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Why Intake Air Temperatures Can’t Be Compared Between Positive Displacement and Centrifugal Superchargers
 

Abbreviations/Acronyms/Definitions in This Article:

- The words Blower and Supercharger are interchangeable.
- Centri = Centrifugal
- PD = Positive Displacement. This includes roots, roots improved, TVS and Twin Screw blowers.
- IAT1 = Intake Air Temperature before the blower.
- IAT2 = Intake Air Temperature after the blower and after the intercooler.
- IAT = Unless noted otherwise, I’ll be using IAT interchangeably with IAT2. It’s the IAT that really matters, and in a lot of cases the only one you know.
- DT = Blower discharge temp. This is what the temperature of the air is after it comes out of the blower and before it passes through the intercooler. This temp is rarely sampled in anything short of a full bore race car.
- IC = Intercooler.
- A2W = Air to Water. This is a type of intercooler system. All PD blowers come with these if they have an IC at all.
- A2A = Air to Air. This is the other type of intercooler system. Most Centri blowers come with an A2A. But a few come with A2W systems.
- Ambient or ambient temp = Outside air temp.
- Air charge = The compressed/heated air after the blower.
- Charge Air Cooler (CAC).
- Low Temp Radiator (LTR).
- Mass airflow sensor (MAF).
- WOT = Wide Open Throttle
- TB = Throttle Body

A few words on intercooler system/parts names/definitions/descriptions/and confusing stuff.

In different segments of the automotive world, some components are called different things but they’re exactly the same. The OEMs call one thing “A,” while the aftermarket calls the same part “B.” And the Ford crowd may call it “C.” And the tuner crowd can call it “D.” So, obviously, this can get confusing. I’ll clear that up here. Well, clear it up for this article. I won’t be fixing the internet!

In the “Mustang World” and This Article, You’ll See These Words Used for These Things:

-Intercooler. This is the cooler that sits in the intake manifold under the blower on PD blown cars.

-Intercooler. This is the cooler that sits behind the bumper cover and in front of the radiator/air conditioning condenser on A2A Centri blown cars.

-Intercooler. This is the cooler that sits in the “box,” usually in the engine compartment the air charge is run through on A2W Centri blown cars.

Confusing huh? Three different “intercoolers.”

-Heat Exchanger. This is the cooler that sits behind the bumper cover and in front of the radiator/air conditioning condenser on PD blown cars.

-Heat Exchanger. This is the cooler that sits behind the bumper cover and in front of the radiator/air conditioning condenser on A2W Centri blown cars.

In the World of OEM Manufacturers, You’ll See These Words Used for These Things:

-Charge Air Cooler (CAC). This is the cooler that sits in the intake manifold under the blower on PD blown cars.

-Charge Air Cooler (CAC). This is the cooler that sits behind the bumper cover and in front of the radiator/air conditioning condenser on A2A Centri blown cars. But there are no OEM blown Centri blown cars, so really you’ll only see this from the OEMs when describing turbo setups.

-Low Temp Radiator (LTR). This is the cooler that sits behind the bumper cover and in front of the radiator/air conditioning condenser on PD blown cars.

And One More:

Technically all of the intercoolers, heat exchangers, LTRs, CACs, etc. are……………..heat exchangers.

As you can see, it doesn’t take much for confusion to ensue. I’ll be using “Mustang World” terminology in this article.

“Centri Blowers Have Lower Intake Air Temps than PD Blowers Do!”

“Centri Blowers Run Cooler than PD Blowers Do!”

“Centri Blowers Don’t Heat Soak Like PD Blowers Do!”

 

I see the above quotes (and more like them) all the time. Someone will say something along the lines of “Centri blowers have lower IATs than PD blowers do.” That statement, in some cases, is true. But in other cases, it’s completely false. And there’s a 99.9% chance that people making that statement have no clue what they’re actually talking about. They’re probably repeating what others said. And that person didn’t know what they were talking about either. They’re making the blanket statement that Centri blowers always have lower IAT2s than PD blowers do, and that couldn’t be any more wrong. It’s a fairly complicated situation to understand, and most people, even people in the go fast parts industry (especially retailers and dyno operators/tuners), don’t possess the information to make statements like the above. So, to sum up, when you hear people making the above statements, you can be almost certain that they’re talking from a position of ignorance.

