Aftermarket intercooler or OEM

mass-hole · **Posted:** Wed Apr 27, 2016 10:51 pm

Here is what my stock F150 CAC does. It was a standing start and I pulled to the top of 3rd gear or about 100mph climbing a hill. I thought the truck had a temp sensor between the turbos and CAC but it does not, only an intake air temp and Manifold temp. My guess is the pre-CAC temps were 80-90C.

I think the temp drops initially as the truck starts moving and air starts to blow over the CAC then it is overcome and the temp starts to rise even though the truck is then moving at close to 100 mph by the end of the pull.

From what I have seen with the aftermarket CAC''s for the F150, they actaully reduce temps as the speed increases.

Here is what another guy saw stock and aftermarket CAC

Stock:

Aftermarket:

This image shows to two CAC's:

I think this is even more important for us since we consistently run higher boost pressure even during steady state cruise conditions.

mass-hole · **Posted:** Thu Apr 28, 2016 7:35 pm

Auberon wrote:

Just a quick response.
That was harsh and unesecesarily critical of a long-term observation of real-world information.
I will just not waste the time and share real numbers I have observed over a long period.
I actually don't have the time to waste on the unappreciative anyway.
I am at the point where the negativity of most just wants me to keep more and more to myself especially when people don;t read what I have actually written and then jump.

I used the the same formula catcrd used. Where does it say you have to have false running conditions?I did note this.

WHOA!
I mention Relative Humidity because it has much to do with the ability of air to carry heat with it.
This system has a high entropy (the bit which doesn't do work) Unfortunately it should be high.
Thus RH is highly relevant in terms of heat exchange ability of external cooling air.

The MAP is superfluous when measuring temperature IN THIS CASE. Yes, it influences combustion control but where/how does THIS system measure aftercooler efficiency? That is a separate issue. This engine is scant on sensors at best.

MAP temp sensing is irrelevant other than for controlling factors beyond those we are writing of. Please don't give them more cred than they deserve. but by the same token RH does influence manifild absolute PRESSURE by affecting the density of the air.
MAP runs the engine - not measures the efficiency of the aftercooler.

I thought the issue was;
How would the system perform with a more efficient heat exchanger????

Why not look at real world situations? rhetorical.....
Rhetorically (cos I don't give a rats about the answer) is it being suggested I drive around in utterly sweltering temperatures (constantly) to appease some.
Until complete methodolgoy and engine loading etc is standardised other than an approximation of grade this is a pointless jab. At least I had real world engine loads. This cannot be replicated unless RH and the other misunderstood factors are stated with a degree of certainty. I at least measured these environmental parameters which do affect the system.

I again draw attention to the fact that this is a long-term (for some 6 years) observation of the inefficient operation of this aftercooler.
-Initially based this on Performance How-To Turbo. Real World High Performance Turbocharger Systems by Jay K Miller.-
ISBN-13 978-1-932494-29-7
For now, simple fact is that temp IN often is NOT sufficiently /significantly less than temp out in the CAC for normal everyday benefit which suggests that in REAL WORLD running it is an inefficient unit.
Therefore, the heat exchange efficiency of the unit is POOR.

I have watched this behaviour constantly for 6 years. It doesn't change.
This aftercooler is consistently POOR at creating a TEMPERATURE DIFFERENTIAL (in the right direction) that my reading from fact checked texts tells me is acceptable.

The CAC is (again read from the source above which is a nice basic presentation) without even mentioning the Laws of Chemical Thermodynamics.
Air is a complex thing and clearly misunderstood.
It took thousands of years to even get to Boyles law let alone the more sublime nuances of its behaviours.
It is a study in its own right.

WHY Relative Humidity (RH)?
Its behaviour is governed by P, T and mass. It has nothing to do with dealing with a wet surface.
It is to do with heat capacity.
100% saturated air (common where I live) has Specific Heat (Cp) of 2000 Joules / Kg deg K
and cold air by the same token has Cp = 1020 Joules /kg deg K
In other words:

The mean molecular weight of dry air is approximately 28.97.

