Swirl + Surge tanks, vs. just swirl

Jack,

Many people have gone to a more modern one tank setup, it does require some additional mods to optimize the cooling, beyond just eliminating the swirl tank.

IMO the best modifictaion is that completed and documenetd by John Taphorn of Space City Panteras, the article can be found here;
http://www.spacecitypanteras.com/styled-2/

Julian

The swirl tank (which DeTomaso called a system tank) is actually the least needed of the two. It is non-functional with a radiator cap on top anyway.

Keep the tall tank (expansion tank), mount it as high as possible, connect the lower connection to the suction of the water pump, add a fitting near the top of the tank to allow connection of the radiator vent. Run the expansion tank (which is now a header tank) with an air space above the coolant. I suggest the tubing between the radiator and "header tank" should be at least 1/4". Thus modified the radiator will auto-vent instead of trapping air, the car will run cooler and be easier to fill with coolant.

The purpose of a swirl tank (properly called a swirl pot) is to trap any air that is released as steam in the cylinder heads and vent it to a header tank, that's why its located on the outlet of the engine, its supposed to trap the air before it has a chance to circulate through the cooling system.

The radiator is where all the air in a Pantera gets trapped, so the radiator vent is the most important vent to "make functional". As it came from the factory it didn't function, because it was connected to the "system tank" which is higher in pressure than the radiator. Air will only flow to a zone of lower pressure than where you are trying to vent it from. A header tank is a necessity to vent air in any cooling system. The revision I detailed above converts the expansion tank into a header tank and makes the radiator vent functional.

-G

So the basic answer is no... I can not do a direct swap, ie just move the existing swirl pot, keep everything connected as is today and just delete the expansion tank?
This seems a little weird, as my expansion tank, takes overflow from the swirl pot via a pressure release cap. If the cap reaches a certain PSI, then it releases and dumps water into the expansion tank. Why can I not have the just dump to the ground?
My expansion tank does not feed back into the system... well, it doesn't seem too...
Thoughts?

quote:

Originally posted by jackcarter1971:
So the basic answer is no... I can not do a direct swap, ie just move the existing swirl pot, keep everything connected as is today and just delete the expansion tank?
This seems a little weird, as my expansion tank, takes overflow from the swirl pot via a pressure release cap. If the cap reaches a certain PSI, then it releases and dumps water into the expansion tank. Why can I not have the just dump to the ground?
My expansion tank does not feed back into the system... well, it doesn't seem too...
Thoughts?

I would say you could do what you are proposing, but finding another solution for a catch tank would be the best solution. There is plenty of room in that side of the wheelhouse.

If you routinely overflow the pressure tank, and it doesn't refill from the expansion tank, then your pressure tank cap may be faulty / wrong. Get a Stant #11230 cap. That is the proper cap.

An expansion tank is a recovery tank that operates under pressure. Some european manufacturers like to recover coolant this way (under pressure) instead of in an un-pressurized recovery tank. Otherwise the two tanks perform the same function. As the coolant heats up & expands the volume of the coolant eventually exceeds the volume of the cooling system and the excess is relieved by the radiator cap & flows into the "expansion tank" or "recovery tank". As the coolant cools off it contracts, the excess coolant that had been relieved into the "expansion tank" or "recovery tank" flows back into the cooling system via a small valve in the radiator cap.

Removal of the expansion tank and dumping coolant on the ground has two problems:

(1) When the coolant in the cooling system cools and contracts it won't have a recovery tank to refill itself from, so it will draw in air instead. That air will eventually collect in the radiator and create over-heating problems.

(2) Coolant is sweet, it tastes like cool-aid. Any coolant you spill on the ground is liable to be lapped up by animals and it will kill them.

As Dave pointed out, for your cooling system to draw coolant out of the expansion tank you need a radiator cap with the little inner check valve that allows coolant to return from the expansion tank, I'd be surprised if your car's radiator cap didn't have this valve. The pressure rating of the cap on the expansion tank should be a few psi higher than the pressure rating of the cap on the swirl pot (system tank).

-G

Aha... I believe I have an incorrect pressure cap. Hence the... "what is the point of this expansion tank"
That said, it sounds like the easiest thing to do is to keep the same system set up and move both tanks over to expansion tank area. That said, does anyone (supplier) make an brackets that are simple to install and hold both stock tanks.
Plus, to be sure, what is the specific expansion tank cap... vs. swirl tank cap. Stant cap numbers would be great.
Cheers JC71

George,

I like the idea you have, but can you please point out a car with this modification? How do you prevent the air bleed line from being a bubble trap at the top of the radiator?

quote:

can you please point out a car with this modification

My car has a VERY similar design as the one George has pointed out. It works very well and is self bleeding. The suction at the bottom of the tank draws the air out from the small bleed hose at the top of the radiator. I also have a small bleed line at the top of my heads that self bleeds any trapped air from the engine.

Ah, thank you!