 

Some Basics

To fully understand why you can’t make blanket statements like “Centri Blowers Have Lower Intake Air Temps than PD Blowers Do!” you’re going to need a good understanding of a few things. Here they are:

 

Why You Have An Intercooler

Compressing air (boost) creates heat. Heat at a certain point causes detonation in the motor. Detonation is when the fuel’s octane can’t cope with the heat being generated. This results in cracked rings, cracked pistons, melted pistons, broken connecting rods and sometimes even cracked engine blocks. Detonation and temperature control is obviously a huge thing. You can turn a motor to scrap in a matter of a second if your IAT’s are too high.

Thankfully in the modern age the engine management systems (ECU/ECM/Computer/whatever you call it) are incredibly good and have all sorts of fail safes built in. In most cases if your IAT’s are too high you won’t turn your motor to scrap. The ECU will know that the IAT’s are too high and in turn will retard the ignition timing dramatically to keep everything in one piece. The penalty for that is a massive loss in horsepower though. It is not uncommon for a 500hp car to lose 100hp. I’ve seen 600-800hp cars loose 250hp when IAT’s aren’t kept in check. So, you may not blow motors up when IAT’s get out of hand like in the old days. But you do pay a huge HP penalty.

Most tuners (and OEM’s) want IAT’s below 135degF and set the ECU to pull timing at anything over that number. If you’re running e85 or good race fuel you can push that number up some. But that doesn’t apply to most people.

What’s the Difference between an Air to Air and Air to Water Intercooler System?

You’ll find two types of intercooler systems in most applications. Air to Air (A2A) and Air to Water (A2W). All PD blower systems use A2W IC systems. Most Centri blowers use A2A IC systems. But a few Centri blowers do use A2W.

Air to Air

A2A systems are fairly simple. The blower discharge air is run through an A2A IC that sits up behind the bumper cover and in front of the radiator. The hot air from the blower goes through the IC (inside) while the cooler ambient air is moved across/through it (outside). The temperature difference between the inside and outside of the IC cools the air charge. The air charge is then piped into the motor/TB/intake manifold—a very simple system with no moving parts.

Here is a picture of one. The red arrow is pointing to the intercooler. The green arrows are the piping that’s feeding the air from the blower to the intercooler and then the cooled air to the TB/intake/motor.

Air to Air Intercooler

Air to Water

A2W systems are quite a bit more complicated than A2A systems. Because PD blowers sit on top of the motor, it doesn’t leave enough room to run a 3”+ pipe out to an A2A IC and a 3”+ pipe back in. That would be a MESS even if you got it to work. So, PD blowers have the intercooler inside the intake manifold under the blower discharge port. Well, some are blowing “up” into an intercooler. But you get the point, the blower blows air directly through the intercooler.

Here’s a picture of an intercooler (blower removed).

Air to Water Intercooler

Water is pumped through the intercooler, which is then pumped out to the heat exchanger, which is located behind the bumper cover/in front of the radiator (pictured here).

Air To Water Heat Exchanger

Compressing Air

When air is compressed, it heats up. In a perfect laboratory environment with a 100% thermal efficiency, compressing air to 1psi will raise its temperature 9.89deg (all temp measurements are in Fahrenheit). But, that’s in a perfect environment. Superchargers are not a perfect environment. They have some inefficiency when it comes to compressing air. Some more than others. And different blower speeds will result in an even greater variation. It can get confusing, so here are a few “data points” to consider/put in your memory banks:

- Twin Screw blowers are the most thermally efficient of the blowers. This is because they’re actual compressors where everything else is a “blower” to one degree or another. You’ll see about 12deg/psi of temp gain with a Twin Screw.

- TVS blowers are almost as good as a Twin Screw when it comes to thermal efficiency. Eaton has done a hell of a job making a Roots Improved blower (which is what a TVS really is) act like a Twin Screw. With a TVS you’ll see about 13deg/psi of temp gain.

- Centri blowers are not quite as thermally efficient as the Twin Screw and TVS blowers. They clock in at about 13.5deg/psi of temp gain.

- Roots Improved blowers are the least thermally efficient “popular” blowers out there at about 14deg/psi of temp gain.

- A true Roots blower (think old school blower with carbs on top) is the least thermally efficient at 16-20deg/psi of temp gain. You don’t see these much anymore though.

But Wait, There’s More.

- If you put a blower on that’s too small for the HP level that you’re trying to run at, you’ll have to spin it faster. Which will push it out of its thermal efficiency range. And the closer you get to the maximum RPM, the more heat they’ll make (it’s exponential). For example, a properly sized Roots Improved blower can have lower discharge temps than a Twin Screw that’s too small for the job.

