I just want to be sure I understand the VE table correctly. This is the fuel curve, right? More fuel as RPM x MAP increases.

This shot is from a stock 350 TPI chip with speed density. This basically follows the power curve of the TPI, right? In this case, peak power is where the most fuel is given?

 

Not exactly. VE follows the torque curve closely. Power is horsepower. VE is the volumetric efficiency of the engine. Even as the HP increases the VE decreases. There is more HP because the engine is spinning faster. There is less VE as the engine can not take in the same amount of air per rev as it can at the torque peak.

So if you would like to rough in a VE table have it follow the expected torque, not the HP.

One thing that is missed is that the injectors are sync'd to the firing of the spark plugs. So as the RPM increases so does the frequency of the injector firings. Hence more fuel for more HP as the engine spins more times per minute.

RBob.

 

How would you best define "Volumetric Efficiency"? My understanding of the term is very fuzzy.

Volumetric
Volume of fuel? Volume of air? Volume of what exactly?

Efficiency
??

Beyond that, what do the numbers represent exactly? I understand how the VE numbers work with the BLMs and Integrator, but don't know what the VE numbers represent.

 

its 100% of the air a cylinder could contian.due to the fact thet the cylinder head, intake port intake manifold TB etc all impede airlfow VE is rarely at 100%.these are usually reffered to as pumping looses.

with a properly sized injector a 400hp SBC shouldnt really exceed 90% VE in any way. the top winston cup teams are lucky to get 100% ve. some get 102% but most get around 98% ve.

VE= volumetric effiency the representation of the thoeretical amount of air your engine could possably ingest

 

So VE = (actual volume of air and fuel taken into cylinder) / (total cubic inches in cylinder)
This would have to be at the end of the intake stroke.

Now what do the numbers in the chart represent? The values that I can change? I think I'm missing the connection between the values I can change in the VE table and the resulting volumetric efficiency.

I appreciate the help.

 

ecm uses the ve or airflow in the table to calculate injector pw.

 

It now makes sense to me.

Thanks again for the great info!

 

So having a VE table with higher VE values across the board means that the engine is perfomring better then another car with lower VE values across the board??

So the higher the VE values you have with 128 BLM's you have a good engine correct?