Measuring heatsoak vs actual AIT?
#103
Knowing absolutely nothing about water injection, I'd expect you'd want the water nozzle as close to the outlet of the compressor as possible, give the water plenty of time to change phase and soak up heat.
And IAT always goes post intercooler, either endtank or plumbing directly after endtank, outside engine bay. As expected, Aidans test shows that in steady even air temps the case of the sensor will skew temps bad. There's nowhere else you can put it.
And IAT always goes post intercooler, either endtank or plumbing directly after endtank, outside engine bay. As expected, Aidans test shows that in steady even air temps the case of the sensor will skew temps bad. There's nowhere else you can put it.
#105
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This is hard to do.
Last edited by Joe Perez; 03-21-2016 at 01:01 AM. Reason: grarmmer
#107
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The key point being simply that the water does most of its work inside the chamber during the compression cycle. Relatively little evaporative cooling occurs in the intake plumbing or the plenum.
You want as much of the water as possible to still be finely atomized when it enters the chamber. The further upstream you inject it, the more likely it is to pool out of atomization into larger droplets, especially if an intercooler is present.
You want as much of the water as possible to still be finely atomized when it enters the chamber. The further upstream you inject it, the more likely it is to pool out of atomization into larger droplets, especially if an intercooler is present.
#111
So to further a bit on the water/meth injection idea. Would you want to place the nozzle before the AIT sensor? For instance would placing it in the "hot side" of the intercooler endtank be a good place for it? I know some cars come OEM with intercooler sprayers like the EVO and some Japanese spec STIs but that is external and I've not seen people run it like I mentioned before. Usually it is always near the throttle body.
I'm sure water is probably ok to spray in front of the IAT sensor, but I have a feeling meth probably isn't that great of an idea.
When I'm spraying meth on the streets, I run a special tune for it. And when I'm running only water like at the track, I run a much more mild tune.
#117
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I would be concerned about measuring the air as being warm and then having it actually be cooler and more dense once it is then cooled by the injection. This could inadvertently make the mixture more lean.
#120
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Any cooling (and thus, density increase) which happens inside the chamber during the compression cycle is irrelevant from the standpoint of fuel metering, as it's a sealed volume. More oxygen cannot enter past the closed intake valves.