to calculate exactly but you can estimate...I used to have an excel and VE was part of it...I don't know where it is now lol

 

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