The molecular weight of water is only 18.

This means that volume by volume, moist air is lighter than dry air.

The amount of energy required to heat up dry air is less than the amount to heat up the same volume of wet air. This is because of the difference in Specific Heat between dry air and water vapour.

Everything has a Specific Heat. This is the amount of energy that is required to heat up a given mass of stuff compared to the amount of energy required to heat up the same mass of pure water. If we keep the pressure the same, the Specific Heat is termed Cp.

Cp for 100% water saturated air at atmospheric pressure is about 2000 Joules/kg deg K (or 2.00 kJ/kg deg K)

Cp for dry air at atmospheric pressure is 1020 Joules/kg deg K (or 1.02 kJ/kg deg K)

Integral to the CAC design is a trade off between the heat exchanged within the unit and radiated to the outside environment (hence, the mention of turbulators). All engineering is a trade-off when it comes to heat exchange.
I would also suggest some folk look at the behaviour of non-ideal gases.

The fundamental premise that is being missed is that turbulators increase the density of the air exiting the Aftercooler. Therefore they have the potential to increase efficiency. This is, afterall, the primary function of an aftercooler is to further increase the density of air after the turbocharger has done its work. (Miller). Again per Miller the gas laws dictate a loss of 1 to 2 lbs across the aftercooler.

Quote (Miller)....which I happen to agree with by qualifications....."An aftercooler, by its very nature tends to be somewhat of an engineering dichotomy. It is both a pressure vessel and a heat exchanger.

Miller then runs into a rather useful description of available designs that are best suited for boost of around 20psi...which I again concur with. For the unitiated he describes the difficulties in encountering laminar flow in an aftercooler and how (loosely) it introduces certain ineffiencies of design of heat exchangers and then reviews (convincingly) the gains of turbulators. The mistake being made is that efficient flow with little resistance is the absolute goal. Fact: without contact with the metallic interface with the outside air ram there is minimal heat exchanged.
Air is not an ideal gas since it is not pure.

Seems to me some very basic engineering and physics needs to be better understood before I get shot at and some credibility assumed for long-term as opposed to short term observations.

That is all I have to say on the matter.

I am curious how RH affects the heat exchange process if the air flowing inside(intake) of the heat exchanger and outside(ambient) are from the same source. In our jeeps(and all cars) the intake air and the cooling air are the same. If the outside air is 30C and 100% RH then what happens during the compression in the turbo. You heat the air to say 150C, which would allow it to have a higher absolute humidity, but you have also compressed it to 2.3x the density. Does the density lower the absolute humidity and is it enough to condense water out? If the density change alone is not enough then would it occur during the cooling in the CAC? If it does condense out does this add or subtract heat from the system.

funnyman06 · **Joined:** Sun Jul 06, 2014 7:46 pm **Posts:** 180

I dont believe pressure has much to do with the relative humidity of the air. I think you'd look at the temps in and the temps out and then you could tell whats going on. The only way i could think you would actually cause the air to condensate would be to drop your charge temp below dew point. Which isn't gonna happen.

diesel_guy86 · **Posted:** Thu Apr 28, 2016 9:37 pm

My machines hydraulic oil runs cooler on humid 95° ohio days than they do in dry 95° lone pine, California days.

flash7210 · **Posted:** Fri Apr 29, 2016 8:45 am

diesel_guy86 wrote:

My machines hydraulic oil runs cooler on humid 95° ohio days than they do in dry 95° lone pine, California days.

I'm not an engineer, so I dont fully understand all the properties of air-to-air and liquid-to-air heat exchangers and how humidity effects those properties...

But I can safely say that my personal humanoid organic liquid-to-air heat exchanger (which in my opinion has a larger than average surface area) "feels" cooler at a dry 95F in Phoenix AZ than it does at a humid 95F in Jacksonville FL.

flash7210 · **Posted:** Fri Apr 29, 2016 8:56 am

I think that regardless of ambient temperatures and humidity, the most important factors in heat exchangers (both air-to-air and liquid-to-air) are surface area and air flow.

