Is upgrading the intercooler "a thing"?

[tjbronco]

I don't understand what you're trying to say here.

This is kind of like saying "the main reason you want more money is not because of all the bills you pay - it is because more money gives you the flexibility to buy whatever you want"

No one is talking about "overheating" in terms of block temperature because your coolant isn't doing its job. Hot air makes for p!ss poor combustion. From thermodynamic law, if you compress air, it will get hot. If turbo cars didn't care about trying to keep the air temp down, they wouldn't stick a big 'radiator' between the turbo and throttle body, like they DON'T on naturally aspirated cars.

I am saying that cooler air is more dense and you can extract more power from it. For a given volume of air that you push into your cylinder, it will not be as dense with air molecules at a higher temperature. The air is more dense (for a given volume) when it is cooler. This is why you can get more power with an intercooler - over not having one. I have had turbo cars that did not have intercoolers - I have had them with intercoolers - and I have installed larger intercoolers on cars that already had them. More intercooler was always better in my experience. My point is that if the factory intercooler is not optimum (which is always a possibility), changing to a better, bigger, more efficient intercooler can provide more power under most conditions.

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[gatornek]

changing to a better, bigger, more efficient intercooler can provide more power under most conditions.

Okay. No problem. But this was the exact premise of the thread. So again, I'm not sure what you're arguing and/or disagreeing with.

 

[Mark S.]

So, a larger intercooler with less restriction, will allow the engine to work more efficiently. Even if it is not supplying significantly cooler air than the stock unit.

"Larger" and "less restriction" are not always the same thing. If you are starting out with a too-small intercooler to begin with, increasing the size CAN contribute to less restriction. At some point, however, you reach a point of diminishing returns.

The main thing you want to avoid when mucking with the intake system between the compressor and the throttle is pressure drop, because that directly affects the amount of air getting into the cylinders. Pressure drop is the difference between the air pressure leaving the compressor and that passing the throttle. For example, if you are getting 15 psi boost pressure at the throttle your turbo might be producing something like 18 psi.

Pressure drop is influenced by internal surface area and anything that affects the velocity of air movement. Things like sharp bends in pipes, too narrow passages, etc. all can restrict velocity. Internal surface area also affects pressure drop because of friction. The more internal surface area of the plumbing the air passes through (charge pipes, intercooler, etc.) the more friction it sees.

Intercooler size is a balancing act. Choose one large enough to limit restrictions without adding too much surface area.

For most modern turbocharged cars, reducing intake restriction will have little effect on power output. This is because the OEM plumbing--generally speaking--is engineered and sized to support the power demanded by the OEM software. If the OEM software cannot demand more power then changing intake flow cannot produce more power. In other words, you're already getting all the air the OEM software can use. If you want to get more power out of your engine by reducing/eliminating air flow restrictions you have to modify the software to take advantage of it.

 

[gatornek]

Have been taking various datalog trips in the mid day heat. At this point, its simply to collect other data for my possible catchcan install. I didn't bother snapping my phone for the screenshot, but the charge temp was ONE DEGREE over IAT as I pulled back into my house.

ONE. DEGREE. ....over the temperature of the air being read at the nose of the intake.

That's amazing.

Case closed. There's really nothing left to say. Yes, you can always "upgrade" your intercooler (generally just means getting a larger core, one completely made out of aluminum with welded endlinks).In fact, that's the ENTIRE PREMISE of this thread. I thought it was going to be a for sure needed thing, much like it was on my Mustang. I was wrong. It isn't.

You are wasting your time and money your if you are "upgrading your intercooler" unless you are some off road racer or some other extreme application. You don't get much better in IC performance than having your charge temp be ONLY one degree over intake. Your splitting hairs at that point.

 

[RSH]

Someone else on the board was going to upgrade the intercooler, this was for a 1.5. I didn't really follow the thread to see what the outcome was.

https://www.broncosportforum.com/forum/threads/intercooler-project.5252/#post-103048

 

[Meanderthal]

Pressure drop is influenced by internal surface area and anything that affects the velocity of air movement. Things like sharp bends in pipes, too narrow passages, etc. all can restrict velocity. Internal surface area also affects pressure drop because of friction. The more internal surface area of the plumbing the air passes through (charge pipes, intercooler, etc.) the more friction it sees.

I think that your use of “surface area” is incorrect or oversimplified. Let’s just think about an intercooler itself. The internal surface area of the intercooler is much greater (by several factors) than the charge pipe. However the restriction (pressure drop) through the intercooler, if properly sized/designed, should not be demonstrably more than a length of pipe as long as the distance from the intercooler intake/outlet. The reason for that comes down to velocity and boundary layer. This goes back to our discussion on the water on the hood. The higher the velocity through the pipe the thicker the boundary layer and the higher the restriction (pressure drop). If we just think about pipes of different diameter, a larger pipe has more surface area but has lower restriction. The reason for that is the lower velocity to move the same volume of air. That is basically what is happening in the intercooler, although much more complex. The surface area is much bigger but the velocity is much lower. The extra surface area is critical to the heat transfer side of the calculation. The lower velocity helps with both pressure drop and heat transfer.

