Metering 900 g/s airflow with MAS ???

[charlay86]

Thanks charlay86,
What did you type for the MAF search on google ?
Also, you saying your code is limited 511g/sec ?
IAm I able to get hold of it ?

Turns out the MAF sensors I was looking at might have been ford ones lol, but you can probably use a LS7 card style MAF in a larger tube (but that would hit the 511g/s limit anyway so prob overkill).

Yeah unfortunately we havent fixed the 511g/s limit yet, but you would have to be filling your cylinders to > 3.35 bar (map) at 35°C at 6000 rpm to hit that limit.

We haven't released this software publicly yet as it is still in testing phase, but it will be another upgrade to the enhanced factory bins.

[CKATM]

Turns out the MAF sensors I was looking at might have been ford ones lol, but you can probably use a LS7 card style MAF in a larger tube (but that would hit the 511g/s limit anyway so prob overkill).

Yeah unfortunately we havent fixed the 511g/s limit yet, but you would have to be filling your cylinders to > 3.35 bar (map) at 35°C at 6000 rpm to hit that limit.

We haven't released this software publicly yet as it is still in testing phase, but it will be another upgrade to the enhanced factory bins.

Yeh, looking into the Chevy Tube Type, you can increase the tube size and raise the flow rate with the same sensor output.


I also read somewhere that wideband O2 sensors are required for logging, is that right ?
Any specifics I need to know about what to buy, and can anyone suggest where to buy something suitable for the VS ECU ??

[Holden202T]

yes for what you are planning i would definately recommend a wideband.

i've had no issues with the 2 inovate motorsports (LC-1 and MTX-L) units, and you can get them in Aus from http://highway66speedshop.shop033.com/

[CKATM]

yes for what you are planning i would definately recommend a wideband.

i've had no issues with the 2 inovate motorsports (LC-1 and MTX-L) units, and you can get them in Aus from http://highway66speedshop.shop033.com/

Thanks for that, looks good, do these replace the standard O2's or run parallel ?

[The1]

it's best to weld another bung in each bank and run it on it's own. The next enhanced mod version will add two inputs so you could run two wideband controllers one in each bank if you wished and feed both into the ecu for datalogging.

[CKATM]

The "cylair" variable is Cylinder Air Mass, in milligrams (i.e. the mass of air in each cylinder per combustion cycle).
To convert that to mass air flow you would multiply it by engine speed, and then to get the MAF sensor frequency you would have to look up the frequency curve for the particular sensor.

For VT/VX I have code that allows spark (and fuel) control up to 1650mg/cylinder (possibly higher if necessary) as I have added another set of spark tables.

Currently the other limitation is the mass air flow variable only allows flow rates up to ~511 grams/second.

from a quick google search I have found that there are MAF sensors available that can measure up to 850g/s

correct, if the MAF's range is under 14000hz then with the current code you can change the reference in the tune at any frequency under that between 0-511 G/S

Obviously with rewritten parts of the code it could go higher than 511.

The VS-VY ecu's peak out at 16000hz hardware wise but found a couple on the bench not fully stable over 15000hz and at the time there wasn't any found MAF's that would go above 14000hz so only wrote the code upto that.

Can I compensatre this by fooling the ECU- eg. Running a larger MAF (which outputs up to 12000 or 14000hz, and entering a smaller injector size than is actually fitted ??

[antus]

I wouldnt try fooling the ecu, you might be able to work around one problem you'll create others at the same time and it'll become a pain in the ass to make it work properly. To do it right you'd need to modify heaps of tables. Are you sure your going to hit the limit? I would suggest just building it and seeing what happens, and if you do hit it, then for the $ you have spent on the engine it would be worth getting a copy of kalmaker workshop for the engine as they can meter more air. Since its all based on delco factory code, it wouldnt be hard to swap from one to the other if you find you need it.

[Holden202T]

i have one word for all this uncertainty

MAP

[charlay86]

I totally agree with Antus, it's much better if you don't have to fool the PCM.

How fast are you planning on spinning this thing?
Something to consider is that the standard ignition system is only really designed to work properly up to 6400 rpm.

If you can approach the 511g/s limit I'll see what I can do about extending it.

[CKATM]

I wouldnt try fooling the ecu, you might be able to work around one problem you'll create others at the same time and it'll become a pain in the ass to make it work properly. To do it right you'd need to modify heaps of tables. Are you sure your going to hit the limit? I would suggest just building it and seeing what happens, and if you do hit it, then for the $ you have spent on the engine it would be worth getting a copy of kalmaker workshop for the engine as they can meter more air. Since its all based on delco factory code, it wouldnt be hard to swap from one to the other if you find you need it.
antusSite Admin Posts: 1700Joined: Sat Feb 28, 2009 6:34 pm

I totally agree with Antus, it's much better if you don't have to fool the PCM.

How fast are you planning on spinning this thing?
Something to consider is that the standard ignition system is only really designed to work properly up to 6400 rpm.

If you can approach the 511g/s limit I'll see what I can do about extending it.

Firtly fellors, I want to say I appreciate the help yr giving me here.


With the engine, It'll probably be turning to around the 7000 mark (always hard to know till you've actually run new combinatios).
I have a VRAM & interface coming from you guys for both a VS PCM and also an 808 ECU. I'm going to have a play with them on some stock cars so I can learn exactly how all the tables work and are configured (as I'm probably thinking of too many ideas without knowing how it'll effect other stuff in the calibration). I think I'll need to do that before I can start working towards tuning it with the turbo- so I know exactly what and how many tables I'm dealing with.
I've also bought a wideband o2 guage kit I'll be setting up to use as a tuning aid.
Looking at the HP i want to make, I'm pretty sure it will go over the 511g/s. When I was talking previously about the boost I want to run, I'm only estimating and not 100% sure of what I'll need to run (the target HP is the determining factor of the boost). I know that the 'Ford guys' are running about 20lb boost to get around 570hp at the wheels with 98 pump gas).
I have found some MAF's ex the US that'll metre up to around 900g/s with a reported 12000hz odd range.
***Isn't Kalmaker limited with total airflow also with MAF ?? I know they have a 3bar prog for the VS though, but there's still a limit of 3 bar*****
I guess I'm keen to stick to the VS factory PCM if possible, I also want to have control over the transmission, and also retain the factory integration with the BCM, plus not have to worry about the rewiring of it (but this isn't the primary concern).
Even considering the HP i want to produce, I still want to keep it streetable which is why I'm going Turbo for this one.