how to calculate volumetric efficiency ??

[vnsswithcam]

hi guys just wondering if anyone knows the calculation to get the correct ve? or is there a thread on here you could point me to that outlines what i have to do to calculate it
cheers

[VL400]

If only it was as simple as a formula There are engine sim programs to get it close but you will need to know everything about the engine to get an accurate model.

This is a good website if you a few hours to spend reading how a MAF model can be used to create a VE table .. http://redhardsupra.blogspot.com/

[delcowizzid]

yeah no real way to work out ve apart from engine dyno ve sheet

[Doctor Bob]

The VE tables are not really Volumetric Efficiency, its just a number relative to how much fuel you put in & calling it VE sounded like a good idea at the time

[yoda69]

I agree with Dr Bob.
I tried to do something looking at one of Holden202's log of an ecotec with a MAP sensor.
My calculated info didn't look much like the VE table at all.
In the end I put it in the too hard basket and gave up.

yoda69

[kelvin]

I've mentioned before about a new cam in my VN and running very rich at idle (I now have a black garage door). I assume the 'hot' cam being more inefficinet at low revs needs a change to the VE table in this area. To correct that would I then gradually lower the figures in the idle area of the map, until it runs better. And what sort of changes would be safe.

[Jayme]

you would put a wideband in your exhaust, then change the VE at each point on the map till the Wideband reads the desired AFR for that cell.

[kelvin]

That sounds like the answer for me. I assume keep the standard O2 sensor in one side and use the wideband on the other with no connection to the ECU. I've been looking at widebands and controllers and they are a bit expensive. I would like to just install the sensor and just measure the voltage with a multimeter. Is this possible.

[delcowizzid]

no you need a controller for it have a look at the naw_7s here its pretty cheap and works well for the price www.14point7.com

[antus]

Also be aware that there is an idle fuelling table as well as the low end of the main VE table. If you put a comms mod in your ecu, and run OSE12P then you can connect the naw_7s to the ecu, and then you can see all the engine variables together with the wideband data as it happens. For idle maybe you could just let it sit and watch the naw display, depends how far you intend to go with your tuning.