BTW, all this discussion about intercoolers and nobody has mentioned liquid-to-air intercoolers.
(or are they called after-coolers?)

mass-hole · **Posted:** Fri Apr 29, 2016 9:42 am

diesel_guy86 wrote:

My machines hydraulic oil runs cooler on humid 95° ohio days than they do in dry 95° lone pine, California days.

That makes sense to me since the hydraulic fluid doesn't change but the air does. In the Jeep, if the air blowing over the cac changes, so does the air inside since the are both from the same place.

WWDiesel · **Posted:** Sat Apr 30, 2016 1:46 pm

What I remember from my Power Plant days and thermodynamics training: The humidity of the air passing either over the fins or through the insides of CAC has a huge bearing on how efficiently the air can absorb or give up BTU's. Normally more humid air would be much more dense (heavy) and a much better heat conductor than thinner drier air. Thus humid air would be more efficient at absorbing BTU's on the outside of the CAC and also better at giving up BTU's on the inside of the CAC... Ever notice that when driving in the rain, turbo charged vehicles seems to have a little more power? Gas engines run better as well since the humid air entering the intake is denser..
They even sell mist systems that mount in front of radiators to help cooling efficiency by producing a higher density cooling air flowing through the heat exchangers.
As Flash stated, a water to air heat exchanger is a much more efficient heat exchanger and does not require near as much surface area to produce the same given results.... :wink:

diesel_guy86 · **Posted:** Sat Apr 30, 2016 2:53 pm

flash7210 wrote:

I think that regardless of ambient temperatures and humidity, the most important factors in heat exchangers (both air-to-air and liquid-to-air) are surface area and air flow.

BTW, all this discussion about intercoolers and nobody has mentioned liquid-to-air intercoolers.
(or are they called after-coolers?)

Liquid to air are great, but require another small radiator to cool the intercooler water, as well as a waterpump to circulate. Our engine bay are already cramped. I had the idea of putting another a/c condensor in the intercooler watertank to "supercool" it, but it came down to being way more work than what i would gain.

I still think we need to move away from the tall and thin ic, and move towards a thicker more compact unit. This would also free up some frontal area for the radiator. As of now the ic pre-heats the air in front of the radiator, leaving less temp differential needed for cooling. That should speak volumes of our cooling system, we stay cool even with a 150°+f charge air cooler in front of it.

flash7210 · **Posted:** Sat Apr 30, 2016 6:08 pm

So many great ideas, so little room under the hood.

The problem with the liquid intercooler is not the extra (and smaller) radiator it requires, but where to put the cooler itself.
The barrel type coolers are 4 inches in diameter and 12-18 inches long. One "might" fit on top of the fan shroud. Seems like the best place for it.
The box type coolers come in various shapes and are usually 3.5-4.5 inches thick. One "might" fit on top of the engine. I see no other place where it could go.

I really like the idea of the liquid intercooler. Seems like the best bang for the buck and eliminates all questions about cooling and flow efficiency.
The question is, do I really want to cut a hole in my hood to make it all fit?

The advantages of the liquid intercooler:
1. Better cooling
2. Less boost pressure drop
3. Is not dependent on forward motion for good cooling (cools just as good when crawling at slow speed)

The disadvantages:
1. Where to mount the cooler?
2. More weight
3. Electric water pump required
4. More liquids and places for leaks

mass-hole · **Posted:** Wed Aug 31, 2016 12:00 pm

I just wanted to report back that I am seeing CAC efficiency in the 65-70% range on average with TorquePro logs and some hand calcs. I did a 3rd gear pull from 1700 to 4000 rpm(40 to 100 mph so plenty of airflow) and I assume a turbo compressor efficiency of 70% for outlet temps. It seems that the CAC is starting to heat soak by the end of my pulls and efficiency starts to drop sharply, like towards 60% or lower. so I would imagine extended high throttle pulls, such as towing a trailer, could result in extremely poor CAC efficiency once it gets hot.

