Intake Temperature

[CyberGrayRS]

We're all trying to get more air into the engine, and cooler temps, etc. While the increased airflow will reduce restriction, how important is cooler air given that the air passes through the intercooler anyway? I suppose cooler air entering the intercooler will result in that much cooler air entering the engine?

 

[SPOTWORK]

The cooler it enters the intake the cooler it will be when it enters the combustion chamber. My question is what's the best setup to get the coolest intake temps? Using an intake box, or just bareback (without a box)

 

[ecohauler]

You're not going to get cool intake temperatures with an aftermarket intake without a heat shield. The idea behind CAI is to draw colder air from outside the engine bay. The stock air box does this already, but the piping is a tad restrictive.

And regarding the original question, it matters but slightly less. The temperature of the air entering the intercooler is a function of the intake temp times the amount it's compressed (atmospheres of boost). The temperature of the air exiting the intercooler at a given vehicle speed is a function of the difference between the temperature going in minus the ambient air temp. So while warmer air entering the intercooler makes it work more efficiently, it will not achieve an output temperature as low when it's receiving warm air as when it receives cold air. How much difference there is in degrees depends on how efficient the intercooler is (which I don't know) and the ambient air temperature.

 

[sx sonic]

Well said Ecohauler!

I've had another thought on this topic that sounds logical to me but I'm not sure if it's true.
Wouldn't cooler denser air into the turbo result in a more efficient and slightly higher flowing turbo? Each gulp of the blades would have slightly more air because of the cooler air and could flow more for a given boost pressure.

any thoughts on that?

 

[ecohauler]

I've run myself around in circles trying to figure out what I think about that, sx, and the simple answer is I don't know. Colder air usually helps, so you're probably right. In terms of peak efficiency, though, I think the limiting factor for turbos is generally the mass of air they can pump, in which case denser air would just mean a slower-spinning turbo pumping the same volume of air. This might be a matter of where the bottleneck lies. If the turbo is pumping all the air that it can find, then a cooler, denser intake charge will give it more air to pump and increase power and efficiency. However, if the turbo is already at peak efficiency, I don't think you'll see noticeable gains from a cooler intake charge since ~85-95% of the temperature difference is handled by the intercooler anyway.

I may be way off on this. I have a pretty strong grasp of physics and especially thermodynamics, but I'm no expert on turbos. I'm a math major who took a few higher physics classes, not a fluid dynamics expert.

 

[XgovernmentAgent]

If anyone monitors their IAT, it is not a very accurate reading. Nothing wrong with the sensor, but the location it is reading from. Before the turbo.

The IAT sensor reads from the MAF. That isn't a very accurate reading of what the air temp is all around. You have between the turbo and the intercooler, then between the intercooler and the throttle. Knowing the latter or all three would give a better peace of mind on this subject.

 

[sx sonic]

If anyone monitors their IAT, it is not a very accurate reading. Nothing wrong with the sensor, but the location it is reading from. Before the turbo.

The IAT sensor reads from the MAF. That isn't a very accurate reading of what the air temp is all around. You have between the turbo and the intercooler, then between the intercooler and the throttle. Knowing the latter or all three would give a better peace of mind on this subject.

Indeed, no argument there

Post intercooler temps are monitored, the sensor is located in the plastic elbow before the throttle body.

Sadly we can't access the readings from that sensor. Pre was trying a workaround so the UltraGauge would read it but last I heard it wasn't working well.

 

[Preloader]

Yeah, Vince tried to tweak the ECU for to report post IC temps instead of pre-compressor temps via OBD. But it just locked up the reading to whatever the temp was at start-up.

I've kept him pretty busy with more pressing requests, so I don't want to bog him down with that additional dynamic right now. But I haven't forgotten...... It's still on my list.

Or if I felt like parting with some money, I could run my own air temp sensor to the port in my DDMW hard tube. That would give temps just before the TB, an ideal location IMO.