George, are there other cars like this?

quote:

Originally posted by Corey Price:
George,

I like the idea you have, but can you please point out a car with this modification? How do you prevent the air bleed line from being a bubble trap at the top of the radiator?

4 members that I know of have converted to using a header tank: captaintobeys, JFFR, PLT-1 and JTPantera. John Taphorn (JTPantera) has extensively modified his cooling system including using a header tank. When mine is back on the road that will make #5. I'm working towards that goal and may have pictures of the modified tanks this week, if the welder doing my work is capable of working with thin gauge stainless steel.

Of course most new cars on the road have header tanks. And most race cars too. I am not proposing anything unusual here.

There already is a vent line to the radiator! It comes that way from the factory. And the radiator IS a bubble trap as it comes from the factory because the vent line doesn't function; giving the vent line a low pressure header tank to vent into makes the vent functional and allows the air in the radiator to flow into the header tank.

The design of the Pantera's cooling system mimics race car cooling systems. It includes small diameter pipes, a two-pass radiator, and two tanks having the appearance of a swirl pot and a header tank, the tanks commonly found in race cars. The design intentionally slows the coolant flow rate down in order to give it time to absorb heat in the motor, and time to extract heat in the radiator. That's why the pipes are sized as small as they are, that’s why the radiator is a two pass design, etc.

Air management in a motor’s cooling system is often taken for granted. Trapped air in the radiator or cylinder heads will inhibit the system’s ability to transfer heat and cool the engine. If the plumbing of the coolant system or the location of the system’s components tends to trap air the trapped air must be removed (i.e. vented). Air released in the cylinder heads as the result of coolant boiling must also be removed from the coolant because air in the coolant will reduce the heat transference properties of the cooling system.

The primary element needed to vent trapped air in a cooling system is a tank connected to the lowest pressure zone in the cooling system, i.e. the suction of the coolant pump. This tank is commonly referred to as a header tank; however it is also referred to by various authors as an expansion tank, a surge tank, or a de-gas tank. Without a low pressure header tank the vents in a cooling system will have nowhere to vent because coolant or air will only flow to a zone of lower pressure. The header tank will be equipped with small connections for vent hoses near the top, and a larger connection at the bottom that can be “teed” into the coolant pump suction line. The header tank is operated with an air space above the coolant to allow for the thermal expansion and contraction of the coolant as it warms or cools, and to allow for surge as the engine speed rises and falls. The header tank is also topped with a radiator cap, making the tank both the fill point and the pressure relief point for the cooling system. The tank is mounted as high as possible within the engine compartment to maximize its efficiency as an air collection tank, a surge and expansion tank, and a coolant system fill point.

Any air that collects within a cooling system after filling and “burping” is normally the result of coolant boiling in the cylinder heads. It is standard race car practice to use a swirl pot (aka a swirl tank) in the cooling system at the coolant outlet of the motor. If correctly designed, the swirl pot will spin the coolant around inside it, making any bubbles or air pockets collect in the middle, rise to the top, and exit via a small bleed tube in the top which is connected to the header tank. Thus the swirl pot keeps the cooling system free of air.

The inlet and outlet nipples on the Pantera’s smaller cooling system tank are configured in such a way there is no mistake it was intended to be a swirl pot. Since a swirl pot is not functional without a header tank to vent to, it is easy to assume the taller cooling system tank was intended to be a header tank. The radiator cap, the large bottom connection and the volume of the taller tank reinforce the assumption it was conceived to be a header tank. These are the two standard tanks utilized in the cooling system of a race car. For an unknown reason the Pantera design team revised the use of the tanks. The header tank became a pressurized coolant recovery tank known as an “expansion tank”; the swirl pot became nothing more than a convenient location for the radiator cap which DeTomaso refers to as a “system tank”. With the header tank converted for use as a recovery tank the radiator no longer had a low pressure tank to vent into so the radiator vent was relocated to the swirl pot (aka the system tank), which was an inept decision since the system pressure in the swirl pot is higher than it is in the radiator.

This change in the cooling system design was ill-advised. The Pantera’s cooling system has a problem with air being trapped in the radiator and it needs a functional vent system. If you want to read more about the design of cooling systems like the Pantera's, refer to Carroll Smith's three books: Prepare to Win (page 122), Engineer to Win (page 170) and Tune to Win (page 97).

-G

quote:

When mine is back on the road that will make #5

We also have converted to using a header tank so that will make you #6 George.

H all does anyone have photos of this in place and if they used the new stainless tanks and double tank bracket what mods were done to stainless tubes to the first tank.

cheers Cj

I am changing mine around as well. I have a expansion tank higher then the the highest point on the plumbing. It has a pressure cap to a purge tank.

In addition I am trying a float which expels air but closes with water. I expect it to only bubble some each time I start the car. It goes through a check valve into the over flow; not the expansion tank.

I will probably try this sort of setup, up front.

