00ChevyScott

iTrader: (10)

Maybe at idle sitting in traffic, but at cruising speed there should be little to no difference in IATs and ambient temps once the MAF can recover from heat soak. Also, underhood temps are influenced by exhaust manifolds/headers far more than an upper radiator hose. We're talking 400+ degree temps radiating off of 8 pieces of metal on either side of the engine bay. Ever been around a car/truck with painted headers? Those suckers put off some heat!

Also, the rear view mirror temp sensor is not the most accurate measure of ambient temps as it is mounted near the radiator (and tranny cooler if equipped/added). I have taken many logs using EFIlive and I have seen near ambient temps plenty of times as long as the weather isn't 100+ degrees outside. I have a CAI and the plate removed from the passenger side under the filter element, so plenty of fresh air gets a chance to make its way into the engine bay.

Mrgoodwrench3

Not sure where you live and what conditions you are comparing too. I am in SoCal and have many experiences traveling to Havasu, AZ. where I have seen temperatures as high as 129 degrees F !!! In extreme heat I see the ambient temperature much

higher than IAT.

I was not trying to get into a hair splitting competition here. My basic point was that coolant temp directly affects IAT. I kind of think of it like a charcoal BBQ. When you crank the arm and raise the coals closer to the meat it cooks faster and hotter. IE: hotter IAT temperature reading.

markislive78

Good debate...

I tend to think coolant temp at least marginally affects IAT's especially @ idle/park. But like 00ChevyScott & white1 mentioned a good CAI that pulls in air from the fender well or outside would be less noticeable.

white1

iTrader: (5)

And right or wrong, you are totaly entitled to your opinion. Totaly unrelated to this topic, I have met several "master mechanics" that are total idiots. Not saying that you are, just pointing out that a title doesn't make anyone the smartest person!

I am however very interested in how a thermostat that opens 15-30 degrees cooler is going to affect the temperature of the air going into the airbox, through an air filter into a MAF.

white1

iTrader: (5)

If by marginally you mean fractions of a degree, if someone were to have a CAI, I would agree. The lower thermostat would keep the engine block temperatures down a few degrees thereby lowering underhood temperatures very minimally. However we are discussing a stock engine with no other modifications. Adding ONLY a lower temp t-stat is not going to affect performance in a positive way.

As far as I understand, the way these trucks come from the factory, they are designed to run at hotter temperatures to promote more complete combustion, and minimize condensate build up in the oil.

av08

This is from log:

temp outside 107
IAT min 120 avg 131 max 153
ECT min 194 avg 200 max 208

EOT min 199 avg 219 max 230

I see IAT much higher than outside temp, stock intake

nonnieselman

iTrader: (10)

I put a stock airbox on my truck when i took the turbo off. My IATs are within 1* of what my rear view mirror shows once i get to moving.
Ive done the BB mod and besides a not so warm heater in the winter i couldnt tell a diff.
I had a k&n intake before the turbo and all it did was suck in really hot air all the time.

Now that its hot again i might put the bb thermostat back in and play with the tune some.

SLOXCAB

iTrader: (7)

Holy thread dig batman!!

nonnieselman

iTrader: (10)

im still trying to figure out how your IATs are lower than the ambient temperature.
Only way ive been able to do that was with replacing my heat exchanger with the heater core and running the AC so the Ac was chilling the water and lowering my IATs when i had the turbo setup.

I modified a stock thermostat and put it in my truck friday. Normal ECT has been 195-200*. With this thermostat the ECT has been 165-173*. But the IAT has still remained 1* from ambient.

av08

Right!, IAT will not change much! because of ECT. IAT heat source is exhaust manifold. I also monitored it on my 04 F-150 and it's the same story!!