Swirl pot for superchager heat exchanger

[dhutton]

I used the same reservoir that the CTS-V used for my build. The reservoir is similar to the swirl pot concept. When the pump is running I can see the fluid churning in the reservoir and the reservoir cap is like a radiator cap in that it allows fluid to escape if the pressure gets too high.

Attachment 177969

Another engineer....



Don

[CarlC]

If adding a big reservoir to an intercooler seems to make sense and is a benefit, why don't we all add a five gallon reservoir of engine coolant and make the radiator smaller?

A large intercooler reservoir just becomes a thermal battery.

Assuming the transfer line lengths are similar and considered adiabatic (no radiant heat in/out of the lines), the only practical way a larger volume of intercooler coolant can make a positive change is if the reservoir is mounted in such a way that it sheds heat like a heat exchanger. That means in front of the radiator support and made of a thermally conductive material (aluminum). However, the amount of surface area vs. coolant volume makes this a pretty inefficient device, hence using a larger air/liquid heat exchanger is a much more effective option.

Note in the CTS-V reservoir that it has a column of coolant above the circulation pathway. This allows air to purge as well, and air is a nasty thing to have in an IC system and causes all kinds of pumping issues. Adding larger pumps to increase circulation volume can have consequences depending on the reservoir used. I'm going through that now and working on a fix.

[dhutton]

If adding a big reservoir to an intercooler seems to make sense and is a benefit, why don't we all add a five gallon reservoir of engine coolant and make the radiator smaller?

A large intercooler reservoir just becomes a thermal battery.

Assuming the transfer line lengths are similar and considered adiabatic (no radiant heat in/out of the lines), the only practical way a larger volume of intercooler coolant can make a positive change is if the reservoir is mounted in such a way that it sheds heat like a heat exchanger. That means in front of the radiator support and made of a thermally conductive material (aluminum). However, the amount of surface area vs. coolant volume makes this a pretty inefficient device, hence using a larger air/liquid heat exchanger is a much more effective option.

Note in the CTS-V reservoir that it has a column of coolant above the circulation pathway. This allows air to purge as well, and air is a nasty thing to have in an IC system and causes all kinds of pumping issues. Adding larger pumps to increase circulation volume can have consequences depending on the reservoir used. I'm going through that now and working on a fix.

Is the issue cavitation? Just wondering because I am working with someone who wants to use a big intercooler pump.

Don

[andrewb70]

Is the issue cavitation? Just wondering because I am working with someone who wants to use a big intercooler pump.

Don

Maybe the issue is that the water doesn't stay in the cooler long enough to dissipate the heat?

[dhutton]

Maybe the issue is that the water doesn't stay in the cooler long enough to dissipate the heat?

I’m not sure it works that way. It moves through the intercooler faster but makes more passes so the net heat dissipation should be the same as near as I can tell. Not 100% on this. I’ve been a little confused by the similar debate about high flow water pumps. Hopefully Carl will shed some light.

On the other hand the flow should not be so slow that the coolant reaches ambient temperature part way through the exchanger.

Don

[blitzer454]

Flow rate would make a difference, the coolant needs to stay in the radiator long enough to get cooled down, but that also means that the coolant will sit in the block longer getting hotter, so you have to find that sweet spot. I agree that larger reservoirs will only prolong the time it takes to get to operating temperature. If you're talking to a drag racer then all they care about is having the coldest air/gas charge they can get as it makes a bigger boom than a hot charge. But if you're like the most of us that want an engine to last another 50 years then getting up to normal operating temp quicker is better.

This argument reminds me of the thermostat argument that states that a lower temp thermostat will make the engine run cooler but in reality it will also just prolong the time it takes to get up to operating temperature.

[CarlC]

I’m not sure it works that way. It moves through the intercooler faster but makes more passes so the net heat dissipation should be the same as near as I can tell. Not 100% on this. I’ve been a little confused by the similar debate about high flow water pumps. Hopefully Carl will shed some light.

On the other hand the flow should not be so slow that the coolant reaches ambient temperature part way through the exchanger.

Don

We are going to stay civil, right ;-)

First, the challenge with the intercooler reservoir. This is the Magnuson part that has been in the Camaro since 2009 and has worked well until a few months ago:



Note that the return is a top tangential entry that creates the swirl effect. This setup works fine with the Bosch - Ford pump but needs some help when it comes to using a higher flowrate pump.

Note how high the return pipe is on the reservoir. As the high capacity pump spins up to speed (mine has as soft start so great for observation purposes) the liquid level in the tank drops a bit (normal.) This now causes the higher flowrate liquid to pickup and entrain the coolant with air. The quick and dirty fix is to fill the reservoir to the very top and allow it to purge what it doesn't need / thermal expansion. It's a marginal fix, so I'm looking at making a 2" neck extension that keeps the return submerged while still allowing an air gap at the cap.

There are always arguments about thermostats, flowrates, etc. regarding heat exchanging systems. But...... my 2 cents.

* Thermostats determine the low temperature setting for the cooling system. If the engine overheats with a 180*, it will do the same with a 160* thermostat if the flowrates and conditions of both are the same when fully deployed. If the car ran at 180* with a 180* thermostat, but at 170* with a similar 160* thermostat and conditions, then something in the cooling system is weak. It had just enough capacity to maintain 180*, but not enough to maintain 160* under the same conditions. Why? Thermal delta. The greater the thermal delta the more heat is transferred.

As for flowrates.....

Heat is made up of units of energy. No need to go into the details of the units or their names for now, but let's just think of them as units.

