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Intake Air Temperature TOO HIGH

35K views 134 replies 32 participants last post by  rcsfastgto 
#1 ·
During my data collection run last night, I recorded my IAT and it NEVER went below 109*F and got as high as 132*F. These are the numbers while the car was MOVING. My "Cold Air Intake" is anything BUT a "Cold Air Intake".

So... what to do? Go back to the stock box? Is my IAT sensor faulty? Any suggestions?
 
#2 ·
FLORIT said:
During my data collection run last night, I recorded my IAT and it NEVER went below 109*F and got as high as 132*F. These are the numbers while the car was MOVING. My "Cold Air Intake" is anything BUT a "Cold Air Intake".

So... what to do? Go back to the stock box? Is my IAT sensor faulty? Any suggestions?

Well what are the so called "normal temps"
I mean what is it with the stock box.....How do you know that is too high?
 
#3 ·
It is my understanding that the Intake Air Temperature should be near the ambient (outside) air temperature. Last night was a comfortable "high 70's" evening, so I would not expect the IAT to be 30-60*F above that. I am going to put the stock air box back on when I get home and repeat the datalogging.
 
#4 ·
Let us know

FLORIT said:
It is my understanding that the Intake Air Temperature should be near the ambient (outside) air temperature. Last night was a comfortable "high 70's" evening, so I would not expect the IAT to be 30-60*F above that. I am going to put the stock air box back on when I get home and repeat the datalogging.
I think I might have an idea if the differential is way wide...
 
#5 ·
MY IAT's with a stock box are a few degrees above ambient with the car moving, after any heat soak has dissipated. A cold car, with the ignition on, should read ambient, discounting any heating from the sun. If that's way off, your IAT sensor is probably bad, otherwise you're sucking hot air. No insult intended. An isolation box shouldn't be too hard to fabricate, using the original, possibly enlarged, cold air inlet per 1CoolPC.
 
#6 ·
FLORIT said:
During my data collection run last night, I recorded my IAT and it NEVER went below 109*F and got as high as 132*F. These are the numbers while the car was MOVING. My "Cold Air Intake" is anything BUT a "Cold Air Intake".

So... what to do? Go back to the stock box? Is my IAT sensor faulty? Any suggestions?

I was worried about this when I installed mine. I that I was told that once I was moving it would be okay but this shows it's not. Isn't it worse having the high temps than having low temps with some air restriction (stock box)???
 
#7 ·
I installed the stock air box and did two data runs; one in "city driving" with mild acceleration, and one on the highway doing between 60 and 70. NOTE: I did not start scanning until the engine was hot. It had been idling for at least five minutes. Here is a quick summary of my data:

Speed Inc. HFI
Avg ECT = 201.58*F, Avg IAT = 120.82*F, a difference of 80.76*F
Avg MAF = 3.69 lb/min
Avg MAP = 4.61 psi

Stock Box (City)
Avg ECT = 218.23*F, Avg IAT = 111.15*F, a difference of 107.08*F
Avg MAF = 2.58 lb/min
Avg MAP = 4.71 psi

Stock Box (Highway)
Avg ECT = 200.36*F, Avg IAT = 101.32*F, a difference of 99.04*F
Avg MAF = 4.39 lb/min
Avg MAP = 5.12 psi
 
#9 ·
We NEED to feed these GOATS COLD AIR! I can't believe so many people bought the warm air intakes. Its not the pipe and the filter that provide the gains, its the COLD air! On my current daily driver my air filter almost drags on the road, just to suck up the ice cold air.
 
#10 ·
In fairness to the Speed Inc. HFI kit, I need to re-collect data with the kit installed. I did not follow the same procedure for both the HFI and the stock box.

Also, using HP Tuner to examine my PCM Power Enrich tables, I found that IAT does not add anything to the Fuel Multiplier. In other words, the fuel injectors do not respond to changes in Intake Air Temperature.