So my original argument is that a larger intercooler will have less restriction. That larger intercooler also should have at least as good (hopefully better) internal features to have less restriction. Again that means less pressure drop from the turbo outlet to the intake valve. Less pressure drop means that the turbo is working less to deliver the requested pressure to the cylinder. Less work from the turbo is less restriction in the exhaust and that makes overall efficiency higher (more power or less fuel to achieve the same power).

 

[gatornek]

Someone else on the board was going to upgrade the intercooler, this was for a 1.5. I didn't really follow the thread to see what the outcome was.

https://www.broncosportforum.com/forum/threads/intercooler-project.5252/#post-103048

There are a handful of custom intercoolers for the 1.5. This thread was about an intercooler upgrade for the 2.0.

The deduction is: NOT NEEDED.

The IAT2 characteristics may be different on the 1.5, much like I found them to be on the 2.3.

 

[Dude]

ONE. DEGREE. ....over the temperature of the air being read at the nose of the intake

I may have miss it in your data but what was the temperature of the air at the nose of the intake ?

 

[Mark S.]

I agree that a larger intercooler CAN provide better flow characteristics, depending on the characteristics of the one you're replacing. But larger=less flow restriction is not factual in all situations.

If we just think about pipes of different diameter, a larger pipe has more surface area but has lower restriction.

An intercooler core isn't an empty pipe, it's filled with cooling fins. In the pic below hot, pressurized air coming from the compressor flows through the red area while cooling air flows through the blue area. It's not just empty space the hot air flows through.

When you increase the size of an intercooler you are not just making the air passages bigger--that would not increase cooling capacity. The whole point of a larger intercooler is to increase the amount of internal surface area exposed to hot, compressed air, because that's how you increase heat transfer. Every surface inside the intercooler the air must flow around has it's own boundary layer, that is a layer of air that is NOT moving. The more internal surface area the more volume of air that is not moving. This is why all other things being equal, a larger intercooler with have greater pressure drop. Google "intercooler size vs pressure drop" for more information.

There ARE different internal arrangements for intercoolers, and some are better than others--depending on how you define "better." Some provide for better flow (less internal surface area), while others provide for more efficient heat transfer (more internal surface area). If you have a massive turbo putting out gobs of boost and you're nowhere near the limits of the turbine output, then you can afford to lose pressure in the intercooler. The more boost the more heat, and at a certain point heat management must be prioritized over pressure loss, so you slap on the biggest, most efficient (heat transfer-wise) intercooler possible, pressure-loss be damned. But if you have an appropriately sized turbo running close to its limits producing light to moderate boost, you're better off using an intercooler that provides the necessary heat management with the LEAST pressure loss.

Here's a good article covering some of the issues surrounding intercooler fin design.

So my original argument is that a larger intercooler will have less restriction. That larger intercooler also should have at least as good (hopefully better) internal features to have less restriction. Again that means less pressure drop from the turbo outlet to the intake valve. Less pressure drop means that the turbo is working less to deliver the requested pressure to the cylinder. Less work from the turbo is less restriction in the exhaust and that makes overall efficiency higher (more power or less fuel to achieve the same power).

Given the purpose of an intercooler--to provide a surface area to make physical contact with hot, compressed air--I don't believe it's possible to INCREASE heat-transfer surface area without impacting air flow. You can certainly install a bigger intercooler with less internal surface area to affect flow, but that will adversely affect turbo lag, because all the volume must be pressurized before you can build boost pressure.

As always, engineering is a game of give and take.

 

[gatornek]

I may have miss it in your data but what was the temperature of the air at the nose of the intake ?

It’s the IAT reading. It corresponds to the sensor that clips into the air intake right where the airbox meets the tube. The “nose of the car” might be a loose description.

 

[Meanderthal]

I agree that a larger intercooler CAN provide better flow characteristics, depending on the characteristics of the one you're replacing. But larger=less flow restriction is not factual in all situations.


An intercooler core isn't an empty pipe, it's filled with cooling fins. In the pic below hot, pressurized air coming from the compressor flows through the red area while cooling air flows through the blue area. It's not just empty space the hot air flows through.

When you increase the size of an intercooler you are not just making the air passages bigger--that would not increase cooling capacity. The whole point of a larger intercooler is to increase the amount of internal surface area exposed to hot, compressed air, because that's how you increase heat transfer. Every surface inside the intercooler the air must flow around has it's own boundary layer, that is a layer of air that is NOT moving. The more internal surface area the more volume of air that is not moving. This is why all other things being equal, a larger intercooler with have greater pressure drop. Google "intercooler size vs pressure drop" for more information.

