ECMlink Real Airflow with Speed Density

[GSXDNA]

Couldn't find any solid info on this, but I've heard the airflow measurement in ECMLink isn't accurate if you're running speed density. Well, I'm running SD, and my log (attached) says I'm flowing 67lbs/min at 25psi on my 6-blade hx40 on the .70 a/r housing. I'm just starting to break in my 9:1 2.3L stroker. The HP estimate is only like 470hp, so something isn't adding up. The car certainly doesn't feel like it's making any more than 400-450hp.

Any advice on how to get the real airflow numbers? Or, is this somehow accurate?

 

[donniekak]

If you have the injector size correct, and do all the tuning in the da tables it's fairly accurate.

Running out of pump or injector can throw the numbers off as well, due to trying to compensate for the lack of fuel.

 

[bastarddsm]

67lbs is probably inflated. I'd suspect your somewhere around 54lbs/min

 

[GSXDNA]

If you have the injector size correct, and do all the tuning in the da tables it's fairly accurate.Running out of pump or injector can throw the numbers off as well, due to trying to compensate for the lack of fuel.

Interesting. Well, I did do some of my fuel tuning in the config settings, so maybe that's causing discrepancy?

67lbs is probably inflated. I'd suspect your somewhere around 54lbs/min

Low to mid 50's sounds more reasonable - do you have any math or logic behind that?

 

[jakelandry]

Before reading any of this I don't have access to my computer right now so none of this is specific to your car or log.

From my experience, significantly less people actually know how to properly tune their cars than you would expect. Inserting ballpark values and using correction tools in link is not the way to ensure everything is properly calibrated.

I've always got my logger to accurately meter everything by focusing on dialing in the injectors to match known constants on the car rather than dead time values for specific injectors. Essentially I've always started with the global suggested for an injector of x size. From there I don't touch the default sd table at all. Dial in ltft and stft to zero. Then you get to the important part. You have to move your airflowperrev to the proper range.

The reason I say this is the best way is because you can use only ve values, global, and dead times and make everything run flawlessly. So people normally do that, get incredibly inflated ve values, and think their car is tuned cause it is running great. The entire point of having a logger is to get the most accurate results you can to make comparisons and monitor your engines activity which people overlook when their car runs good.

So back to the airflowperrev part. Every variable in tuning is dynamic in the sense that if you change something, like global for instance, you can just inversely change a corresponding variable, like ve, to make the car run the same as before. So there's only a few "constants" known when tuning our cars and most of those actually can't be considered constants cause they're changed so much by the other variables. So when dialing idle you have to focus on airflowperrev because it's the only thing that shouldn't really change from setup to setup. People can say it should be x y or z all they want but that's an entire different argument.

Once you've dialed the fuel trims to zero you have to manipulate global and ve until you've got both airflowperrev at factory spec, and fuel trims at zero. It's a pretty big pain in the ass to be frank because as you change ve you'll also have to change global because you're trying to keep 2 things in control at once but once you get those two things to match you know your injectors are properly dialed in. From there you use afrest and a properly calibrated wideband to ensure the car is accurate on its afr's throughout the rest of the spectrum since it uses afr and your now calibrated fuel settings to determine everything else.

A few things to note: a stroker motor will effect airflowperrev and I would do quite a bit of research before just assuming it would be .30-.32 like everyone suggests because youll be starting from absolute scratch again if you try to re-dial in airflowperrev. Also let it be known that I am not the best tuner alive. These are simply observations I have taken from sitting in my driveway for hours and hours trying various idle settings. I've analyzed my cars airflow against 70-90 times, weight, drag strip results, etc and it's pretty much spot on. Another thing is don't be alarmed if your ve isn't 115% at its max like everyone else seems to believe is accurate. Mine peakes out around 82% Try it all out for yourself or disregard it completely. Makes me no difference.

Also for reference, I logged 62-63 lbs/min at 37 psi on a 62mm hx40 with a .55 hotside. I would be amazed if you nearly maxed a hx40 flow map at 25psi.

 

[bastarddsm]

Gsxdna. ((Boost+14.5)/14.5)*cid*(rpm/2)*.07/1728

 

[henrysan]

Your speed density table is inflated, add fuel from global fuel so your max values from speed density are around 100-105. Try to get boostest and actual boost to match from 5500-5800 rpm, this will give more accurate airflow estimates.

 

[jakelandry]

After looking at that log you have significantly larger tuning issues to work out before you worry about your airflow being accurate. Your SD table is terribly inflated. You used the fuel sliders in general. Your wbfactor is way off. Your fuel trims are terribly off. You would probably be better starting from scratch honestly. Not trying to be a negative nancy but it all needs to be retuned.

 

[GSXDNA]

Thanks everyone for all the replies. Looking at all this, I do think the SD table being inflated at certain points is likely the cause for the airflow inflation. Doing some quick math to back out that inflation, looks like I'm actually closer to 55lbs/min, as bastard DSM originally guessed... Which makes much more sense.

I know the tune has a long way to go. Its important to me that I actually learn the right way to do this (and the theory behind it), rather than me just paying someone to hand over a file. I know many of the basics, but am not too familiar with Speed Density, and how the tables should be set up.

If there's any gurus out there willing to teach me, feel free to PM me...I'm willing to pay for the knowledge to set it up right.

But, until I find someone willing to help teach, the latest tune I made (however hacky it may be) is still resulting in 14.7 cruising afrs, 11.5-11.7 afrs under wot, good timing, zero knock, and 565hp/460tq @ 30psi on 50/50 91/E85 (according to link - new log attached).

There's still some mechanical issues I need to sort out though before I waste any tuners' time..primarily spark issues. Still on stock ignition system, and starting to get some breakup above about 460 hp. After I resolve that, maybe I'll more actively search for a tuner to help me.