- If the blower has an inlet restriction—like the elbow is too small (which you usually can’t improve), the throttle body is too small, or the cold air intake is too small—you’ll have to spin the blower faster than one that has properly sized inlet components. This is another case where a Roots Improved blower can have lower discharger temps than a Twin Screw.

So How Much Heat Are We Talking About Here?

- A correctly sized Twin Screw making 10psi will get you a temp rise of about 120deg. But then you have to add that to the outside air temp (ambient), which we’ll say is 80deg. That is a total discharge temp of 200deg.

- A correctly sized Centri making 10psi will get you a temp rise of about 135deg. Then add 80deg ambient, and you have 215deg. Not a massive difference. But when your goal is to have a maximum IAT2 of 135deg, the extra 15deg the centri is making represents are fairly large percentage.

Now let’s turn up the boost.

- A correctly sized Twin Screw making 15psi will get you a temp rise of about 180deg. Then add the ambient temp, which is 80deg. That’s a total discharge temp of 260deg.

- A correctly sized Centri making 15psi will get you a temp rise of about 202.5deg. Then add 80deg ambient, and you have a 282.5deg discharge temp.

At this point, the “out of the box” intercooler systems are struggling to keep IAT2s below 135deg (some won’t even be able to). That extra 22.5deg of discharge temp from the Centri is absolutely making a difference.

Now let’s turn the boost up one more time.

- A correctly sized Twin Screw making 20psi will get you a temp rise of about 240deg. Then add the ambient temp, which is 80deg. That’s a total discharge temp of 320deg.

- A correctly sized Centri making 20psi will get you a temp rise of about 270deg. Then add 80deg ambient, and you have a 350deg discharge temp.

At this point, we’re talking about some serious heat. There isn’t an “out of the box”  intercooler system that will keep these sorts of temps down to a safe level (under 135deg). You would be hard pressed to build a custom A2W that can keep up. And you will never get an A2A that will get the job done.

Heat Transfer – Transfer Medium

Water transfers heat 24.17 times faster than air. Let that sink in. The water in an A2W system will transfer heat 24.17x faster than the air in a A2A system.

Water transfers heat 24.17x faster because it’s more molecularly dense. That means there’s more “stuff” to whisk the heat away. It also means that, for a given volume, let’s say a cubic foot, there’s more “storage” capacity to “store” that heat. Sounds like a clear winner, right? Give me an A2W setup any day! Well, just like most things in life, there are flip sides and “in this cases”…. Keep reading.

The Intake Air Temp Sensors Aren’t the Same

Right here is where the biggest confusion about IATs between PD and Centri blowers comes from. They don’t use the same kind of sensors. And they act wildly different, and they don’t give comparable data.

PD blowers have what I call a “bulb style” sensor. They react to temperature changes immediately. This is why you see the OEMs using them for their blower applications. They all use basically the same sensor. And the aftermarket uses OEM sensors in their kits. They’re instantaneous, accurate, inexpensive and reliable. Here’s a picture of one.

“Bulb” Style Sensor

Centri blowers “re-purpose” the car’s stock IAT sensor that’s built into the mass airflow sensor (MAF). They can do this because, unlike a PD blower, a Centri unit is blowing through the MAF with boost pressure (the MAF is before the blower on a PD setup so it “sucks” through the MAF). There’s a problem with using the IAT sensor built into the MAF though. It was never designed to deal with a blower application. The IAT sensor in the stock MAF was designed to measure air temps going into the motor that weren’t under boost. That means the sensor wasn’t designed to react quickly or to deal with really high spikes in temperature. It doesn’t need to when used as intended. In a naturally aspirated use, it will never see the extreme fluctuations that a boosted application will.

What’s the net result of using an IAT sensor that wasn’t designed for blower applications? Well, it’s problematic and not accurate at all.

The biggest issue is that the IAT sensor can’t “keep up” with radical temperature changes (going into boost). So, what you get is incorrect data. It takes the IAT sensors built into MAF sensors about 8sec to stabilize or “catch up.” Here’s an example of what happens:

You’re cruising down the road at normal speeds and not in boost. Your IAT temps are effectively ambient, let’s say 75deg. Your car makes 10lb of boost at WOT, which is an additional 135deg (roughly), which gets you a discharge temp of about 210deg.

Now you whack the throttle wide open. Unlike the bulb style IAT sensor used with PD blowers, the MAF IAT sensor can’t keep up with that temperature change. A tuner friend did a test to show how long it takes for the IAT sensor to stabilize and actually show you the correct IAT temperature. He did this for himself, but he posted the results to help educate the public. Here’s what he found out.