There ARE different internal arrangements for intercoolers, and some are better than others--depending on how you define "better." Some provide for better flow (less internal surface area), while others provide for more efficient heat transfer (more internal surface area). If you have a massive turbo putting out gobs of boost and you're nowhere near the limits of the turbine output, then you can afford to lose pressure in the intercooler. The more boost the more heat, and at a certain point heat management must be prioritized over pressure loss, so you slap on the biggest, most efficient (heat transfer-wise) intercooler possible, pressure-loss be damned. But if you have an appropriately sized turbo running close to its limits producing light to moderate boost, you're better off using an intercooler that provides the necessary heat management with the LEAST pressure loss.

Here's a good article covering some of the issues surrounding intercooler fin design.



Given the purpose of an intercooler--to provide a surface area to make physical contact with hot, compressed air--I don't believe it's possible to INCREASE heat-transfer surface area without impacting air flow. You can certainly install a bigger intercooler with less internal surface area to affect flow, but that will adversely affect turbo lag, because all the volume must be pressurized before you can build boost pressure.

As always, engineering is a game of give and take.

A small correction, the air in the boundary layer is flowing slower than the air in the main flow. Right at the surface the air is flowing over there is no air velocity but as you move above the surface the velocity increases essentially in a parabolic profile until the velocity is the same as the bulk air, which is the end of the boundary layer.

Let me just break this down in simple terms:

• A larger intercooler has more internal passages, which means more flow cross sectional area
• Because of that, it has slower air velocity and thus thinner boundary layer
• This is basic aerodynamics/fluid dynamics, slower flow has less pressure drop (restriction)
• So, we flow the same volume of air in the same amount of time but it is moving slower, so it has less pressure drop

Because of boundary layer effects, you can’t just compare the cross sectional area of the openings. Even if you change the shape of a round pipe, you will increase the pressure drop. So, if you were to take a round pipe and make it an oval (all while maintaining the cross sectional area) the oval would have more pressure drop. In the intercooler, there are lots of small passages. The cross sectional area of all those passages summed together would be much higher than the charge pipe cross sectional area. The larger intercooler would have even more cross sectional flow area.

A larger intercooler with more internal passages (all things construction wise being equal) cannot have more restriction. If that were the case, then a larger pipe would have more restriction than a smaller pipe at the same volume flow rate. The logic you are presenting would say that a smaller intercooler would be better for pressure loss. I just don’t see this as ever being possible.

An extreme increase in intercooler size could noticeably increase turbo lag but normal/usual increases will not have a noticeable effect. The change in volume of the overall system is generally pretty small.

We are not considering thermal effects of a larger intercooler. This thread has so far shown that the BS does not need the extra cooling of a larger intercooler.

Agreed that engineering is a game of give and take. It’s just not true that a larger intercooler will have more restriction. There are other reasons why the engineers didn’t put a larger intercooler on the BS. Could be cost, or available space, or maybe it is just that it is big enough to cool the intake air within a couple of degrees of ambient. It was not done to decrease the pressure drop across the intercooler.

 

[Mark S.]

It’s just not true that a larger intercooler will have more restriction.

I think we're talking past each other again. I'm not saying this is true in ALL cases. This article does a better job of explaining what I mean.

 

[Meanderthal]

I think we're talking past each other again. I'm not saying this is true in ALL cases. This article does a better job of explaining what I mean.

Okay, so maybe my description of the intercooler as “bigger” needs some qualifiers. To me, bigger would mean more internal cross sectional area. However, it would be possible to produce an intercooler that had the same internal cross sectional area but longer flow paths. This would technically be a larger intercooler that has more pressure drop than the stock intercooler. I don’t think I have ever seen an upgraded intercooler that wasn’t thicker than the stock unit but it could be done if there is room for a wider intercooler. The increase in thickness leads to an increase in internal cross sectional area.

I think these 2 paragraphs from the article cover the topic relatively well:

Internal area affects pressure drop because as area increases, so does the available contact surface for the airflow. As discussed above, this puts the flowing air in intimate contact with more intercooler, which removes energy from the air. Air likes to attach itself to walls (or really anything that it’s flowing relative to) and this is called the boundary layer. The boundary layer is a theoretical point of zero velocity, and represents a flow loss to the air passing adjacent to it. When the total surface area of the boundary layer grows, energy is removed from the air, and the total pressure loss grows as well. So, this is just one reason why “bigger” isn't always “better”!​

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On the other hand, increasing the size of an intercooler can also reduce the resulting pressure drop. The velocity of the air passing through the inside of the core is a function of the volume of air flowing and the passage cross-sectional area, and fluid friction is a function of velocity. So, if the cross sectional area increases and airflow velocity drops; then so does the friction generated and the resulting pressure drop. So there's definitely a balancing act one has to play when sizing an intercooler core for a specific application. If the internal cross-sectional area of an intercooler is fixed, then increasing the airflow (by turning up boost, or revving higher for instance) will increase velocity, which increases the associated pressure drop. Let’s look at some charts to see how this actually holds in practice.​

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There’s some simplification there but in general the concepts are relatively well represented.

 

[Mark S.]

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There’s some simplification there but in general the concepts are relatively well represented.

Agreed. Bottom line: A larger intercooler CAN reduce pressure loss, but not always.

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