Update for those interested....

[Drone51]

can you just not put like50lb/min at 11500 and call it a day (you really just wanna put right above the highest value you would be hitting) and scale the other numbers

why would this not work


(I have not played around with hp tuners really but it sounds right no)

[HAZ-Matt]

No, not if the MAF itself outputs greater than 11500Hz.

There has been confusion in every thread about the MAF. The table in the PCM tells the computer how much airflow each output frequency correlates with. The table ends at 11500Hz. The MAF itself (the sensor) is scaled in some way that if it detects low airflow, it outputs a low frequency, and increases frequency output as airflow detected increases. Maxing the MAF in our case means that you are flowing more air than the airflow when the sensor outputs 11500Hz.

The fact that Patrick can hit 10psi at certain temps means that the new MAF is scaled so that 11500Hz correlates to a higher airflow than the older one.

The PCM table should be a given for a certain MAF, and the scaling should be provided by the manufacturer. Fine adjustment should only be necessary to correct for variances in airflow given the intake setup, but I think those should be minor.

EDIT: Out of curiosity, what was the airflow of the old MAF at 11500Hz, and what is the airflow of the new MAF at 11500Hz? I am a little confused about the way HPTuners would read the airflow data in the log, since I would assume that it gets it from the computer. This would mean that the log would show whatever value you have in the MAF lookup table for 11500Hz.

[RGB]

The company that sent you the MAF should have included the calibration for Hz vs g/s. To me your results only make sense if you had a 20 lb/min MAF, replaced it with a 40 lb/min MAF, when you wanted the 60 lb/min MAF (800 CFM). Did someone do you a "favor" and send you the smaller MAF for your "lowly" V6?

[HAZ-Matt]

Originally posted by RGB:
The company that sent you the MAF should have included the calibration for Hz vs g/s. To me your results only make sense if you had a 20 lb/min MAF, replaced it with a 40 lb/min MAF, when you wanted the 60 lb/min MAF (800 CFM). Did someone do you a "favor" and send you the smaller MAF for your "lowly" V6?

This seems plausible.

[Linxs]

Originally posted by HAZ-Matt:
EDIT: Out of curiosity, what was the airflow of the old MAF at 11500Hz, and what is the airflow of the new MAF at 11500Hz? I am a little confused about the way HPTuners would read the airflow data in the log, since I would assume that it gets it from the computer. This would mean that the log would show whatever value you have in the MAF lookup table for 11500Hz.

If i am reading this correct then u are right (according to my information) I posted above how the MAF reads transfered and changed in the PCM. Nocutt comfirmed that this information is correct. Basically, a Hz signal is received by the PCM. The PCM then cross references this to the tuneable table where you can put LB/min (in imperial) or G/sec (metric). This reading is what the PCM uses to calculate how much fuel to dump. The greater the number the more fuel it'll dump. All this number does is configure fuel dumping. It has nothing to do with how much air is actually entering the TB other than the cross referance of the Hz to lb/min for fuel calculation.


Edit: and this is the LS1 600HP MAF from SLP. I have a theory as to why I am maxing it but I want to talk to someone before I post it.

[HAZ-Matt]

The theory isn't because you have more than 600HP is it? Because I think it is more like ~380HP at 39.9lb/min airflow (I did a guesstimate of BSFC, I didn't want to calculate it) ;)

EDIT, had the A/F wrong the first time...

[ February 22, 2005, 01:21 PM: Message edited by: HAZ-Matt ]

[Linxs]

Originally posted by HAZ-Matt:
The theory isn't because you have more than 600HP is it? Because I think it is more like 380HP at 39.9lb/min airflow (I did a guesstimate of BSFC, I didn't want to calculate it) ;)

Actually, I think I am pushing 400 at the wheels @ 10-11 PSI. But to answer your question no. Also remember 39.9 is being heavily compensated in the PE table right now. I am dumping 50% more fuel in the upper RPMS.

[HAZ-Matt]

Originally posted by Linxs:
Actually, I think I am pushing 400 at the wheels @ 10-11 PSI.

