Ambient Air temp vs Intake Manifold Air temp

["Maine"-iac]

I installed the Dashhawk and decided to monitor the air temperature difference thinking that the intercooler would in essence cool the air below ambient...not the case according to the Dashhawk. Ambient seems to be cooler than the intake manifold temperature by 2-10 degrees depending on driving speed and weather conditions. When it is raining the air temperature is about 2 degrees difference (must be the cooling effect of the rain on the intercooler) with the intake reading still being higher than ambient. On warm days the difference is around 6-10 degrees depending on how fast I drive.

Also, it has me thinking of opening up the engine bay some way (perhaps a hood scoop) to help direct air down onto the supercharger area of the engine to provide "cooling air" to the engine compartment to cut down on the amount of heat that the pipes absorb that are mounted near the supercharger itself thus decreasing the temperature difference. Has anyone else out there thought of this or have actually done it? If so, did you notice a change in temperatures at all?

[MGar]

The intercooler will never cool below ambient air temp, because that's what it's using to cool itself, and in turn, cool the air charge.

In reality, the only way to cool below ambient is to use an air to water intercooler, and pack it with ice. Even then, it will only have the possibility to cool below ambient as long as the ice water mixture remains below ambient.

[hammy221]

if you want to go below ambient you'll need to have a kit like one from Nitrous Express (NX) 20000-10 - Nitrous Express N-tercooler Systems

[GS Stage 1]

Originally Posted by MGar The intercooler will never cool below ambient air temp, because that's what it's using to cool itself, and in turn, cool the air charge. In reality, the only way to cool below ambient is to use an air to water intercooler, and pack it with ice. Even then, it will only have the possibility to cool below ambient as long as the ice water mixture remains below ambient.

Bingo, the physics of thermodynamics is a bummer.

You can always go for a cryo sprayer, but not the most practical application for a daily driver. Or does anyone make a air-water intercooler that has a built in chiller for the water? Of course then that would require another A/C style pump which would suck more power out of the engine. That would probably be counterproductive. Back to that pesky law of thermodynamics.

[P.Gadget]

Originally Posted by MGar The intercooler will never cool below ambient air temp, because that's what it's using to cool itself, and in turn, cool the air charge. In reality, the only way to cool below ambient is to use an air to water intercooler, and pack it with ice. Even then, it will only have the possibility to cool below ambient as long as the ice water mixture remains below ambient.

Second law of Thermodynamics: Heat cannot spontaneously flow from a material at lower temperature to a material at higher temperature

["Maine"-iac]

I know that you can't cool the intake air below ambient unless you are using some sort of device or liquid nitrogen or something way too inconceivable for practical purposes...just wondering if putting an air scoop in the vicinity of the supercharger might cool the engine bay down enough so that the pipes don't absorb as much heat from the engine thus heating up the intake air. I guess the best you could expect would be for the intake air temp to equal the ambient air temp. It may all be worthless to pursue such a venture as I am sure that the 10 degree difference probably doesn't make all that much of a difference in performance anyway.

[P.Gadget]

Originally Posted by "Maine"-iac I know that you can't cool the intake air below ambient unless you are using some sort of device or liquid nitrogen or something way too inconceivable for practical purposes...just wondering if putting an air scoop in the vicinity of the supercharger might cool the engine bay down enough so that the pipes don't absorb as much heat from the engine thus heating up the intake air. I guess the best you could expect would be for the intake air temp to equal the ambient air temp. It may all be worthless to pursue such a venture as I am sure that the 10 degree difference probably doesn't make all that much of a difference in performance anyway.

Approximately 1% increase in horsepower for every 10 degrees colder the intake air temperature gets.
Not a giant amount but it can add up.

[JRinKY]

"Maine"-iac : I know that you can't cool the intake air below ambient unless you are using some sort of device or liquid nitrogen or something way too inconceivable for practical purposes...just wondering if putting an air scoop in the vicinity of the supercharger might cool the engine bay down enough so that the pipes don't absorb as much heat from the engine thus heating up the intake air. I guess the best you could expect would be for the intake air temp to equal the ambient air temp. It may all be worthless to pursue such a venture as I am sure that the 10 degree difference probably doesn't make all that much of a difference in performance anyway.

We did tests with NA cars during a discussion about cold air intakes, dyno procedures, and etc. While the car is sitting still, the intake air temperature rises above ambient. How much depends on several variables, and is not consistent. One the car starts moving, however, the intake air temperature drops to within a degree or less of ambient. By 30MPH after a standing start the temperatures are essentially equal. This is with the stock intake.

The temperature rise you are seeing is due to the action of the turbo, not the heat absorbed through the pipes. he act of compressing air adds heat to it, and the intercooler is intended to remove some of that heat. As has been noted, you cannot get the hot gas (the compressed inake charge) down to the temperature of the gas (ambient air) used to cool it or even particularly close to it, as a temperature difference is needed to drive the heat transfer.

A scoop isn't going to help much, if at all.

[Critterman]

I'm running the new DDM air intake on my stage III, I see temps 2-10 degrees above ambient that fluctuate as hit the gas or let off. In traffic, sitting at a light I have seen the temp go as high as 20+ degrees above ambient. It comes right down once I start moving.

In the original version of the stage II we took IAT between the air filter and the S/C stopped at a light in the summer I would see the intake air climb to 150-160. Since the relocation the highest I have seen is 110 with ambient being 99 (stage II last summer)

WOT I have never looked, the numbers are small and it takes my eyes too long to focus, I would much rather watch the road

[MGar]

If this is about IAT temps, I am seconding what everyone else is saying, from my experience, albeit it is with a different car, but it is even further exaggerated.
'99 Camaro LS1. Stock airbox kept the IAT close to ambient while moving, and it roughly 2 minutes to rise significantly stopped. Once risen, it took till about 30mph before it reached ~ambient again.
Switch to a K&N FIPK- completely open to the engine compartment. Within 30 seconds of stopping, IAT had risen noticeably. However, it also dropped back to ambient while moving that much faster as well- roughly 20mph before back at ambient.

The whole hot engine air argument doesn't really apply, except in certain, specific scenarios- such as waiting for 20 minutes in staging lanes at a drag strip, and that increase in IAT can cause issues with launches (and launching makes or breaks your time). However, in those circumstances, even the stock airbox will heatsoak, so it's really a non issue from what I've seen.