I find it usefull to think of heat flow. In all the situations of steady state described above, while temps may be constant, heat is still flowing through the metal of the IC.

Really heat soak and steady state equilibrium are two different things.

Matt

 

Dr. O said what I was trying to say, only better.

I am not here to sling *****, only science!
I feel a group hug coming on.



(They have smilies for everything!)

 

What I was describing falls under your steady state equilibrium guidelines.
I never once mentioned heat soak so to me that was never part of the discussion.
A sponge setting in a bucket of water will saturate to a particular level. It's maximum capacity under those conditions. We can call this heat soak if we chose.
A sponge in a 50mph wind tunnel cannot hold as much water. Under those conditions it's saturation point is different. This is also heat soak is it not? You can call it steady state equilibrium if you choose but it is saturated to it'sx maximum capacity under those conditions.

We seem to have a common usage term here being used as some kind of scientific term. It's inaccurate.
I used to build and QA radiators and heater coils for a living. I have a small clue. It's been a while but still, I haven't forgotten everything.
Everyone uses heat soak as if it were some magic state of badness. It isn't. It is just the maximum amount of heat an object can contain under certain conditions.

Idling in a parking lot in Antarctica in the winter. Brr f'n cold. Lets say for sh**s and grins the IC hits maybe 10ºF.

Sahara, mid day, car isn't even running. IC temp is 125º.

Is one condition under heat soak and the other not?

Is the IC in Antartica cold soaked?

 

I think the term "heat soak" is used to describe a condition where heat is negatively affecting performance..... rather than a scientific term..... a layman's example..... my car runs much better in cooler weather lets say 50F OAT than it does at 95F...... if you run your car hard at 50F and performance degrades due to a hotter and hotter charge due to the IC not being able to keep up to the point where it runs like it would at 95F OAT.......that is the condition that I think of as heat soak....simply the IC can not keep up..... now the temp changes or cooling is relative to the OAT interms of absolutes (taking into account the IC capabilities) but if you have experienced "heat soak" you know what it is..... The DFIC seems to do a very good job of staying out of this condition as long as the car is moving......

 

The whole thing is how quickly can the IC disipate the heat. It's like a radiator - heat capacity is one thing, disipation is another. In other words if a smaller unit can release the heat quicker than a larger unit, wouldn't the smaller unit be better?

 

From my experience concerning track driving/testing, the best intercooler is the one that gives you the required flow rate and lowest IATs. And that is it. I can confirm that the stocker doesn't work that well, air to water seems best suited for the street, and units like the DFIC or my "aftercooler" are the most efficient of the group.

 

Depends on the design constraints. Given no other condition, the larger device will always disspate more heat faster than a smaller unit. This, of course, assumes that both units have the sufficient flow of cooling wir for their size. There're always tradeoffs, but the most important condition is to expose as much surface area to the hot liquid/gas and as much surface area to the cooling fluid/gas as possible. The DFIC works by taking better advantage of exposing the surface area to the cooling flow than the stock or other aftermarket designs, not based on size but based on how much easier it is for the outside air to flow through the device. It's a design problem with the IC laying the way it is, not an issue of how big or small the IC is. The larger stock-type IC, like the GTT, have more surface area overall, so it's easier to transfer that heat away from the metal to the air. But there is still a flow restriction that isn't dealt with, which reduces the efficiency of the heat transfer. Does that help at all?

 

I totally agree. My apologies for not being more clear. My key word there was _if_. IF you have a more efficient smaller unit(with better airflow), then you overcome the larger unit by utilizing the air flow better. Now IF the larger unit was say, in a front mount setup, you might be more evenly matched. Again, it all comes down to how quickly the unit can expel the heat and how much it can absorb to expel. Not necessarily in that order.

 

Yes, exactly. But remember there is rarely a time when heat isn't affecting performance negatively.
At what point is it soaked? That is the question of the day.

 

Agreed.... but rather than a "clinical" explanation the question is not when it is affecting it negatively but when is that effect percieved and measured in a way that is meaningful.... ie. lap times....... calibrated instruments can measure very small increments that may not affect performance in any meaningful way.... what temperature differentials or lack there of will add 1-2-30 seconds to a lap.....

 

Since we're doing some design comparisons and Will has added a bit of info.
Let's talk about IC thickness as well. One of the design constraints on an IC is thickness. At a particular thickness efficiency goes away because you get temp stacking on the exit side of the IC. Even in an ideal flow environment the exit(back) side of an IC will be warmer than the inlet(front). To be clear I'm speaking of flow through the fins not internal induction flow.
So, given the front to back dimension of the DFIC being more than twice( at a guess) the stock IC how will (Will get it :D) this affect the temp stacking through the unit?

 

For sure. So we assume "soak" is when measurable negative affects occur?

Not just lap times. Just leaving a stoplight will do.

 

Exactly..... I threw the track reference in for Don....but more realistically for me it is the N GA and NC mountain twisties that I care about....if it doesn't matter there, I don't care.....

 

I got the track reference! We're off the Mt. Tremblant shortly for another race weekend.
Like I said before, I have the data/knowledge of the current intercooler offerings of what works and what doesn't.

 

There is a danger of heat stacking, of course, but we avoided it with the DFIC design with two things. First, there's nothing behind it to inhibit flow. Second, the ram scoop pressurizes the area in front of the DFIC. The air actually cools as it moves through the DFIC because the pressure drops from the front to the back. Add the heat that it is picking up as it moves through, and you maintain a pretty stable temperature gradient, keeping the heat stacking down pretty well. Also, the volume of air moving through the DFIC and the speed at which it flows helps significantly. It's unlikely that the performance would be as good if it were placed in front of the engine, or with some significant restrictions to the flow. As it is, the design works well.

 

Will, briefly OT here.

I asked in another thread if the m7 diverter side wings should be vertical, or left splayed (angled outwards) as they come from m7?

If they should be vertical, is there a reason why they are not shipped that way?

Sorry for the temp hijack, but the question apparently got buried and I just installed mine.

 

They should be set to form the best seal possible. I'm still waiting on mine, so I can't really help without some pictures, but having them angled out should be no problem.

 

alas, once again, there is some unsubstantiated junk science and junk engineering being touted here on NAM. if you are on the fence about what ic or scoop to buy, beware.

 

Thank you Will.

 

 

Elaborate?

 

Vertical...splayed will allow rammed air to spill out around the sides of the DFIC

 

Another "drive-by" thread shooter...

 

I guess they could be a little splayed, but the picture has it!

As long as the seal it held, it's good, but it looks as if vertical is the best bet!

Thanks, sid

 

A larger device may dissipate more heat during a particular time period but that does not mean it will reach a point of stability faster.

This is no different than quenching metal.
Fat bar, 4"x4"x10", at 1000º, thin (.5"x.5"x10") bar at 1000º. Put them in a bucket of cold water ( 25º ).
Which one would you rather pull out after 15 seconds

For arguments sake we'll assume a LARGE bucket that won't be impacted by the heat from the quenched objects.

Dimensions were exaggerated for effect. But this would be true even if we used a perforated material instead of bar stock.