Understanding Heatsoak

[Veracity]

Nice chart, for comparison the pre-intercooler temperature on a turbo car is usually around 250 degrees peak, but as you say the same relationships apply.

 

[CodexVelerian]

Science! Good read here complete with formulas:

http://www.gnttype.org/techarea/turbo/intercooler.html


Also, Here's an interesting chart. Even though this example is for a supercharged set-up, IMO the various temperature relationships seem to be pretty close to reality. Sized up IC's on our cars can get closer to Ambient than this though..

And I've posted this before from my old TT with lots of cooling mods Including a huge Forge front-mount:

Just read this. Nice explination on intercoolers.

However this does not explain heat soak really or how that effects the the actual cooling. When you heat soak what is actually soaking? Is it the actual air? The metal of the cooling fins in the intercooler? Is it like a spongue soaking up to much water and just cant take any more in? Heat being the water and whatever medium being the spunge.

 

[MKV727]

I think it woukd be very interesting to see....also you don't have to drill or tap into the manifold. That is one thing that always has concerned me about WMI.

I may look into this setup just to try it.

Sent from my DROID RAZR HD

You can use a TB Spacer and have no ill effects, it won't toast the throttle body either like if it would if the jet were inserted into the TB Pipe.

I personally think the best route is to do both, TB Pipe + TB Spacer. Offset the nozzles for either chemical cooling or AKI improvement and dial it in from there.

Where would the intercooler nozzle be placed?

 

[Veracity]

Another thing to keep in mind is volume, while it may be able to drop your IAT to install a HUGE core you have to pressurize the volume of the IC core and this can increase lag.

I think this concern is over stated. The size needed to create significant lag is normally beyond whats possible with typical packaging constraints. You do begin to get diminishing returns as the core gets larger in terms of improved effectiveness. I'm more concerned about adding unnecessary weight than lag.

 

[Noize]

It lowers the efficiency of the intercooler, rate of heat removal, which can increase the rate of heat soak.

You want the air traveling over the outside of the core to be as cool as possible. Under normal circumstances this would be the ambient temperature. You also want it to be moving as fast as possible. If the air travels over a condenser it will remove some heat, increasing the temp before it gets to the intercooler and the velocity will also slow down.

Heat soak occurs when the rate of energy (heat) being put into the core by the charge air (boost) is higher than the rate of the energy removed by the ambient air. As this happens the temperature of the core material increases which leads to an increase in IATs and lower performance.

This, I agree with completely and makes the most sense.
In many cars, the condensor is in front of the radiator, but behind the FMIC. Why in the heck didn't VW put the intercooler in the front? Are there retrofit kits with aftermarket FMICs that include hardware to swap places with the condensor and IC? To me, that makes so much more sense than having a small second (aftermarket) IC located down in the bumper.

Thanks everyone for the reponses and great thread!

 

[Veracity]

When you heat soak what is actually soaking? Is it the actual air? The metal of the cooling fins in the intercooler? Is it like a spongue soaking up to much water and just cant take any more in? Heat being the water and whatever medium being the spunge.

The core material is soaking up heat from the charge air thats getting added faster than its being removed.

For example if you were to do repetitive WOT runs, the core temperature will be, lets say 10 degrees above ambient the 1st time (making up numbers). Heat is added as boost passes through but its not being removed fast enough so when you start the 2nd WOT run the core temp is now 20 degrees above ambient and so on.....

The hotter the core, the lower the rate of heat transfer the higher the IAT.

 

[CodexVelerian]

The core material is soaking up heat from the charge air thats getting added faster than its being removed.

For example if you were to do repetitive WOT runs, the core temperature will be, lets say 10 degrees above ambient the 1st time (making up numbers). Heat is added as boost passes through but its not being removed fast enough so when you start the 2nd WOT run the core temp is now 20 degrees above ambient and so on.....

The hotter the core, the lower the rate of heat transfer the higher the IAT.

So it is the cooling element being saturated which leads to the air temps rising which only adds to the saturation and so forth untill no cooling can be acomplished.

 

[Veracity]

So it is the cooling element being saturated which leads to the air temps rising which only adds to the saturation and so forth untill no cooling can be acomplished.

Right except an equilibrium will be reached eventually so there will always be some cooling. All intercoolers will heat soak to a point but there will be less with an upgraded system.

 

[A_Bowers]

You can use a TB Spacer and have no ill effects, it won't toast the throttle body either like if it would if the jet were inserted into the TB Pipe.

I personally think the best route is to do both, TB Pipe + TB Spacer. Offset the nozzles for either chemical cooling or AKI improvement and dial it in from there.

Where would the intercooler nozzle be placed?

I'm just not to the point of wanting to deal with WMI.

Here is my idea for the fogger kit. Granted this is the Cry02 setup that will run you $450ish.

Source your own components and you can do it for big cheap.

Sent from my DROID RAZR HD

 

[Merkle]

It's just like a sponge absorbing water and evaporating it. There is a point at which the sponge can't evaporate the water at the same rate it absorbs it and thus becomes 'water soaked'.
Analogy over.


Back to intercoolers.
Different metals absorb heat differently. And the fins aide in dissipating the heat to the passing air. Seems simple enough. Great thread, learning a lot.

 

[Veracity]

Why in the heck didn't VW put the intercooler in the front?

I guess VW thinks most of their customers are more concerned with AC performance .

 

[GTIwannagofast]

So it is the cooling element being saturated which leads to the air temps rising which only adds to the saturation and so forth untill no cooling can be acomplished.

air temperatures will not rise between the entrance and exit of the intercooler... just not have a great change in temperature (T,enter > T,exit). complete heat soak (from what i gather) is when T,enter = T,exit.... because the intercooler temperature = T,enter. everything else up to that point is a loss in cooling effectiveness.

 

[Veracity]

complete heat soak (from what i gather) is when T,enter = T,exit....

This will never happen unless the ambient air temperature was the same as the compressor outlet , 200+ degrees. Then we'd have bigger problems

 

[bimmer635csi]

Oh the days of wet bulb temperatures, flat plate heat boundary layers, etc. etc.

Hence why IC Water sprayers are pretty effective and even foggers.

Which car company do you work for? I cant remember if I've asked you that question or not. Blue oval I'm assuming? Design or MFG?

I see grambles was able to capture more of the science than I was today. And he's an hour behind me. Yikes, maybe taking entire weeks off of work really does rot your brain.

To answer your questions though:

I'd prefer not to answer this publicly because of legal reasons. I don't want to be involved in a "Well the professional from company T said ...." kind of incident. (There might be a hint in that answer though.)

I'm neither design or manufacturing. I am an evaluation engineer for automatic transmission validation before production starts. But actually, I have a job function change starting in January, moving from evaluation to calibration. I'm looking forward to this change, and I'm one who doesn't like change.

 

[A_Bowers]

So it is the cooling element being saturated which leads to the air temps rising which only adds to the saturation and so forth untill no cooling can be acomplished.

Yes and no. Once running down the road you have air moving over the unit. Now we get to the point of the rate to which it can shed heat and the overall capacity of the system and efficiency of it.

OEM unit reaches its capacity to cool very quickly and then your intake temperature start climb rapidly as your RPM's are increasing is well

Sent from my DROID RAZR HD