It took 7.88sec for the IAT sensor to read the actual intake air temp of 142deg. The rate at which the sensor “caught up” wasn’t linear (graph below). There’s a curve to it. That means, when you first go WOT, the sensor is WAY behind. Only as time elapses does it start to catch up faster. What does this mean in the real world?

- Unless you’re WOT for more than at least 7.87sec, you don’t know what your actual IAT is. 7.87sec seems like a lot, but it’s not. Dyno runs aren’t nearly that long—usually about 4sec. So, showing an IAT the car made on the dyno is useless. 7.87sec is going to be over a 1/8mi run at the drag strip. So, if you run a 1/8 mile, you won’t see your true IATs. 7.87sec is actually a pretty long pull on the street. Most of the time, you’ll never see the actual IAT. And, every time you shift, there will be a slight pause in boost. Which means a temp drop. You most likely aren’t restarting the clock, but it has to have some sort of cooling effect on the IAT sensor, which will trip up a true reading even more.

-The graph is only showing discharge/IATs for about 8psi. What happens when it’s 15psi and the temps go way up? Does it take longer for the sensor to catch up? Does the curve look different? It’s possible. I don’t have any data to base a conclusion on though. That said, it’s entirely possible that, when the boost goes up, the disparity between actual IATs and what the sensor is telling you gets larger for longer.

-A point that has nothing to do with this article, but it’s a point that should be known. If you’re running 15lb of boost with a discharge temp of 275ish deg and you’re past where the A2A IC can keep up, what are your actual IATs? The sensor isn’t telling you what they are for 8+ sec (it could take longer with higher temps). How often are you doing logging/testing that will give you a true IAT? It’s not on the dyno. It’s not in the 1/8mi. It may not be in the 1/4mi. And it’s rare that’s going to happen on the street. So how do you know that you don’t have a 200deg IAT, which could cause detonation and a blown up motor? If I had a Centri car, I would be using a bulb style IAT sensor in the intake manifold.

IAT Sensor Location

There’s another issue with comparing A2A to A2W intercooler systems. And, in most cases, that means Centri vs PD blowers. And that is sensor location. This location situation has a lot to do with what’s commonly referred to as “heat soak.” The term heat soak isn’t really used correctly in the hot rod world. And specifically, when people talk about PD blowers. And even more specifically when talking about Centri vs PD comparisons. I’m not going to get into a debate about what “heat soak” really is or semantics though, so I’ll leave it there. We’ll just call what just about everyone calls heat soak by calling it heat soak.

PD Blowers

With a PD blower, mostly due to the location of the sensor, you’ll see higher “cruising” IATs. A PD blower has its IAT sensor located in the intake manifold. The intake manifold is bolted to cylinder heads that run at about 200-220deg. In a lot of cases, the intake manifold will run at about 175deg (that is a temp I see on the outside of them, who knows what it is inside). Inside that 175deg “box” (the intake manifold) is your IAT sensor. When cruising around, there’s very little air moving through the manifold. It’s the same air being run through the blower, through the bypass valve, and back through the blower again in a loop. That means you get a lot of latent heat from the manifold, from the intake ports in the cylinder heads, and reversion heat from exhaust gases backing their way up out of the cylinders (look it up, too hard to explain here). You’re seeing an actual IAT temp while cruising around. You’re not under boost/load though so really it doesn’t matter what the IAT is, you won’t be hurting parts. When you whack it wide open, you introduce a LOT cooler air into the blower/manifold. When you go wide open you’re not adding your cruising IAT’s to your “boost” IAT’s. As soon as you whack it open you’re flushing the hot air that has been circulating through the manifold/blower out pretty much instantly. Frequently, you’ll actually see the IATs drop when you go wide open and then they start to climb again because of boost temps.

Because the IAT sensor is very accurate, very fast reacting, and effectively inside the motor, you’ll see higher IATs than a Centri blower. Especially when cruising around not under boost. Here’s a picture of the IAT sensor location in a PD setup (sensor not in hole).

IAT sensor location PD blower

Centri Blowers

As mentioned above, Centri blowers use the IAT sensor built into the MAF sensor. The Centri blowers re-locate the MAF from its stock location. Different companies put it in different spots. And some people, when dealing with aftermarket ICs, etc., put them in different spots than that. One thing they all have in common though is they’re not “in” the motor like a PD blowers IAT sensor. They’re in the piping somewhere between the intercooler discharge port and the throttle body. What this means is that the environment where the sensors are is nowhere near as warm as on a PD blower. Sometimes the sensors aren’t even in the engine compartment! You’re looking at a GIGANTIC difference in what you’ll see for cruising temps when one sensor is located in the intake manifold right above the intake ports and either floating somewhere in the engine compartment or even outside of it. The temperature differential between those sensor environments can be up to 150deg.