My guess is half the problem is that the CAC sits behind the A/C condenser blocking most of the airflow.

flash7210 · **Posted:** Wed Aug 31, 2016 1:49 pm

Where are you taking your temp readings?
Both pre and post CAC?
And what actual temps were you seeing?

I can only read IAT from the TMAP with torquepro.
On a 90 deg day, my IAT is about 120 with Ac-off.
With AC-on, IAT is can be 130-140F.

Heat soak is a problem, especially with the sensor being mounted on top of the engine.
After being parked for 20 min and then starting it back up again, I've seen IAT as high as 156. And that was with the AC off. At that point, the TMAP is a top of the engine temp sensor.
After about 30 min of driving with the AC on it finally dropped below 150.

Lets face it, its been a hot summer. And if you want to be comfortable the AC must be on. So your IAT and engine performance is gonna suffer.
And your radiator and cooling fans better be in good shape, otherwise... :dead:

mass-hole · **Posted:** Wed Aug 31, 2016 2:17 pm

flash7210 wrote:

Where are you taking your temp readings?
Both pre and post CAC?
And what actual temps were you seeing?

I can only read IAT from the TMAP with torquepro.
On a 90 deg day, my IAT is about 120 with Ac-off.
With AC-on, IAT is can be 130-140F.

Heat soak is a problem, especially with the sensor being mounted on top of the engine.
After being parked for 20 min and then starting it back up again, I've seen IAT as high as 156. And that was with the AC off. At that point, the TMAP is a top of the engine temp sensor.
After about 30 min of driving with the AC on it finally dropped below 150.

Lets face it, its been a hot summer. And if you want to be comfortable the AC must be on. So your IAT and engine performance is gonna suffer.
And your radiator and cooling fans better be in good shape, otherwise... :dead:

Turbo outlet temps are calculated based on pressure ratio and compressor efficiency which is in the 70-72% range. The true temperatures are likely not too far off. It's not like the calcs would be so far off that the intercooler is really 90% efficiency. To get a 150F IAT with a 90% efficient CAC on an 80F day means the pre-cac temp would need to be like 900F which obviously is not the case. The only thing that might throw it a bit off is if the pressure drop across the intercooler was huge, but whether or not its just poor efficiency or big pressure drops, the performance is still not great and the IATs are high. I have seen 160F with the A/C off and 180F+ with the A/C on. Thats bad.

By heat soak I meant the CAC heat soaking. It's "cold" at first but the longer you run it at high boost the more heat it absorbs from the air charge. It doesn't expell enough heat to the cooling air so it warms up which makes the temperature delta between the intercooler material and the charge air smaller which lowers the efficiency even more. My guess is if you towed a heavy trailer up a long hill at full throttle, you would see IAT's in the 200F+ range once the CAC fully soaked and reached steady state.

Ideally the CAC would be big enough and flow enough cooling air that its able to dump as much heat as it needs to without much of a temperature rise, that way it maintains efficiency for extended high loads. If we can improve CAC efficiency from 70 to 90% that would give us a 12% increase in mass air flow meaning cooler EGT's, cleaner burn, and more power with more fuel all without touching boost.

Sent from my Nexus 6 using Tapatalk

flash7210 · **Posted:** Wed Aug 31, 2016 7:07 pm

So what are you estimating CAC inlet temps to be?
About 400F ?

mass-hole · **Posted:** Wed Aug 31, 2016 9:44 pm

flash7210 wrote:

So what are you estimating CAC inlet temps to be?
About 400F ?

325F based on some runs i did with the GDE Hot Tune. Peak pressure ratio is 2.63:1 here at 6500' and I assumed 70% compressor efficiency.

Edit: CATCRD recorded 314 on a pull up a 10% grade with 66F ambient temps, so that would put it right around 325F if temps were in the 80's. He also calculated a 67% efficiency so I am pretty confident in my calculations.

I may try to snag some thermocouples while I am back at my company headquarters next week so I can actually get really temps pre and post CAC.

Aftermarket intercooler or OEM

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