Discussion on some tuning theory

[pauly24]

Ive been looking at the the tute posted by swing tan " E38 VVE Setup Guide"

And Ive got some questions about the methods used.

First, the VE table is volumetric efficiency, so it lets the ecu know the amount of volume of air that is going into the engine at each RPM and MAP point. But what the car really needs to know is how much mass of air is entering the engine. So it can match it with the right amount of fuel.

Because of the laws of physics (PV=nRT), you can have say 80% efficiency at 2000rpm and 60kpa, but this volume of air can bring in say 200grams of air or if the temp is hotter it can bring in only 180 grams of air (numbers are completely made up) but you get my point.

So I understand this is where the intake temp multiplier comes into play.

But when you dial in the VE table, you are setting the intake temp multipliers all to 1.

So if you went out and tuned your VE table on a cool night, your numbers will be different to if you tuned it on a hot night.

Effectively saying your Volumetric Efficiency of the engine changes depending on intake temps, but this is untrue.

The volumetric efficiency stays the same (Car takes in same amount of air regardless of intake temps), it's the density of the air that changes which gives the different AFR results.

And therefor the intake temp scalars are what needs to be worked on.

When the ECU works out the mass of air from the volume, it obviously needs to know the density of the air. This density of air will only hold true for one temp. And whatever temp this is that the density is worked out from is the temp that ones intake temp should be at, AND THEN you will have a TRUE VE table.

Now someone reply and tell me you understand what I just said