air fuel question

[Otto J]

Just tryin to figure something out,If i log a pass and go into the fuel map the higher the rpm around 5500 the car goes rich (10.75)Now that means that i must lower the VE number on the map to clean it up<
But doenst it seem strange that at a higher rpm same boost the VE number wou;d be lower
IE 5300=11.5-VE#57
5600=10.7-VE#55
It just seems to me that the higher the RPM the higher the VE would be not vice versa
Any input on this.
If anyone has an 83# program i can see please email it to me
Thanks Otto

 

[tazgn]

I don't necessarily understand it either, but mine does the same thing. I have my 83# program, but I'm still working on it, so I don't know if it would be of help. But yes, my VE #'s also go up then back down as boost and RPM go up.

Derrick

 

[Otto J]

maybe as rpm increases the actual Volumetric effieciency goes up that is why the numbers go down
Otto

 

[bigpsi94]

"With a properly calibrated base fuel table, the cell values should be highest at the engine’s peak torque RPM and then decrease beyond peak torque." Could this be the reason?

 

[Otto J]

That does make sense, Just in a one way frame of mind,You think the higher the engine revs the higher the VE numbers should be,But if the wide band 02 is that accurate,then my VE numbers need to be lessened up top.
Otto

 

[bobc455]

The VE numbers typically peak out where the engine is making the most power.

The engine will be consuming more total air at it's highest RPM, but the air volume/rev will be lower (hence the lower VE number at the top of your table). It's harder to fill a cylinder at higher RPM because the air can't get in there fast enough.

Could your engine fill the cylinders completely at 12,000 RPM? Probably not. Because the cylinders won't be full, you will have a lower volumetric efficiency the higher the RPMs.

Make sense?

-Bob Cunningham
bobc@gnttype.org

 

[Otto J]

it all makes sense, but mine may also be that i am having a valve float problem at those rpms, i am fixing that problem know,and will retest them.
thanks for the posts
Otto