I’ve taken temps at the intake runner (the outside of it) on the stock composite intake manifolds and consistently see 165-175deg. At the same time, if you take a temp of blower piping where MAF/IAT sensors are located that’s in the engine compartment, you’ll see 100-120deg. If it’s outside the engine compartment, it may be as low as ambient. Taking all of that into account, how can you compare cruising IATs (what a lot of people quote) between a Centri and a PD blower? The answer is you can’t. The environments where the temps are taken are wildly different.

I only know of one person who put a bulb style IAT sensor in a intake manifold with a Centri setup. Their cruising IATs then read very near what you see out of PD blowers.

Here’s a picture of the sensor location on a Centri blower (in this case a Procharger).

IAT sensor location Centri blower

What the Kits Come with for Coolers

Centri

The ICs that come with Centri blowers right out of the box from the big vendors are pretty good size. They need to be. Because they’re blowing air through them, they need to be at least as thick as the piping is. And you’re talking about 3in minimum. Some of them are 3.5-4in. And, because they’re having the air that’s going through the motor run through them, they shouldn’t pose a restriction. A small IC core would do exactly that. So, the manufacturers package them with pretty big ICs because they have to. The sizes of the included ICs vary, but you’re looking at 800-1000cu in in volume for most. That number doesn’t mean anything to you at the moment. It will when you read what’s next.

PD

The heat exchangers that come with PD kits are criminally small. Because most systems run a 3/4in water line, they don’t need to be very thick to get the water in/out. And, because most people don’t understand the importance of IATs, they haven’t put consumer pressure on the manufacturers to supply bigger heat exchangers with their kits. So, are you ready for the number? Here it is………most of the kits out there come with heat exchangers that are about 175-250cu in. Yeah, THAT small. Yes, water does transfer heat faster than air so you would think that you could get away with a much smaller heat exchanger. But it doesn’t “math out” that simple. I’m not going to go into all the variables though—that would be its own article. I can assure you though that they aren’t nearly as large as they should/could be.

In a very basic term, you’re getting a lot more “cooler” with an out of the box Centri kit vs an out of the box PD blower. That right there is another reason why people think Centri blowers with A2A systems are better than PD blowers with A2W systems. It isn’t that the A2A/Centri combo is the technologically superior system. It’s that, as they come out of the box, the Centri/A2W combos are “bigger.” But, if you make the A2W system “bigger” too, things look a lot different.

How Fast the Cooling Medium Travels

The cooling medium in an A2A system is air. It’s what’s moving through the cooler(s). That air needs to travel at a speed/volume that’s the same as what the motor needs for air. A 500rwhp motor will need to move about 800cfm (cubic feet per minute). That’s how much air you’ll have going through an A2A IC.

The cooling medium for an A2W system is water. It’s what’s moving through the cooler(s). The water in most out of the box A2W systems is moving at 5gpm (gallons per minute). 5gpm equals .668cfm. Yes, read that closely that POINT six six eight cfm.

You can probably already see a problem here. The air in an A2A system is moving at 800cfm. The water in the A2W system is moving at .668cfm. Water transfers heat faster than air but not THAT much faster.

Clearly, out of the box, the A2A systems are again packaged better than the A2W systems. But again, this doesn’t mean that A2A system technology/behavior is superior to an A2W system. It simply means that the A2A systems are again, “bigger.” You can easily increase water flow with an A2W setup. You’re not stuck at 5gpm. We run our fast stuff at 27gpm. That 5gpm is nowhere near “maxed out.”

Note that the cooling medium speed differential between a A2A and A2W system is not as easily “mathed out” as saying “Holy smokes, even if you’re running the water speed at 27gpm (the highest we have run it) which is 3.6cfm it’s not even in the same galaxy as how fast the air moves in a A2A system!!!”. There are so many variables, curves, efficiencies, pluses, minuses, and “what have yous” when dealing with cooling systems that even if I understood all of it (I don’t), I would have to write a textbook to explain it all. I can tell you this though. On the A2W systems that we run at 10gpm we get really fast heat transfer and great cooling. The stuff we run at 20+gpm is out of this world. Will a A2A system always have a faster moving cooling medium? Almost certainly. Can you get water moving fast enough to get the job done and then some? Oh yeah, you sure can.

