so i took a log on the way to work. This is over 17 minutes. I am only posting the IAT and MAT values but can post any addition parameters. The spike on IAT is a 2nd gear pull from 2500rpm to 7800rpm.

Looks like the MAT is consistently hotter then the IAT. And you can see what the outside air temp is - high today is 39*

for the record, i am running the perrin intake with the stock airbox snorkel in place to push colder air in. looks like it is working.

 

Interesting. That seems to coincide with about what Tephra is seeing with the sensor in the same location.

So, now we have at least two people with the sensor in the UICP (mrfred and I) who see roughly equal IAT/UICP-T while cruising whereas you and tephra see roughly 20-50F greater MAT while cruising.

All of us see rising post intercooler temps during a pull, as expected.

So the real question still stands...which is more representative of the true air temps going into the cylinder? Perhaps neither, and as 03whitegsr has stated, a correction table may be needed of some sort. I think the only way to tell for sure is to test the SD patch alongside a MAF, doing several pulls and cruising, calibrating AFRs from the SD data to the MAF data. That will tell us how much, if any correction is needed.

What I do find interesting in your plot above that may be pointing to some kind of heat soak/boundary layer/etc phenomenon is that your cruising temps seems to hover roughly 20F above IAT, yet after your pull, they seem to hover roughly 45F greater than IAT and seem a lot more choppy than before. You may have been doing a lot of on/off throttle driving here, so I don't know, but that's something to take into account.

I think this is all good data for the eventual SD patch.

 

I've been logging OEM JDM MAT for the last year or two on my Pocket PC, and have a live display as I drive. What I notice in particular is that IAT and MAT creep up at low cruise speeds, and they diverge. They converge again with more airflow through the intercooler and more throttle. MAT can even drop when you go WOT, and then rise again after the pull.

Some of these effects may be due to heatsink/heatsoak of intercooler/inlet manifold, and the relative effects of fresh, cool airflow compared with coolant or cylinder head heat flow. Some may be due to the large thermal mass of the large OEM sensor. However, it doesn't behave wildly differently to my old Subaru with FMIC and a very low mass fast acting K-type thermocouple just before the throttle body.

I have a cutout in the cool side of the airbox, and TB coolant bypass mod.

 

Who is going to test one of htose thermal gaskets like Hondata makes, to see if there is an effect on air temperatures?

EDIT: I see some of you may be using them. Any before/after results?

 

John, do you have a pic of what the JDM IAT sensor looks like? We were wondering if the tip is the same as the GM IAT.

Wreckleford, i have the hondata but only installed it when i installed the sensor so i don't have before and after. As of right now it looks like it isn't really doing anything which makes the only real advantage of having a reusable gasket. Then again i would like to get some logs in the same temp range as tephra and see if it does work.

 

I'd like to see a picture as well. The MAT sensor on the Evo X should be the same as the JDM Evo IX MAT sensor, so any pic of that would work too.

 

The IAT correction factor is an interesting concept. I like the idea, but I think there is the potential to get too carried away with it. At some point, there needs to be a division between manifold air temp and the temperature of the air in the "engine" (before compression and combustion). Do we really need to estimate/know the air temp at the end of the intake runner just before it enters the cylinder? What about the cooling effect of the fuel spray from the fuel injector?

One thing that surprises me a bit is how high the MAT temperatures are during cruise. I realize that significant amounts of heat pass from the head into the IM, but with the throttle butterfly mostly closed and a good vacuum in the IM, there should be a strong cooling effect on the air as it passes by the throttle butterfly. I'd really like to see someone get some MAT numbers before and after disconnecting the throttle body heater. Just don't do it in near freezing weather, or you'll likely freeze up the butterfly.

 

i can do this test in the future, but as you can see i fear something freezing. Then again, the throttle is mechanical so i am sure i could break it loose with my foot

 

Don't have a pic of the tip (never removed it from the inlet manifold), only the top which I put on Aktivematrix in Bez's speed density thread, but I can't seem to log into Aktivematrix and find the thread!

I didn't notice a huge difference after removing the TB water feed, the MAT reading gradually warms through a drive anyway, and the weather here is quite variable from day to day. I've not had the throttle sticking down to -4C (about 25F) here.

 

I wouldn't worry so much about that T/B "heating" the intake charge when you have 1000+ degree EGR gasses circulating through the intake manifold....

I blocked off my EGR port in the head as well as the coolant lines to the T/B and added a spacer to keep mine as cool as possible. Even after a long extended period of WOT, 1, 2, 3 and 4th gear pulls, you can pop the hood and immediately get out and touch the intake manifold anywhere and it's not hot at all.

The EGR gasses I can imagine provide plenty of radiant heat to the intake manifold.

During cruise the EGR is open, and during WOT it is closed. I am wondering if this is why you see sudden extreme drops from cruise to WOT. (Other than the air volume going up dramatically)

 

I should also note that I did remove all of the EGR equipment from the car and blocked off the ports.

Also, i posted in AMS's forum section asking for a pic of the Evo X MAT sensor since i figure they are probably one of the few people with evox motor parts lying around.

 

Keep in mind that there is a very big difference in blocking them off at the intake manifold ports, or blocking the port off inside the head. Doing it inside of the head never allows the gasses to even reach the intake manifold, which is why I did it that way.

 

How do you block it from inside the head? Is that something i can do just by removing the exhaust mani?

 

You will need to do it on the Intake Manifold side.

1/8" NPT tap with an 1/8" NPT stainless plug is what I used.

Coincidentally the EGR hole in the head is extremely close to the drill/tap size for an 1/8" NPT pipe tap. So, I didn't even run a drill into the head prior to tapping it. Literally, I just rammed the tap in until the plug sat in the hole about 0.5" below the gasket surface. (Or whenever it gets nice and tight in the hole as to not blow out. Even if it did blow out though, it will only get blown into the intake manifold. I do not see any chance of it ever possibly going into the motor.)

One thing to note though is the EGR hole is NOT perpendicular to the head. You will need to jab a pencil in there first to get an idea of the angle you need to ram the tap into the head with. Surprisingly, it worked like a charm.

FWIW, I am running 30+ psi on E85, and have been beating my new motor like crazy and it has not loosened up at all. (I have checked it 5 times since I have had it in there)

 

Interesting data, I agree, it would be very interesting to see how a car looked with the EGR and TB coolant lines disconnected along with a intake heat spacer to see if they really did anything.

On a side note, is the spike in IAT during or after the WOT pull?

As for SD setup, I think this proves one important thing. When it comes down to it, it really doesn't matter where the sensor is located. Tons of good tuners put the IAT sensor in the UICP and just as many insist it needs to go in the manifold. All of the good tuners get good tunes regardless, because the reality of it is that the motor will operate in a given situation pretty predictably and you merely tune the main fuel map and compensation tables to make it work.

Maybe the actual intake temps are somewhere between the coolant temp and the iat, but as long as your fuel table provides the pulsewidth to get the fuel you need, it will work just fine. The only difference will be that the temp compensation tables will be slightly different between the different setups.

FWIW, the biggest problem with disconnecting the waterlines on the TB is that the car will have trouble idling under certain situations. The biggest problem I ran into was after cruising on the freeway. The car would idle surge for a few minutes after getting off the freeway. I have to assume that the throttle body temp got hot enough to open/close the valve in the throttle body and would throw off the idle control valve program. I got sick of it and put the lines back on, but I never had a problem with the throttle freezing. If you block off the air passage, you should be fine doing this.