How Speed Density Works. (Article I found) True??

[LSXtreme]

Read Below and the attachment. I would like to hear what anyone has to say about this dudes theory

He States.....
"From Physics to Speed Density
Doubt is not a pleasant condition, but certainty is absurd. (Voltaire)
Eventually I got tired of working off AFR % Error and Fuel Trims, and figured out that there’s got to be a better way of arriving at the final fueling. Also, once I found out that the VE in HPT/EFILive is not a real VE but some combo package of mass, pressure and temperature, I decided that’s a moving target. Combine the two, and you got an error prone method of aiming at a moving target—I have no idea frankly how we got any of our tunes working right this way."

"So all this stuff got me thinking: If Volumetric Efficiency is constant then the air moving through it should be calculated dynamically according to the conditions. Of course, our VE (from now I’ll refer to it as the GMVE) contains pressure and temperature. Thus, what I figured I needed is a way to convert from a fully tuned GMVE table obtained using historical methods, to a true mechanical, absolute VE. Knowing that, we can calculate back to GMVE, adjusting for any conditions we’d like! No more retunes. No more waiting for fuel trims to catch up. No more worrying about racing in the desert or mountains and suffering from a double penalty of bad air and a bad tune. Just start with your absolute VE, punch in fresh weather data, and out comes your ‘here and now’ GMVE table ready to flash."

Article is the attachment

[TiredGXP]

I see you've found some of Marcin's (Redhardsupra's) stuff.

He's got some pretty good ideas, although he does launch into some hyperbole from time to time.

I've had a few long conversations with Marcin; he certainly knows his math and physics, and has come up with some interesting concepts, and I think has some really good insights.

I've come to the conclusion that I need to take a more "practical" view of tuning instead of pursuing a theoretically perfect model (although I wish Marcin continued success in his quest). Given how many parameters we need to deal with, production tolerances in factory sensors... I can be satisfied in using AFR% error etc. to find the "least errors" tuning result.

[WS6FirebirdTA00]

Temperature and pressure will affect the VE table due to crappy calculations for IAT and what not. The issue is with density of air entering the cylinder, not so much the volume (that is varying). Not to sure I can agree with the statement, as I do not know all the details. There are IAT/ECT compensations by the computer (post '01) which, if setup correctly, should make accurate changes for VE tables based on barometric pressure changes and temperature changes. That could mean the VE table is a true VE table but we are limited by what we can adjust and how the computer compensates. Remember, VE was not designed as the primary fueling tables. We are going to need more options for SD tunes to allow us to compensate.

[redhardsupra]

oh man, i wrote that almost 2yrs ago, and I didn't realize how much more I understand this stuff now...

Mike basically got it in his post, Manifold Temp is an estimator, and unless we know how to calibrate it properly, we're kinda screwed. However if we did know how to do it right, then the VE table could truly a pure VE table.

if you want more on the topic, hit me up on aim, i'll talk your ears off

[WS6FirebirdTA00]

got ya, I didn't read it all, I was at work

[Souless]

I can vouch for redhardsupra, he is a stand up guy who will teach you alot about tuning. Probably more than you can ever take in. He is one of the smartest guys I know and will help you with anything.

Nakoz

[jimmyblue]

This (manifold temperature) is what I would really like to understand
as it goes right to the IAT, relocation, charge bias temp questions.

Specifically I am wondering if there is any way to move to a MAT
direct reading and ditch all the estimating.

[redhardsupra]

no, but if you move it you get to redo all the estimator calibrations