SLC Coolant Tank Group Buy?

Dave Lindemann

Lifetime Supporter
Mike - Thanks for the real world experience. I'm glad the tanking is working well.

Dave L

Dave, I've not noticed any issues with the tank, connections or engine cooling. The engine has run thru several radiator fan cycles - no overheating or purging of coolant from the tank/cap pressure overflow - using a 18psi to 22psi? cap IIRC.
 
As a side bar: The LS crate engine tech. sheet that came with the engine states the ECM will trigger the cooling fan at (100C) 212F. Even though I've read elsewhere that the fan will be triggered at a lower temp.? I noticed the other day that the fan kicked on and the KOSO digital coolant gauge read about 199F. I'm not worried about the disparity - just made a mental note. Has anybody else seen this. My temp. coolant sensor is reading/installed at that forward left side of the block bung -- near & in front of the exhaust ports.
The engines ecu and the Koso gauge may have different sensor locations. Before or after the radiator and where the coolant is entering and leaving the engine are possible examples. Those would definitely cause a gap in the two readings. Not sure if that is your cause or not since I am not familiar with your LS engine and consequently, the location you described.
 
Dave, I've not noticed any issues with the tank, connections or engine cooling. The engine has run thru several radiator fan cycles - no overheating or purging of coolant from the tank/cap pressure overflow - using a 18psi to 22psi? cap IIRC.

As a side bar: The LS crate engine tech. sheet that came with the engine states the ECM will trigger the cooling fan at (100C) 212F. Even though I've read elsewhere that the fan will be triggered at a lower temp.? I noticed the other day that the fan kicked on and the KOSO digital coolant gauge read about 199F. I'm not worried about the disparity - just made a mental note. Has anybody else seen this. My temp. coolant sensor is reading/installed at that forward left side of the block bung -- near & in front of the exhaust ports.
Using a gmpp crate engine ecu it will trigger at 203*. Your ECU temp sender is probably in driver front, gauge sender in rear passenger .... rear passenger head will be about 5-7* cooler.
 
Dave & Alex - thanks.

LS1 Tech & corvette forum both had threads that stated the ecm triggers the fan at about 203 to 204F. Seeing that the dash gauge is showing approx. 199F when this happens - I'm good. I still think it puzzling though that the sheet that came with the crate motor states 212F - which would be too high in my opinion.
 
Dave & Alex - thanks.

LS1 Tech & corvette forum both had threads that stated the ecm triggers the fan at about 203 to 204F. Seeing that the dash gauge is showing approx. 199F when this happens - I'm good. I still think it puzzling though that the sheet that came with the crate motor states 212F - which would be too high in my opinion.

I've seen it reported by GM as between 208 and 212. I think, although it's been a while since I drove it last, that in my Z06 it comes on around 205-208, so that may be for a production car ecu, not a crate engine ecu
 

Scott

Lifetime Supporter
I should get my SL-C in the next few weeks and I want one of these coolant tanks. Fortunately, all of the hard work has been done by others.

Is anyone else interested in doing a second group purchase? Based on the thread it sounds like we'd want at least 10.

I would also be interested in hearing feedback from people who have one from the first batch... I assume that most are installed by now and that some of the cars are running.
 

Ron McCall

Supporter
I should get my SL-C in the next few weeks and I want one of these coolant tanks. Fortunately, all of the hard work has been done by others.

Is anyone else interested in doing a second group purchase? Based on the thread it sounds like we'd want at least 10.

I would also be interested in hearing feedback from people who have one from the first batch... I assume that most are installed by now and that some of the cars are running.


I may be in for two depending on the time line.


Ron
 

Ken Roberts

Supporter
Try to have the steam vent lines welded in near the top of the tank in the air pocket and not in the bottom of the tank like the first batch.
 

Scott

Lifetime Supporter
It would seem to me that two bungs for the steam lines could be welded on the upper right side (see redline) and 90-degree fittings could be used to route the lines down the side. Not as streamlined as the first batch but perhaps more functional.
 

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If you have dual cooling fans, there is a separate trigger for each. The first fan typically comes on around 203-205, and the second fan comes on around 212.

If you're an old fart (like me) who grew up on small block Chevys and Fords, that seems a bit warm. But the LT/LS motors are designed to run warmer and more efficient. In fact, there seems to be agreement in the race world that you can run them at 235 without a problem. I'm not sure I want to test the limit...

I've seen it reported by GM as between 208 and 212. I think, although it's been a while since I drove it last, that in my Z06 it comes on around 205-208, so that may be for a production car ecu, not a crate engine ecu
 
This thread brings up a question I've had on my mind for a while.

