If it's a newer Gen4 ECM running in MAF mode then spraying on the IAT doesn't really change your fueling. If it's an older Gen3 PCM and you are running in speed density then do not allow it to spray on the IAT sensor, it will give false readings and richen it up a LOT if using factory fueling iat/ect bias tables.

I've tuned plenty of Gen3 PCMs in SD with it both hitting the IAT sensor and without and I much prefer it without in these situations to keep fueling more accurate and stable.

 

It will only richen as to what the tuner has in any tables, that's the tuners job to ensure it's all right. It would be crazy to only tune parts of a setup and then just hope others are correct for the application in hand

And I still dont see how anyone call it a false reading. A reading taken before the nozzles is false, because it is not a reflection of what is going into the chamber. In fact it wont even be remotely close because it hasnt taken into account any cooling effect.
It would be like placing the charge temp sensors prior to the intercooler then assuming it's correct.

I guess perhaps one of the differences here is I dont spray all the time. I only spray when actually racing and there might be a hint of traction to allow the use of any power made.
Which for most road/race/track/airfield setups it just isnt of any huge benefit to me.

 

If methanol is hitting the IAT sensor it's going to read colder than what is really going into the motor and that has a very direct effect on the fueling in a speed density tune no matter how it's tuned. Sure you can play with the bias tables to minimize this effect but it's still there and it will always play a role in fueling in a speed density application, as it should. I'm not going to argue about it, just pointing out how it works and the effect it has depending on the computer being used. Of course it's the tuners job to ensure it's all right and nobody said anything about only tuning parts of a setup, just giving my opinion on what I've seen over the last 13 years and what tends to work best.

 

I can agree to disagree, but that’s a matter of opinion and what I suggest is not “wrong”.

I was trying to say… The only data worth a damn you get form a saturated sensor is if the system is on/off. Turning what could be great data into an on/off indicator.

The small amount of extra charge cooling does not need to be compensated for IMO. The actual change in the overall charge temp is tiny. Figure a 6.0 at 6000 rpm and 85% VE flows roughly 15,300 liters of air per minute. So 242,510 gallons per hour. Compare that to the typical 12-15 gph worth of Aux INJ. nozzle.(.002%) It’s like pissing into a hurricane and expecting a big temperature shift.

The hair dryer test proves the changes aren’t linear, more CFM will only evaporate the fluid more quickly and further skew the readings. Bottom line… The sensor isn’t designed to work in a wet environment and won’t report temps correctly in one. Arguing otherwise is ignorant. Arguing corrupt/skewed data is as good as uncorrupt data is also ignorant.

Air travels fast in charge piping. The reading at the IC exit VS the valve entry point isn’t going to require any drastic changes in the tune. A 30-100*+ drop in IAT from a saturated sensor can change the tune considerably if using a factory ECU. I’d see below ambient temps with straight meth spraying 10” upstream of my IAT sensor. This is why I choose to inject the majority of the water/meth as close to the TB as possible. Then use a baby nozzle pre-turbo for the miniscule air charge cooling and wet compression benefits. Even doing this, the post IC IAT temps would swing a few degrees from the pre-turbo injection.

Sensor placement and water/meth percentage makes a big difference. I’ve yet to see a system that vaporized the aux inj. mix completely in the charge piping. Make a pull with the typical 50/50 kit and pull the charge piping right after. The piping will be wet, I’ve done it many times.

Some non-intercooled setups may vaporize the mixtures, but my sub 120* charge temps aren’t going to vaporize water instantly. I’d think you’d need to reach the boiling point of the fluid to vaporize it instantly/completely? Meth’s boiling point it 148* and water is 212*. Why do you think its instantly changing to a gas in a typical intercooled setup? If it were doing this why does it have such a drastic impact in the CC? You want the liquid mixture in the CC where it will have the highest temp delta and do the most work when it flashes. I’m usually well under 148* at 20+lbs. I wouldn’t think even 100% meth during operation would instantly flash, it will still coat and evaporate from the sensor bulb as it’s being sprayed in most cases. (All cases I’ve worked with)

 

We shall definitely agree to disagree.

But we do agree on one point...sort of. The hair dryer test is meaningless as you do agree...reality is like pissing into a hurricane. Not pouring water on a still day as the hairdryer test is more akin to.

I've certainly never seen charge temps drop below ambient on any car I've worked at, nor would I expect them to.

Each to their own really, if it works for you, that's ultimately all that matters.

As said, a reading is a reading, it doesnt really matter. It's how you interpret and use that reading that matters.