Volumetric Efficiency
Volumetric Efficiency
(OP)
How do I find my engines volumetric efficiency?
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RE: Volumetric Efficiency
Is that what you meant?
Cheers
Greg Locock
RE: Volumetric Efficiency
RE: Volumetric Efficiency
Next you need an accurate method of measuring AFR.
It's a relatively easy task to work out what your VE is once you have determined the airflow into the engine ( AFR X Fuel flow)- I won't go into it here as I don't think that is what you were asking.
I wouldn't trust the Oxygen sensors - used in emissions exahust equipment for consistent enough AFR reading to give good VE. The reason being - that when the mixture is very rich- there isn't much oxygen in the exhaust anyway- thus leading to its inaccuracy.It is far better to use emissions analyser kit getting a reading of H and C in the exhaust and using the spindt method to determine the AFR.
A standard MAF sensor has alot of signal drift and usually can't decipher between forward and reverse flow ( can lead to signal aliusing errors)- but usually gives a good inidication of the SHAPE of VE curve.
If you need to find out the VE of a particular road car, you could try using a MAF sensor and calibrating it to a steady state flow rate using a flow bench and then using it to determine the airflow into the engine. Try and mount it at a place on the engine where there isn't alot of pulsing flow/tuning-such as next to or within a large volume. Injector pulse width could also be used, but both of these methods are likely to lead to alot of inaccuracies and errors.
Some manufacturers, such as Porsche advertise/display the WOT BSFC of their cars in their owners manuals, I've often used these figures ( after checking them for consistency) to work back to VE, using reasonable AFRs.
RE: Volumetric Efficiency
Alright let me talk about my own application.
Its hondas new 2.4liter engine (K24a1) From a honda SUV to my 1994 honda civic (With special mount kit). The engine is being completely rebuilt (87mm bore x 99mm stroke) <-Stock.
This engine comes with a Map sensor. (Like most honda engines do.)
An Aftermarket ECU will be used as well as a UEGO sytem. I decided that I am going to turbocharge the 2.4liter, so I called Innovative Turbos, a very very good turbo comp.
As I'm filling out the application for selecting the proper turbocharger I come across : engines volumetric efficiency?
Ok guys I am very new to this V.E. please fully elaborate and ask many any thing about my setup....
Thanks http://www.eng-tips.com
RE: Volumetric Efficiency
RE: Volumetric Efficiency
RE: Volumetric Efficiency
This might not be the "Official Definition", but it is what is meant by volumetric efficiency when you consider that supercharging dramatically increases VE.
Regards
pat pprimmer@acay.com.au
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RE: Volumetric Efficiency
Pat is correct. Breaking it down even further, it is: Ratio of the amount or air getting into the engine’s cylinders vs the amount that will fit. Basically, how efficient is an engine at filling its cylinders, that’s all..
-Joest
RE: Volumetric Efficiency
This guy goes through the calculations in laborious detail (I haven't checked it)
http://www.installuniversity.com/install_university/installu_articles/volumetric_efficiency/ve_computation_9.012000.htm
Here's a study showing VEs of up to 100% http://naca.larc.nasa.gov/reports/1944/naca-tn-935
Cheers
Greg Locock
RE: Volumetric Efficiency
And when it is running engineers try to accomplish that same total volume filling using intake and exhaust tuning and cam timing. Also like others have mentioned using a pump of some sort to help pack more air into the cylinder.
RE: Volumetric Efficiency
Advanced Engine Technology - Heinz Heisler
Forced Induction Performance - A. Graham Bell
Maximum Boost - Corky Bell
The Corky Bell book is a very simple one and a good introduction to the concepts of how and engine works, specifically in a forced induction scenario. Don't take any of the formulas in the book to the bank though, they are often oversimplified to the point of being inaccurate. They often switch back and forth between measurements of volume (which as pat mentioned, is quite meaningless) and mass, They fail to differentiate he two, and convert one to the other without even making mention of STP. This is true in the Graham Bell book too, but to a much lesser extent.
Happy reading :)