Heat up a 1" steel rod red hot to 2500*F. Put it into liquid that is 2000*F for five seconds. It's likely still red hot. Put it into the same 40*F liquid for five seconds and it's much cooler. Why? More heat units were transferred in the same amount of time since there is a greater thermal delta between the rod and the coolant. Though seemingly a simple concept, it bears restating: The greater the thermal delta, the greater amount of heat transfer within the same amount of time.

Turbulence in a cooling system is a good thing. Imagine hot coolant moving through a tube where the OD is exposed to air that is at lower temperature than the liquid. Naturally, heat from the coolant wants to move from the hot liquid, through the tube, and then into the air in order to try and reach thermal equilibrium. As the coolant enters the tube the layer nearest the wall will slow down the most while that near the center flows fastest since it is farthest away from the source of frictional drag. If the flow is perfectly laminar (as in laminate/layers) then the fluid in the center stays hotter than that near the tube wall. Knowing that having a high thermal delta is good for heat transfer, turbulent flow is good in order to circulate the fluid around inside the tube and move the higher temperature liquid in the center to the tube wall. The idea is to maintain the highest thermal delta possible in order to maximize heat transfer. More heat units moved to the air means more heat units moved out of the engine.



So why is extra flowrate typically good? Since higher temperature fluids are introduced into the heat exchanger (radiator) at a higher rate, a higher thermal delta exists between the fluid/tube/air. The higher the thermal delta, the more heat units are moved. This assumes that the pressure in the system is high enough so that boiling of the liquid does not occur.

Remember all the problems with steam pockets in the engine and the overheat conditions that follow? That is where restrictors come in. The restriction creates two conditions: 1) A higher liquid pressure in just the engine which leads to a higher boiling point, and 2) It also allows for a lower temperature liquid to enter the engine, hence decreasing the chances of localized boiling. However, the restrictor is slowing down the fluid, which reduces thermal delta in the radiator. Less heat units are transferred out to the air since cooler coolant is leaving the radiator vs a non-restricted system. With a big enough radiator the restrictor may work just fine under some conditions, but not all.

Can a higher flowrate pump cause localized stagnant/dead spots/steam when in a system that was designed for a lower flowrate? Maybe, maybe not, but a restrictor will not allow for the flowrate changes needed to help maintain constant coolant temperatures under varying environmental and loading conditions. That’s the job of the thermostat. However, there must be sufficient radiator thermal, pump flowrate, and fan flowrate capacity to allow the thermostat to its job. Cheaping out on a “maybe” radiator with a dinky fan with no shroud and a who-know Chinese water pump is a recipe for frustration.

[dhutton]

[dhutton]

We are going to stay civil, right ;-)

Don’t be afraid to tell me straight out if I am wrong. I’ve been spanked more times in design reviews than I can count. I’m here to learn....

Don

[CarlC]

Me too Don ;-)

[John McIntire]

I feel like I need to make a monetary contribution to Larry for the education I'm getting here at PT.com!

Continue on...

[CSG]

Don’t be afraid to tell me straight out if I am wrong. I’ve been spanked more times in design reviews than I can count. I’m here to learn....

Don

It took me YEARS not to want to straight out fight when they would poop on my design packages...

[dhutton]

It took me YEARS not to want to straight out fight when they would poop on my design packages...

I eventually became a chief engineer. The poopee became the pooper. I tried to be a little kinder and gentler but didn’t always succeed.... I always tried to touch base before the reviews to help avoid a gang spank review....

Don

[dhutton]

Would be cool to see an accurate Flotherm model of the intercooler system. Could vary coolant flow, reservoir capacity etc and see the real effects on air charge temperature.

My personal Flotherm license expired last week or I’d give it a go.

Don

[CarlC]

The modern OE IC pumps are pwm controlled. When they make their way to the aftermarket they get "dumbed-down" and just go for the full speed simple connection. I'm working on a circuit that will provide variable speed / PWM control.

It's always fun when the customer gives you the gang spank ;-) Such is the life of a three decade bearing sales engineer turned semi-pro gasser guy.

[John McIntire]

Carl,

What parameters do the OE's use to control the pwm of the intercooler pump? Boost PSI? Heat exchanger water temp? Little bit of everything?

[cwylie]

Bringing this back up because I thought it was a good discussion.

[srode]

Thanks for bringing it back up, I hadn't read it till now and it's a great discussion. Not sure the problem that's being solved after reading it other than perhaps removing entrained air from a system?

A little surprised the marginal gain from heat transfer out of the reservoir wasn't mentioned, but in the scheme of things it's not significant compared to the other levers to improve cooling.

[andrewb70]

Carl,

What parameters do the OE's use to control the pwm of the intercooler pump? Boost PSI? Heat exchanger water temp? Little bit of everything?

This was brought up at a good time. I just ordered a CWA150 pump for my GTO. It's PWM controlled. I have the ability to control it that way with my Holley Dominator. However, I would love to know what parameters the OEMs use to determine the speed of the pump. I have my obvious suspicions, but a firm confirmation would be good.

Andrew

[Bigblockscott]

This was brought up at a good time. I just ordered a CWA150 pump for my GTO. It's pwm controlled. I have the ability to control it that way with my Holley Dominator. However, I would love to know what parameters the OEMs use to determine the speed of the pump. I have my obvious suspicions, but a firm confirmation would be good.

Andrew

Andrew what does the rest of your HX set up look like? I'm starting to build mine for my LSA swap and looking for ideas. Also curious as to what sensors I should look to integrate into the system.
Does that CWA150 pump come with the wiring harness pig tail and do you need a stand alone module for the PWM or can the Dominator handle all of it?