Why not use an overflow tank instead of an expansion tank? Like an expansion tank, an overflow tank collects the excess coolant and then returns it to system when the engine cools.

Some of the advantages of an overflow tank are:
  • Since an overflow tank does not need to be built to withstand the cooling system pressure, it costs less.
  • An expansion tank must be mounted at the highest point in the cooling system. In a SLC, there isn't much real estate in the engine compartment above the motor. An overflow tank can be mounted anywhere.
 

Scott

Lifetime Supporter
At the bottom an excerpt from a really good article on cooling systems on why a surge tank, in addition to an overflow tank, is important:

Pirate4x4.Com - The largest off roading and 4x4 website in the world.

Note the importance of coolant level. For this reason I'm planning on adding 1/4" bungs on the front for an optional coolant level sight tube. Also note the importance of deaeration.

This tank from Radium has a nice sight tube and a separate deaeration chamber.

https://www.radiumauto.com/Coolant-Expansion-Tank-P261.aspx

I have found some 1/4", nickel-plated brass, 90-degree, push-to-lock connectors that are rated to 250 degrees. I am now looking for an appropriate tube. They apparently modeled air flow and cast an optimal shape so I'm not sure if an amateur version is worth doing or not. That said, custom fuel swirl tanks are made all of the time by merely making the inlet tangential to the top of the tank. This could be easily implemented by welding an aluminum tube inside the expansion tank.

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As can be seen, the surge tank is an important and very useful component of the system. Following are a few more details on the use of a surge tank:
One of the prime reasons for mounting a pressurized surge tank in the cooling system is the flexibility it gives in the mounting location of the rad cap. Because it is the pressure relief valve of the system, the rad cap:

1.Must always be located at the highest point of the cooling system - otherwise it will be impossible to get a complete fill of coolant and air will be trapped in the system. Also, when the rad cap is the highest point in the system, steam and air will naturally migrate to the area just below the cap. In the event the cap vents due to excessive pressure, the steam and air will be purged first.

2.Should be on the low pressure side of the system - otherwise the high pressure created by the water pump running at high RPM can tend to unseat the cap and blow coolant out, leading to overheating.

3.Should be located in an area of low coolant velocity so that the any steam or air can separate from the coolant, even at high RPM.
The surge tank provides the ideal environment for satisfying all three of these requirements, and provides a low velocity, low-pressure environment for de-aeration of the coolant.

When plumbing a surge tank:

• The bottom of the tank is connected to the inlet side of the water pump with a 1/2" or 3/4" line. In the systems shown above the heater return port is used for this purpose.

•A 1/4" to 3/8" vent or "bleed" line from the side of the surge tank is connected to the engine's steam ports (if it has them) or from the highest point of the low pressure side of the radiator. That is - if connected to the radiator, the bleed line to the surge tank must originate at the top of the radiator tank that doesn't have the normal radiator inlet from the water pump. This is because coolant velocity and pressure are high at that location which would force high velocity, high pressure coolant through the line to the surge tank, defeating the purpose of the surge tank's low pressure, low velocity environment for deaeration. The bleed line allows continual circulation of some coolant through the surge tank.

•The surge tank must be large enough to allow the air to separate as the coolant flows through it. Air in the system will then migrate to the area just below the radiator cap, again so that it will be forced out first if system pressure exceeds the radiator cap's rating.

•The surge tank should be filled to a level just below the inlet ports, as shown in the system diagram above.
The continual de-aeration that a surge tank provides can be a huge benefit to your overall cooling system. We already discussed all the bad things that happen when steam or air are trapped in the cooling system. In addition to those, consider that 2% air in the system results in 8% less heat transfer, but 4% air results in a whopping 38% less!! The continual de-aeration of the coolant may be enough advantage to allow you to run a smaller, easier-to-fit radiator with a surge tank than the size you would have to run with only an overflow tank, for instance.

If your engine doesn't have steam ports, and the rad is lower than the top of the engine, the bleed line to the surge tank must come from the highest point on the engine because this is where steam and air will naturally gravitate and get trapped. A fitting on the water pump in the same passage as the outlet to the radiator can be a reasonable compromise.
If you add a surge tank to a system that already has a rad cap on the radiator, you need to permanently seal the radiator rad cap location, or at least install on the rad a cap with a rating significantly higher than the surge tank cap will have, so that the radiator mounted cap will not open before the surge tank cap.
 
I purchased one when I was going LS3 and now going 1UZFETT so I do not need mine anymore. If someone wants to buy mine from me send me a pm.
Troy
 
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