nitrodann

Vlad yours and Pats results testing heatsoak are different.

maybe the FFS heats the air all the time? I dunno.

As for your comment about leanness, thats cos they are fairly untuned and pat has gone too far the other way.

Andrew my point is that Pat is right in saying that if the air changes temp dramamtically from intercooler end tank to cylinder it would be better to compensate accurately and we have no idea how much it does change temperature.

Dann

Savington

iTrader: (31)

But there's no way to compensate accurately for things like valve temperature (at least not with equipment that is available to consumers or probably even prosumers like you/I). If I had to guess, I would say that OEMs use computer modeling to guesstimate at that and then use cylinder pressure data to validate that as best they can. Nobody is suggesting there's a way to accurately compensate for things like cylinder head or valve temps with the bits we have available.

What Pat is suggesting is that there's an air temperature difference between the outlet of the IC and the air in the coldside pipe. What Joe and I are saying is that's absolutely ridiculous given the speed of the air and the orifice through which it's traveling.

Joe Perez

iTrader: (8)

This is one of those interesting situations in which you are 100% correct, and yet that knowledge is utterly useless.

When someone invents a technology which allows us to cheaply and accurately measure the temperature of the air inside the combustion chamber, after the inlet valves and yet prior to the ignition event, we can re-visit this conversation.

Until then, since we are stuck dealing with sensor technologies which are highly susceptible to measurement error induced by case temperature, and in which the magnitude of said error is greater than the temperature gain of the air as it travels 2-3 feet in a mostly non-thermally-conductive environment, the best we can do is the locate said sensor in an area which minimizes externally-induced heating of the case.

And, lest someone be led to believe that I'm writing this with anything even resembling a sour attitude, here's a kitten hugging a potato:

18psi

iTrader: (76)

Data and testing needed to prove your outrageous claim that the kitten is indeed hugging the potato

Girz0r

iTrader: (1)

Fwiw I'm not knowledgeable in tuning and may have incorrect information. But thinking on a physics level...

To go along with what was said about where to measure IAT, where does it end, intake, vavles etc. Wouldn't you want the colder IAT reading to comp for extra fuel? Even just that smaller amount %?? With the amount of flow going into the intake, IAT is miniscule in difference when it's pressurized after the intercooler. Tiny amounts of changes, micromanagement tuning for accuracy? Why not put IAT in the 4 intakes to each cylinder and get an average?

Point being, does it matter.

deezums

iTrader: (3)

It doesn't matter, you can tune out the intake manifold and valve heat because they should be near constant. As we all know, ideal gas law means nothing. If I try and correct air density like that I'll be rich as **** at night and spitting stalling lean at lunchtime.

Put it outside the engine bay. My slow MS2 probably can't even shift gair in small enough percentages to matter, and I doubt a ms3 is much better.

When the air is really moving, on power, the sensor should react much much faster. I don't care enough to check, because gair doesn't need to shift hardly at all on my tune, I nerfed the hell out of "ideal gas law."

aidandj

iTrader: (5)

To put the bullshit to end finally I made a video.

Shitty production. But quality data. Temp skyrockets with external heat source. Even when its not being applied.


Data points @ :30, 1:10, and 2:48

patsmx5

iTrader: (16)

Good for testing it and making a video. But your test is flawed if you think the sensor body alone is causing that 50*f temperature rise.

The engine was not running, so there was no airflow at all across the sensor. Thus it's just measuring whatever the air temperature of the air in the intercooler tank is. You heated the sensor/intercooler end tank with a heat gun multiple times. I would guess after heating the end tank of the intercooler with a heat gun that long, it was above ambient by a lot, and your sensor was showing that. Not surprised it showed a 50*F rise, that's completely reasonable and I would guess the air inside that tank was about 50*F hotter than ambient after heating that with a heat gun.

patsmx5

iTrader: (16)

I run the stock AIT correction curve unchanged, and my car does not run rich or lean on hot restart, it runs at target.