The general concensus is that "more air" and "colder air" generate "more power." What I want to determine is whether the change in Manifold Air Pressure provided by the HFI is offset by the change in Intake Air Temperature. According to the tables, the IAT is insignificant to fuel control.

I always thought "rich" meant more fuel and "lean" meant more air, but from reading in this forum and the HP Tuner forum, it seems I have that reversed. Would someone please clarify this?
 
#13 ·
Rocket said:
We NEED to feed these GOATS COLD AIR! I can't believe so many people bought the warm air intakes. Its not the pipe and the filter that provide the gains, its the COLD air! On my current daily driver my air filter almost drags on the road, just to suck up the ice cold air.

At idle, you should be close to ambient assuming you are not just-starting a black car in Arizona that has been parked from 8AM-3PM on a hot August day. Keep in mind, once your car is moving over a certain speed (6-8 MPH+/-) you are truly pulling ambient air. The air traveling through your intake system is moving so fast, that it does not have time to heat up from contact with any heat-soaked intake components. However, there are pressure factors that come into play that can affect the air intake charge. Larger filtration companies (K&N) use a Computational Flow Dynamics Program to find the best combination of temperature and pressure under the hood for their intake system filter placement. Generally speaking, 10 degrees-F is equal to @ 1HP, and 1.5-lbs of pressure is equal to another @ 1HP. But again, oncd a vehicle is moving, the air temp is ambient.

If you spend some time searching teh web, you can find some interesting white papers on air flow temperature cause & effect cases. But then again, if you look long enough, you can probably find some cases against the same claims... IMHO
 
#15 ·
Well, the bottom line for me is that my IAT is nowhere NEAR ambient. Either my sensor is malfunctioning or the air is getting heated by SOMETHING. This is one of those things that will bug the daylights out of me until I find the explanation. And it is probably no big deal at all.
 
#17 ·
Extreme said:
Has anyone tried MPD CAI box w/wo ram air?

I would like to see a pic of it? I dont think they even have one on the site.
 
#19 ·
There are two issues here. One is where the air is drawn from, and the second is the concept of heat soak. They really are separate. By that I mean that a true CAI on a black car on a hot day, just idling, will read higher intake temps than the same CAI cruising down the road. I know perhaps you are saying "duh" to yourself, but, I just wanted to make that clear.

If you are drawing from under the hood, you will NEVER reach ambient. Pop the hood and actually study how cool air could possibly get through the grill and into the engine bay. It's NO straight shot! I have participated in much testing and discussion on this topic with my current car club and the fact is that the underhood area is somewhat of a pocket at any speed.

Cold air is more important than any pressure increase you can attain with an intake! If we were talking about forced induction, that's a different story, but any ram-air type effect is miniscule compared to the gains you get from the air being cold and dense.

You want an intake that draws the coldest air possible, period. Either from very low in the engine bay (could suck water, you need to be careful) or from the top of the wheel well through the fender. Is there room for this type of layout on the goat? It could be the cleanest.

Brian
 
#20 ·
FLORIT- Can you get one of those digital thermometers that has a probe? You could stick the probe within your intake and secure the display with zip ties to a windshield wiper arm or perhaps even bring it inside through the window if the wires long enough.
 
#21 ·
My last post was directed at some people either giving conflicting information or not giving information that has in the past. I would agree that cold air is what we want.

Not being able to check the temperature yet I'm relying on this forum for guidance. I have removed the stock air box and have the K&N filter on. So the question is do I spend time getting a box around the filter to improve the temp or is my current situation such that the temperature isn't much worse than the stock box.
 
#22 ·
The only way to get the filter in a better place than everyone has put it is to do some cutting into a brand new car. If you keep the same filter location and restrict the airflow to a smaller cold air source at a decent speed I think it'd be more of a restriction. Even more so on a modified motor. I understand that cold air is better... but its it really helping that much to put the filter in a restrictive box with a supply tube much smaller diameter than the rest of the induction?

The stock air box gets it's fresh airflow from under the driveside headlight, which is where these other systems get their airflow from aswell.
 