Yeah, I had the A/F wrong the first time and got 350 with BSFC around 5.5.

I don't now what is really being flowed, but at 39.9lb/min it would be somewhere between 373 and 447HP depending on if BSFC is closer to 6 or 5.

But then again, there are a lot of variables in the calc that I just fudged, so really in the end I suppose I was just throwing out numbers. [img]smile.gif[/img]

[phoenix64]

Originally posted by Linxs:
</font><blockquote>quote:</font><hr />Originally posted by HAZ-Matt:
The theory isn't because you have more than 600HP is it? Because I think it is more like 380HP at 39.9lb/min airflow (I did a guesstimate of BSFC, I didn't want to calculate it) ;)

Actually, I think I am pushing 400 at the wheels @ 10-11 PSI. But to answer your question no. Also remember 39.9 is being heavily compensated in the PE table right now. I am dumping 50% more fuel in the upper RPMS. </font>[/QUOTE]Why are you using the PE table?

I know everyone here thinks I'm doing this wrong, but using the MAF is much more accurate, and easier, IMOH.

[RGB]

If you put 40 lb/min in the top cell when it should be 60 lb/min, then you would need to band aid it with adding fuel with PE. But would not explain seeing 11,500 Hz if you are not making 600 hp.

[ February 22, 2005, 02:03 PM: Message edited by: RGB ]

[Linxs]

Originally posted by phoenix64:
</font><blockquote>quote:</font><hr />Originally posted by Linxs:
</font><blockquote>quote:</font><hr />Originally posted by HAZ-Matt:
The theory isn't because you have more than 600HP is it? Because I think it is more like 380HP at 39.9lb/min airflow (I did a guesstimate of BSFC, I didn't want to calculate it) ;)

Actually, I think I am pushing 400 at the wheels @ 10-11 PSI. But to answer your question no. Also remember 39.9 is being heavily compensated in the PE table right now. I am dumping 50% more fuel in the upper RPMS. </font>[/QUOTE]Why are you using the PE table?

I know everyone here thinks I'm doing this wrong, but using the MAF is much more accurate, and easier, IMOH. </font>[/QUOTE]Because i have not had a chance to convert it over yet. We had it set like this because of the MAf problem. Now that it looks like I can tune for 10-12 PSI I'll be converting it over to the MAF table and let it tune the car instead of putting it in the PE table. I am not going to pull it out fully, The MAF is slow to react where are the PE mode kicks in right when i need it.

[phoenix64]

What do you mean by slow to react?

The car actually goes lean and then richens up?

[Linxs]

Originally posted by RGB:
If you put 40 lb/min in the top cell when it should be 60 lb/min, then you would need to band aid it with adding fuel with PE. But would not not explain seeing 11,500 Hz if you are not making 600 hp.

Think about it this way. Compare a 4 inch pipe to a 2 inch pipe. Say you can push 6 PSI out of both pipes. If you compare them it would feel like the small pipe is pushing more air because it has a small area. My theory is essentially the same. If I upgrade my piping after the intercooler to say 3” or 3.5” it’ll have more area mass and will not be as concentrated in the center of the new MAF. Does that make sense?

[Linxs]

Originally posted by phoenix64:
What do you mean by slow to react?

The car actually goes lean and then richens up?

The MAF is slow to react to sudden air flow changes; where as if I have fuel dumped at a certain RPM the computer will dump it right then. I just have to find a happy medium between the 2.

[RGB]

/QUOTE]Think about it this way. Compare a 4 inch pipe to a 2 inch pipe. Say you can push 6 PSI out of both pipes. If you compare them it would feel like the small pipe is pushing more air because it has a small area. My theory is essentially the same. If I upgrade my piping after the intercooler to say 3” or 3.5” it’ll have more area mass and will not be as concentrated in the center of the new MAF. Does that make sense? [/QUOTE]

Yes, screen in, even flow to screen, etc all matter in the MAF giving accurate readings