I've already answered the heatsoaking it part. Test for yourself. Use a infrared temperature gun on a black surface for example to get a second reading. My intercooler pipe was black when I tested it, so I could measure the pipe temp, and air temp too. On a shutdown after restart condition, if I turn key on, engine off, and check the AIT temp vs pipe temp, they were the same. Cold start, same. etc.

EDIT: IR temp gun not heat gun....

patsmx5

iTrader: (16)

At WOT, yeah there's negligible difference I agree 100%. Air's moving too fast to gain much heat from the walls of the pipe.

After a 15 minute heat soak from shutdown, you still maintain there is no difference? None? I pull off the highway and park at a store, come back 20 minutes later the air in that pipe isn't heatsoaked? Or the pipe itself? If I start the car and let it idle, will the cool air from the intercooler be heated any by the hot pipe?

You insist this does not happen, but your opinion violates simple thermodynamic laws.

patsmx5

iTrader: (16)

You should test this yourself and post the data if you want to see what difference it makes. Put a sensor in the intercooler end tank, another in the plenum or near throttle body. Use an IR temp gun on a black surface (black painted, or put electrical tape over surface if not black to get accurate reading) and test and see. I can tell you from common sense that when you shutdown after driving it, the engine heat soaks everything in the engine bay.

patsmx5

iTrader: (16)

Here's how I did it.




Drilled tiny hole, installed thermcoulple, RTV to seal it, Zip ties to hold it/provide strain relief. Ran to 8CH EGT box.

aidandj

iTrader: (5)

Alright. When my new battery comes in I'll do another test.

patsmx5

iTrader: (16)

If you want a definitive sensor test, get a piece of sheet cardboard and poke a hole in it, stick the air temp sensor element through the hole so that the element is in free air and separated from the body of the sensor. Then put a fan blowing on the element, and a heat gun blowing on the body of the sensor. Idea test would be to have the fan running on the element for a couple minutes to let that stabilize at whatever the fans air temp is, then note that and hit it with a heat gun.

18psi

iTrader: (76)

your stock ecu controls the ait curve?
or by stock you mean whatever came with the ms3-pro?

Savington

iTrader: (31)

I never said it wasn't. Stop being deliberately obtuse.

I don't think it's heated substantially, no. I think I've stated that. Feel free to change my opinion with math/data, though. At idle, the air in that pipe is cycled three times a second. Can you quantify how much heat is transferred to the intake charge through that pipe (let's say it's a 2.5"x.080"x24" pipe) in that period of time?

patsmx5

iTrader: (16)

Actually.... yes it does.

But no that's not what I meant in that post. I run the default MS3 settings for AIT correction on the MS3.

patsmx5

iTrader: (16)

Glad we can agree heat transfer is real and happening. I have no desire to change your opinion on what substantial means to you. I wrote down some temperature data last year, but to be honest it's probably gone by now and I'm not going to make it up on memory. Yes I could quantify the heat transfer via some 1D approximations using thermo 1 math, but I'm not typing all that out.

Madjak

I run N/A so a few variables are removed. I get heat soak on my air temp sensor which is in a runner on a Skunk2 intake manifold. It will take 30 - 60 seconds of decent airflow over the sensor to drop the temps close to ambient like running on the track during a warm up lap... sitting idle won't change it much. Once running I see very little change in air temp throughout the run regardless of the temp of the motor (and also IM) and then when I pull in to the pits and airflow over the sensor is reduced, I see the temp rise fairly rapidly as the sensor heat soaks from a heated IM.

In my case on a 90 degree F day when the engine is already warm from a previous run, I'll see temps whilst sitting idle of around 140 degree F before dropping down to 100 degree F whilst I'm running. Pulling into the pits I'll see up to 160 F if I leave the car idle.

My sensor is an OEM Honda with a thin insulating gasket, 8" from the head in the runner. It can't be reading actual air temp because if that was the case, the air temp would drop immediately on WOT. Instead is slowly drops as the air flow over it cools the sensor.

This would be the same wherever the sensor is located... Runner, Plenum, intercooler.

Braineack

iTrader: (62)

do they?


I'd say it's like 10% and those are just NB owners and people who still put the AIT behind the radiator.