#23 ·
Experimentation

I planned all along to sheet metal brake some deflectors together to get air from the front and fenderwell on the driver's side up there. There are plenty of holes available to pass it once the stock enclosure and baffles are gone. The new fan settings for the Predator tune are becoming an issue sucking hot air through the radiator whenever the car warms up all the time. They come on and stay on. I think I either have to re-do the fan settings to stock for the stock thermostat, or lower the thermostat to 180*F and set appropriate fan temps. I am seeing big differences at idle with hood open and hood closed with all that hot air constantly blowing in there now since the tune. Once I see if restoring the fan temps helps, I might try a lower thermostat (180*F) and re-do the fan temps to see if there is additional benefit. One step at a time. I'll worry about road temps afterwards.
 
#24 ·
I will do the "hood up" and "hood down" IAT at idle experiment tonight. Thanks to my louvered hood, I doubt it will make much difference.

Old Goat, don't bother getting a 180* t-stat. Our stock t-stat is 86*C, which is about 187*F. You wouldn't be gaining much. Go with the 160* t-stat if you're going to do that at all. Remember to verify whether you have the "new style" or "old style" t-stat housing. (There's a thread on that in the "Engine" section.)

I did another data run at lunch time today. (Could not resist going home and getting the Goat.) EAC to IAT differentials are greater with the stock box, but MAP readings are lower.

Here's what I'm thinking... we all know that cold are is important and we all know that air VOLUME is important. The HFI kit gives us more volume at a higher temp. The stock box gives us lower volume at a lower temp. Chances are, it's a wash and the losses and gains cancel each other out.

What I am REALLY trying to discover here is why my IAT readings are so high to begin with. That's why I have to do this from a COLD START. (Let the engine cool down completely and check the IAT when I first start it.) The readings better be much lower until the engine warms up, or I have a IAT sensor issue.
 
#25 ·
Air Temp and volume

FLORIT said:
What I am REALLY trying to discover here is why my IAT readings are so high to begin with. That's why I have to do this from a COLD START. (Let the engine cool down completely and check the IAT when I first start it.) The readings better be much lower until the engine warms up, or I have a IAT sensor issue.
Okay, here goes. Just sat in the driveway, did hood open and hood closed long term with the Predator for measurement and Predator Tune in and here is what I found.

The STOCK fan temps are LO: On at 227*F, off again at 219*F
(per the Helms) HI: On at 235*F, off again at 227*F
Hood open and closed: Measurements not available

The PREDATOR fan temps LO: On at 190.4*F, off again at 183.2*F
HI : On at 199.3*F, off again at 190.3*F

The Predator caused the Lo fan speed to kick in precisely at planned temp, but the engine never cools below 183.2*F to turn off the fans at idle. This would occur in any event if driven faster than 30 MPH according to the Helms. I observed thermostat open occur at 180* +/- a degree or so.

Air (IAT) readings at idle, fully warmed and heat soaked for 60 total minutes at idle prior to measurements in full sunlight, ambient air temperature 74*F, minimal breeze.

Hood open, ECT stable at 192*F, fans on, IAT stabilized at 84*F...15 minutes idle observed, (30 minutes running before beginning observation to assure stabilization).

Hood closed, ECT stable at 194*F, fans on, IAT stabilized at 104*F...15 minutes idle observed after 30 minute stabilization period expired to assure heat soak before beginning observation.

These are hard numbers. I did not bother with the A/C on. I am also running the K&N filter on the Speed Induction kit, TB coolant heat stock. The tube gets uncomfortably hot right at the TB from the heat from the engine and hot air from the fans, but remains touchable. The rest of the tube stays cool. Hope this helps!
 
#26 ·
Yes, OG, that helps. Your "hood closed" readings are consistant with my observations, if maybe just a tad lower. Nevertheless, it gives me some comfort that your IAT readings were well above ambient. I don't think my sensor is bad.

Wow, what a thorough experiment! You burned a lot of gas doing that, and tortured your engine to let it idle so long. What a guy! :D
 
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