I need to know why is so important, and what is it come from?
on the datalog tables and maps you have RPM versus loads - what unit are these load numbers in? I just want to make better sense of this concept.

 

I've heard that the load values are in kPa (kilopascal) value, bt there are disagreements. We do know that it is a calculated value that includes the MAF reading, barometric pressure and some other things (I'm a little foggy on this as well).

Tephra might be the best guy to break it down since he's the one who recently found the "real" 2-byte load values that are used by the ECU that include all of these variables. Mrfred could likely help as well as he's don't a lot of work with the multiple load values that the ECU uses.

 

Load is basically how much air the engine is eating up. Its important when tuning to know what cells the ECU is accessing and using "2byte load" is the most accurate way of doing this.

units wise, load roughly equates to kilopascals, ie a load of 250:

(250 kilopascals) - (100 kilopascals) = 21.7556607 pounds per square inch

however this is a VERY rough estimation, you shouldn't really be using load to work out your boost pressure, as I said the main reason for logging 2byteload is working out how the ECU is operating..

 

Load for a MAF-based car is proportional to [air volume]/[rpm]. So its proportional to the amount of air the engine is gulping per revolution. Engines generate torque. The more air/rpm, the more torque the engine has the capability of generating.

 

This is how I was explained.

Load cell
100 = 0 boost
200 = 14.7
300 = 29.4

You can guesstimate the ones in the middle. Or you could just buy a JDM map sensor and you know what you boost is without trying to figure it out with load cells.

 

I've had Evos hit 310 load with 28 psi and 300 with 27.5psi, and some hit 300 with 25.5psi so 29.4 for 300 isn't very accurate.

 

i hit 290 with 24 psi

 

This is just more proof to get a JDM Map sensor.

 

Why? If it's still being left a maf-based load system all a map sensor is going to do is tell you what pressure you're hitting just like a boost gauge. Pressure and load are 2 different things to the maf-based setup, although when tuning to the extreme it is nice to see what your exact pressure is, even though it really won't help one bit when tuning your load percentages...I went from hitting a 220~% load when I first started tuning to hitting the mid 240's after a little work with the same boost pressure, and now even higher after a few more parts and tweaking.