A fair mount of my LSX friends run the steam vent directly to the top of the water pump with a tapped hole.
Coolant expansion tank question
- Thread starter KENS80V
- Start date
That would only serve to reintroduce any steam/air into the coolant flow and with the low position of radiators on the SLC likely to create another air lock situation. Take the steam vents to the top of the expansion tank. I would suggest that your friends are thinking of non- SLC type applications.
Howard Jones
Supporter
Jac I have a question for ya. I've looked for hours on Google and I can't find any reference to coolant pressure (s) in the various areas of the coolant system in a typical automotive system.
I assume it must be less in the recovery tank than the radiator cap value or it would open. Just what are we looking at. Do you think that pressure would be greater at the pump outlet, then lower as it leaves the engine and regains pressure as it travels back into the tubing and is transferred to the radiator? Does the pressure go up or down in the radiator? I would think that the radiator would have greater volume that the pipes running back and forth to it. Thus the pressure would be lower in it????????
Maybe the pressures are different throughout the system, That's my guess. Do you know of any real data on this question?
Others?
Eric. You HAVE to take ALL the air out of the system and deliver it to the only place that it should be. That is the head of air at the top of the expansion tank. This is the function of all the bleed lines. The other end of the bleed lines should be placed at the points that are most likely to trap air such as the back of the heads.
I run my expansion tank about 1/3 full of water and let the process force out any extra into the overflow tank.
After a full day at the track I usually find just a bit in the over flow tank and the cooled down expansion tank level about where it started out.
One last idea. drill a 1/8 " diameter hole in the flange area of the thermostat if you run one. Orientate the hole at the top. This will prevent any air from being trapped behind it when it is closed regardless if you are using the bypass hose or not.
All this little stuff is the reason cars that don't have cooling problems don't. It is just a matter of trial and error and some copying other successful designs.
ASK ASK ASK the people who's stuff works and COPY COPY COPY their designs!!!!!
I assume it must be less in the recovery tank than the radiator cap value or it would open. Just what are we looking at. Do you think that pressure would be greater at the pump outlet, then lower as it leaves the engine and regains pressure as it travels back into the tubing and is transferred to the radiator? Does the pressure go up or down in the radiator? I would think that the radiator would have greater volume that the pipes running back and forth to it. Thus the pressure would be lower in it????????
Maybe the pressures are different throughout the system, That's my guess. Do you know of any real data on this question?
Others?
Eric. You HAVE to take ALL the air out of the system and deliver it to the only place that it should be. That is the head of air at the top of the expansion tank. This is the function of all the bleed lines. The other end of the bleed lines should be placed at the points that are most likely to trap air such as the back of the heads.
I run my expansion tank about 1/3 full of water and let the process force out any extra into the overflow tank.
After a full day at the track I usually find just a bit in the over flow tank and the cooled down expansion tank level about where it started out.
One last idea. drill a 1/8 " diameter hole in the flange area of the thermostat if you run one. Orientate the hole at the top. This will prevent any air from being trapped behind it when it is closed regardless if you are using the bypass hose or not.
All this little stuff is the reason cars that don't have cooling problems don't. It is just a matter of trial and error and some copying other successful designs.
ASK ASK ASK the people who's stuff works and COPY COPY COPY their designs!!!!!
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Within relevent text.
Only thing that brass's me off from that is the owner who finally gets it right and then proceeds to tell you or me that he just had a great idea to fix his cooling system/whatever, but forgot who had been trying to help him for the last few times when he was crying in his coolant!
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Howard Jones
Supporter
Thanks Jac! oh and I agree, copying with attribution is flattery, standing on the shoulders of those who came before us and all that, stealing is just stealing. I'll look for the Smokey stuff, and I don't really know much about the new generation stuff like the LS series, and coyote motors, so I 'll leave it to the young'ins to figure it out.
As a matter of fact, all of these people who run this setup are non-SLC people... Would seem that just by law of exclusivity that most of my friends are non-SLC people :laugh: LOL
These guys are mostly turbo LSX folks, drag racer/weekend warrior types... street cars, but fast none the less.
Most of the literature on Smokey & others would be ~1970>>....
You might run into some issues yourself if you decide on a 400 SBC block in the future, those blocks have a few venting issues of their own due to the Siamese casting when used with 'some' aftermarket heads/gaskets that don't have steam holes drilled, gotta keep thinking all the time!!
Nothing wrong with that or having a wide info source, but you do need to be able to work out what works for your SLC application so you don't build yourself into a problem, the old measure three times and cut once adage pays dividends. What works for a drag racer wont necessarily last after a 1/2 hour of track racing/fast laps.
Howard Jones
Supporter
I have a 350 SBC in my SLC.................... What I have found so far on Smoky is pretty interesting, if I find the article in question I post a link.
Here's a tech article from circle track mag on cooling
http://www.circletrack.com/enginetech/1407_understanding_the_cooling_system_cool_under_pressure/
Here's a tech article from circle track mag on cooling
http://www.circletrack.com/enginetech/1407_understanding_the_cooling_system_cool_under_pressure/
A little info for the LS engine folks:
Starting at the water pump and following the numbers in sequence, here's the flow of the system:
One of the prime reasons for mounting a pressurized expansion 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:
When plumbing a surge tank:
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referrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><vath o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></vath><?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype>- The water pump pumps coolant out of the lower two ports on its back side and into the block.