The Limits of A2A

There is an upper limit of an effective A2A system that’s quite a bit lower than a A2W system. And this all comes down to available space. There’s a point where you can’t stuff more IC in the front of the car. After you’ve maxed out the available room, you’re at the limit of how well the IC can cool. That point with a A2A IC is about 15-16psi (at least in a Mustang; something like a big rig with a huge frontal area would be different). Remember, it’s boost that makes heat, not horsepower. I’ve seen plenty of Centri or even turbo cars with A2A ICs that had to use e85, meth injection, or both to keep IATs safe over 15-16psi. And these cars had the biggest, nastiest aftermarket A2A ICs you can stuff in the car.

After 15-16psi, you’ll see most Centri cars using meth or e85 to keep IATs in check. The ones that don’t have high IATs and are down on power when things heat up and the ECU pulls timing.

If you go to the drag strip, you’ll see most, if not all, of the FAST Centri cars running A2W intercooler systems. This isn’t because they wanted to spend the extra money, deal with the extra complexity or have the added weight. They don’t have a choice if they want to keep IAT’s in check.

The Limits of A2W

The limits of an A2W system are quite high. This is because of two things. One, water transfers heat 26x faster than air. So, that’s a big advantage. And in drag/standing mile setups you can run an ice chest which is a dramatic improvement over an A2A system that, at best, is running air at ambient temps across the IC. Being able to run 32.5deg water that’s 26x more effective opposed to ambient air (80deg?) as a cooling medium makes a GIGANTIC difference.

I know of cars running 36lb of boost, which is a 525ish deg discharge temp, that run through the traps with an IAT of 50-55deg. That’s in a completely different universe than what you can do with a A2A system.

Who Is Using What – the Real World

Mercedes Benz and Cadillac are both running A2W systems on their newer turbo cars. A turbo and Centri blower are packaged almost the same. These manufacturers went way out of their way and at much more expense to run A2W systems opposed to A2A systems. And the OEMs don’t do that sort of thing unless they see a benefit.

Summary

-Most PD blowers in most cases have lower discharge temps per psi than Centri blowers do.

-Water transfers heat 24x faster than air.

-The sensors used to measure IATs between PD and Centri blowers don’t behave the same so they can’t be compared.

-The sensor location between PD and Centri blowers is completely different in regards to latent heat so “on boost” IAT’s can’t be compared closely.

-The sensor location between PD and Centri blowers is completely different in regards to latent heat so cruising IAT’s can’t be compared at all.

-“Out of the box” Centri ICs are a lot closer to their limit (size) than what you get with a PD kits heat exchangers.

-“Out of the box,” a Centri’s cooling medium “air” is at its limit of speed/volume. PD kits aren’t anywhere close to their limits and can be increased.

One could, in a lot of cases make the statement that “Out of the box Centri blowers run cooler than out of the box PD blowers do.” But that’s not what I see out of the masses. There’s an assumption that Centri blowers run cooler because the Centri/A2A combination is technologically superior. And you get statements like “Centri blowers run cooler than PD blowers,” and it’s left at that. And that statement is incorrect because it suggests that, all things being equal, the Centri/A2A combo is superior to the PD/A2W combo. In this case, someone will make that blanket statement, and then a hundred people will repeat it later. Blanket statements are generally not a good idea. In this case, it’s a really bad idea. To compound the problem the “data” people are basing that blanket statement on is either wrong or there’s no data at all. Comparing IATs between Centri and PD blowers is nearly impossible because of the differences in how they sample temperatures.

I’m not arguing that Centri blowers are better than PD units or vice versa. I’m not even arguing that A2A systems are better/worse than A2W systems. Like most things, there are pluses and minuses, and, in some situations, some stuff works better than others. Ultimately, a A2W system will be able to cool better than an A2A system. But, when you start to factor in available space, complexity, cost, weight, boost levels, etc., you’ll find that, in some cases, an A2A system is the better choice even though it has a “performance disadvantage.”

What I’m doing is bitching about the irresponsible statements that people make based on…………in most cases……………………….zero facts. This being one of those cases. Bad information like “Centri blowers run cooler than PD blowers” as a blanket statement spreads like a virus. A virus that’s main symptom is spreading ignorance. I wrote this as my own little shot in the arm to combat that spread.

If you have any questions, shoot us an email at departmentofboost@yahoo.com

Thanks!

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