One of my clients we laser cut for is a nationally known seller of custom radiators. I had a conversation with him last week on this set up. Who knows if it is a good set up until I try it but he had some very good info.

People around the country....on front engine cars...which is a simpler set up then ours, are doing custom setups where they eliminate the radiator cap. You are seeing a lot of custom cars with fill spots in the their tubing instead of in the radiator itself.

Many of these people are getting overheat issues. There is one solution which they are doing which is fixing ALL their problems. They are ADDING swirl tanks.

The problem is the air hangs in the coolant and cannot really separate as well in a small tube. A radiator tends to act like a swirl tank so that helps most cars other then a Pantera. If you are not using the radiator to vent, and if you still have problems they have been solving them with swirl tanks.

I did not set mine up that way but I can't help but think that the Pantera is a more complex system simply by the distance the radiator is from the engine and by the fact it is a little lower.

For me I am going to try it without a swill tank. If I have problems I will leave room to convert the coolant tube to a swirl tank at its present location.




This is the air vent with float. It is in a cap which is also an alternate fill location.:

thanks you look like you are making a great job of your car.

I have the standard after market tanks supplied by OB Byers the pressure tank overflowing into the the second tank. do you have any thoughts regarding a air bleed from the radiator to this like the old system?
cheers Chris

quote:

Originally posted by comp2:
I am changing mine around as well. I have a expansion tank higher then the the highest point on the plumbing. It has a pressure cap to a purge tank.

In addition I am trying a float which expels air but closes with water. I expect it to only bubble some each time I start the car. It goes through a check valve into the over flow; not the expansion tank.

I will probably try this sort of setup, up front.

One of my clients we laser cut for is a nationally known seller of custom radiators. I had a conversation with him last week on this set up. Who knows if it is a good set up until I try it but he had some very good info.

People around the country....on front engine cars...which is a simpler set up then ours, are doing custom setups where they eliminate the radiator cap. You are seeing a lot of custom cars with fill spots in the their tubing instead of in the radiator itself.

Many of these people are getting overheat issues. There is one solution which they are doing which is fixing ALL their problems. They are ADDING swirl tanks.

The problem is the air hangs in the coolant and cannot really separate as well in a small tube. A radiator tends to act like a swirl tank so that helps most cars other then a Pantera. If you are not using the radiator to vent, and if you still have problems they have been solving them with swirl tanks.

I did not set mine up that way but I can't help but think that the Pantera is a more complex system simply by the distance the radiator is from the engine and by the fact it is a little lower.

For me I am going to try it without a swill tank. If I have problems I will leave room to convert the coolant tube to a swirl tank at its present location.




This is the air vent with float. It is in a cap which is also an alternate fill location.:

Do you mean plumbing it back? I think there is an issue with the air going back and forth and not purging as well as it should. I was wondering myself if a check valve would solve that.

quote:

Originally posted by Cowboy from Hell:
The swirl tank (which DeTomaso called a system tank) is actually the least needed of the two. It is non-functional with a radiator cap on top anyway.

Keep the tall tank (expansion tank), mount it as high as possible, connect the lower connection to the suction of the water pump, add a fitting near the top of the tank to allow connection of the radiator vent. Run the expansion tank (which is now a header tank) with an air space above the coolant. I suggest the tubing between the radiator and "header tank" should be at least 1/4". Thus modified the radiator will auto-vent instead of trapping air, the car will run cooler and be easier to fill with coolant.

The purpose of a swirl tank (properly called a swirl pot) is to trap any air that is released as steam in the cylinder heads and vent it to a header tank, that's why its located on the outlet of the engine, its supposed to trap the air before it has a chance to circulate through the cooling system.

The radiator is where all the air in a Pantera gets trapped, so the radiator vent is the most important vent to "make functional". As it came from the factory it didn't function, because it was connected to the "system tank" which is higher in pressure than the radiator. Air will only flow to a zone of lower pressure than where you are trying to vent it from. A header tank is a necessity to vent air in any cooling system. The revision I detailed above converts the expansion tank into a header tank and makes the radiator vent functional.

-G

In this modification, what happens to the tank caps. As existing, one is a high pressure and the other is just a cap with no pressure.

Are you suggesting to make the existing overflow tank pressurized with a pressurized cap?

Comp2
Off the subject, but only a quick question.
What is that silvery foil looking stuff on your firewall/bulkhead. It is very cool looking and a must have for my toy.
Also, you have one of the best looking engine bays I have seen.
Thanks
Jay

Thanks Jay, I have a few more tings to add so it will get a bit more cluttered.

The firewall is covered with Thermo
tec heat barrier. Easy to cut and apply:

http://www.jegs.com/i/Thermo+Tec/893/13590/10002/-1


I have it on the gas tank and well above the headers too:

Did I miss this small point?

You DON'T want to dump water in FRONT of the rear tire. This could cause a fancy dismount (excursion into the scenery), not something anyone wants to do.

At the very least, run the overflow hose to the very back of the car. We all know this, right?