- Coolant circulates through the engine block...
- ... and through the cylinder heads.
- Special LS-specific "steam tubes" or "engine vent lines" are installed on top of the cylinder heads. As vapour or steam will always seek the highest point, any steam pockets created by local hot spots, particularly in the cylinder head exhaust valve area, will migrate up and into the steam tubes which will carry them and a small amount of coolant away and either into a port located at the top of the rad and from there to the surge tank, or directly to the expansion tank (for the SL-C) where the steam is separated from the coolant.
- Coolant returning from the cylinder heads enters the two upper round ports on the left and right back sides of the pump
- Some coolant circulates through the water pump's bypass circuit and is again pumped back through the engine. This keeps the circuit flowing when the thermostat is closed.
- Hot coolant exits the smaller, rear "heater out" port of the thermostat housing on the water pump. This takes it to the heater core. The port is 5/8" ".
- After exiting the heater core, coolant returning from the heater passes through the expansion tank to keep coolant circulating through that tank.
- After passing through the heater core and then the expansion tank, coolant re-enters the engine via the larger, front 3/4" "heater in" port of the thermostat housing on the water pump.
- Hot coolant exiting from the engine that doesn't follow the pump's internal bypass circuit exits the water pump via the top 1-1/4" port and enters the top of the radiator.
- Hot coolant flows across and down through the radiator, cooling as it goes.
- Cooled coolant exits the radiator via the lower 1-1/2" outlet and returns to the inlet side of the water pump.
- Returning coolant is blocked from re-entering the water pump inlet if the thermostat is closed. When the coolant on the inside (engine side) of the thermostat reaches the temperature of the thermostat (e.g. 190° F) the thermostat opens and the cool coolant enters the water pump inlet to be circulated through the engine again, starting over at #1.
- A radiator bleed or vent port located at the top of the radiator connects to the expansion tank. Any air or steam in the system, especially that coming from the engine's steam tubes, will naturally seek the highest point and will therefore exit the radiator via this port and travel to the tank. At the expansion tank, coolant and steam enter and the steam or air is separated from the coolant. The lighter steam / air collects and remains in the tank at the highest point, just below the rad cap, to be eliminated first in the event the rad cap purges. The cooler, denser coolant goes to the bottom of the surge tank where it is collected by the flow returning from the heater core and circulated back through the system.
- In the event of a system over-pressure condition, the rad cap opens and burps excess coolant and steam out of the system to be collected by the overflow tank.
One of the prime reasons for mounting a pressurized expansion 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:
- 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.
- 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.
- 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.
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 expansion 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 tank.
- The 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 tank should be filled to a level just below the inlet ports. The continual de-aeration that an expansion 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!!
Howard Jones
Supporter
Here's a few more good articles I found. Most confirm much of what has been said, but conformation is good in and of itself.
http://www.saldanaracingproducts.com/Cooling System Principles.pdf
Like math, and SAE papers? Good stuff even if I don't have all the math covered
http://jestec.taylors.edu.my/Vol 6 Issue 1 February 11/Vol_6_1__094_108_Charitha ds.pdf
http://www.saldanaracingproducts.com/Cooling System Principles.pdf
Like math, and SAE papers? Good stuff even if I don't have all the math covered
http://jestec.taylors.edu.my/Vol 6 Issue 1 February 11/Vol_6_1__094_108_Charitha ds.pdf
Does anyone have the routing info for the coolant expansion tank that comes with the kit? The dorman one specifically.
Here 'ya go Eric:
Dorman coolant tank Dorman PN 20600200
to mount tank, go as high as you can with the spyder in place so you can access the tank cap and close the rear clip. Two brackets needed.
trim off any protrusions on the tank that get in the way.
connections:
the bottom of the main drivers side coolant tube requires a straight one-inch spud (long enough to get a hose on) that goes to the one-inch connection on the bottom of the Dorman tank. they use a straight piece of one-inch ID hose.
there are two 3/8" connections on the tank. the front one goes to the drivers side radiator bleed fitting. use a 90 degree fitting on the radiator.
the rear 3/8" fitting on the Dorman tank goes to the steam vent line on the engine.
Heater connections on the waterpump will go through the fuel tank access hole to the heater core (planned to be in the passenger side footbox for the Vintage Air system.
Dorman coolant tank Dorman PN 20600200
to mount tank, go as high as you can with the spyder in place so you can access the tank cap and close the rear clip. Two brackets needed.
trim off any protrusions on the tank that get in the way.
connections:
the bottom of the main drivers side coolant tube requires a straight one-inch spud (long enough to get a hose on) that goes to the one-inch connection on the bottom of the Dorman tank. they use a straight piece of one-inch ID hose.
there are two 3/8" connections on the tank. the front one goes to the drivers side radiator bleed fitting. use a 90 degree fitting on the radiator.
the rear 3/8" fitting on the Dorman tank goes to the steam vent line on the engine.
Heater connections on the waterpump will go through the fuel tank access hole to the heater core (planned to be in the passenger side footbox for the Vintage Air system.
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