Quote:
Originally Posted by Xan
To Stillen: I searched the thread but couldn't find it, are you using the V-3 SCi-Trim or the V-3 Si-Trim?
Edit: Reading through the thread I was kind of surprised with some people wanting "speed density" air measurement.
This is less accurate as your not measuring the actual air mass, but using a big lookup table and some sensor inputs to come up with an air mass estimate.
Additionally for the person asking about the MAF before the supercharger and the temperature difference. This doesn't affect the air mass, as the same air mass still flows passed the MAF, just at a lower temperature/higher density. If the MAF can deal with the higher flow, the measurement of the mass of the air is still correct. Where it does affect is that hot air can lead to knocking, however you can tune for this by not using too much ignition advancement. And the use of their air-to-water intercooler also reduces this as much as possible by cooling the air back down before it enters the cylinders.
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The point that you are missing is that even though you may be able to tune for the miscalculated intake air temps to quell knock, these are canned tunes at sea level and in different ambient temps. The ECU, in situations like this, need to be able to adjust for variables. Without knowing the exact temperature of the air from the MAF (measuring colder are due to 'draw through' that does not equate the hotter, compressed air going into the intake) the ECU cannot make the adjustments. This is why a "blow through' setup on a canned tune is a better option (though not close to perfect) than a canned tune on 'draw through'.
It's all well and good to have a
custom tune on an OEM N/A car using 'draw through', but when it's a singular map shipped all over the world and in drastically different environments, not so much. This setup should come with a warning of recalibration is recommended. We've had this debate over on NAGTROC quite a bit when discussing "e-tunes." Even on an OEM F/I car that is calibrated for 'draw through', a one-size-fits-all approach to tuning is a bad idea.