[66bonne]

Does anyone know what a stock, belt-driven water pump flows in GPH ? I know it varies with speed but any info would be appreciated. I want to compare it to a Meziere 40 GPH electric pump.

Thanks, Jim

[engineer]

stock 18-23 gph. anymore and the radiator is overwhelmed. water passes thru too fast for the air to exchange the heat, thus the thermostat.

[66bonne]

engineer - thanks for the info, it answers a question for me. I put the 40gph electric pump on my street/strip car and noticed that the temp around town was fine but ran about 15 degees higher on the highway than it did with the belt-driven stock pump.
Sounds like the electric pump produces too much flow.
Thanks again, Jim

[JSchmitz]

Originally Posted by engineer

stock 18-23 gph. anymore and the radiator is overwhelmed. water passes thru too fast for the air to exchange the heat, thus the thermostat.

I think the water too fast theory is a myth. Stewart components (Cooling experts) agrees. Please read the following page: http://www.stewartcomponents.com/tec...ech_Tips_3.htm I would suggest reading all of their tech tips.

There is one problem with pushing water too fast. It's only on "old" style systems, where the radiator cap is on the inlet tank. In this case you can create too much pressure in the tank. This can push coolant past the radiator cap. New systems have the cap on the outlet tank. Aluminum radiators will also take higher pressure caps. Another advantage over the old stuff.

[Pontirag]

its not a myth. Stewarts website makes a few incorrect conclusions. They refer to velocity when they should be stating pressure. If you increase pressure in the system it will force water to those hot spots they mention. presure developed by the pump up to the rating of the cap. want higher pressure for a given pump get a higher pressure cap. If you get a higher volume pump and its capacity at a given rpm exceeds the ability of the rest of the system to flow you dont increase pressure you create a situation where the tips of the vanes in the pump begine to stall and airate the water. It initially occures at the tips of the vanes but as rpm increases above that point the stall occures further down on the vane causing greater airation of the cooling water. Airated water at any volume or pressure is less efficient at cooling engine hotspots.

a smaller diameter impeller is usefull at higher rpms so that the amount of flow remains the same thus the rest of the cooling system can do its job of transfering heat. The higher the rpm the smaller the impeller should be so that the cooling system continues to flow at the most efficient amount of gallons per minute its capable of transfering heat If you want to inclease the gallons per minute flow of any pump you should deal with the resistance down stream of the pump. That being the radiator.Three core as oposed to a two core. Four core as aposed to a three core. ect. This has two benificial effects it increases the volume of coolant that the pump flows (actually it reduces the resistance to flow) and it increases the area of the radiator so that the coolant cools off at the ideal rate.

the issue of an ac vs standard water pump pully is an issue that has come up more often. I dont know which is larger diameter but if you have a large diameter water pump impeller and you install a larger diameter pully the tip stall problem gets worse as the pump tries even harder to pump a given volume of water at a given rpm against the resistance of the rest of the system.Further more regardless how much resistance there is or is not. If you rotate a pump beyond a certain point tip stall becomes a problem no mater what.

cooling problems not related to other mechanical issues most likely are the result of operating a given pump at too high an rpm on a system that cant handle the additional volume

[JSchmitz]

Originally Posted by Pontirag

its not a myth.

Please elaborate.

[Region Warrior]

A/C cars use a larger crank pulley, and a smaller w/p pulley to increase impeller speed.

All w/p pumps were the same from GM(Pontiac).

[JSchmitz]

Originally Posted by Pontirag

its not a myth. Stewarts website makes a few incorrect conclusions. They refer to velocity when they should be stating pressure. If you increase pressure in the system it will force water to those hot spots they mention.

They are saying that you must flow a sufficient volume of water (or velocity) past those hot spots to prevent it from boiling at that point. So, they are not incorrect in their rference. Having the water at a higher pressure will force it towards that spot, and increase the boiling point. But, it won't cool the area as well as sending a higher volume of water past the point. If you installed a higher voulme pump and thermostat, you could increase flow and maintain the same pressure in the block. IMHO.

Originally Posted by Pontirag

presure developed by the pump up to the rating of the cap. want higher pressure for a given pump get a higher pressure cap

????????

Originally Posted by Pontirag

If you get a higher volume pump and its capacity at a given rpm exceeds the ability of the rest of the system to flow you dont increase pressure you create a situation where the tips of the vanes in the pump begine to stall and airate the water

On the first page of tech tips, they address water pump rpm. I don't know why the bulk of your arguement assumes that the water pump is going to turn excess rpm and stall the vanes. As I understand, (and I'm no expert) rpm is the key thing that causes any "prop" to stall. That's why aircraft props can only turn so fast. The tips cannot be allowed to go supersonic. At that point air becomes incompressable. I'm not as knowledgeable about vanes in a fluid.

Originally Posted by Pontirag

a smaller diameter impeller is usefull at higher rpms so that the amount of flow remains the same thus the rest of the cooling system can do its job of transfering heat. The higher the rpm the smaller the impeller should be so that the cooling system continues to flow at the most efficient amount of gallons per minute its capable of transfering heat

If the pump was designed as large as it could be, and still not stall at the max rpm, I think that would be ideal. We need to dertermine if we are talking race or street cars. I assume we are talking street. So, the cooling system has to operate in a wide rpm range.

Originally Posted by Pontirag

If you want to inclease the gallons per minute flow of any pump you should deal with the resistance down stream of the pump. That being the radiator.Three core as oposed to a two core. Four core as aposed to a three core. ect. This has two benificial effects it increases the volume of coolant that the pump flows (actually it reduces the resistance to flow) and it increases the area of the radiator so that the coolant cools off at the ideal rate

I don't believe that most clean radiators present a restriction to stock water pumps. The stock thermostat is the restristion. Even with a high flow thermostat, I doubt that you could overwelm a clean radiator.

Originally Posted by Pontirag

the issue of an ac vs standard water pump pully is an issue that has come up more often. I dont know which is larger diameter but if you have a large diameter water pump impeller and you install a larger diameter pully the tip stall problem gets worse as the pump tries even harder

I find it hard to believe that you are in this kind of arguement and state that, "I dont know which is larger diameter". The a/c water pump pulley is smaller. This spins the pump, and the fan, faster. Then you state, "if you have a large diameter water pump impeller and you install a larger diameter pully the tip stall problem gets worse as the pump tries even harder". This is the exact opposite. The pump would slow down.

[engineer]

sorry, as my engineer label is my career, you can pass a fluid thru an fixed area exchanger and not allow enough time for the fluid to exchange heat with the other fluid, in this case air.

[JSchmitz]

Originally Posted by engineer

sorry, as my engineer label is my career, you can pass a fluid thru an fixed area exchanger and not allow enough time for the fluid to exchange heat with the other fluid, in this case air.

Don't be "sorry". Present your argument with facts or opinions. Hopefully facts. It's hard to distinguish between the two on message boards. As engineer is your career, "How fast is too fast?". Is it the 18-23 gph you stated? What's ideal. If so, why would a company like Meziere sell a 40 gph pump. Especially when it is independent of crankshaft rpm. Then if you try to restrict the flow, according to Pontirag, you will cause the vanes to stall. I'm sure there is a limit. We are making a lot of assumptions in this argument (er. uh. discussion).

I'm certainly no expert on cooling system design. But, I will continue to rely on sources I consider expert on the topic. I take all of what I read, and try to form an opinion that makes sense to me. That's all any of us can do. There's a lot of opinion stated as fact. I'm sure Stewart components has far more hard facts, from real testing, than all of us put together. If you read their info., it addresses everything in a way that makes sense to me. Nowhere do they state that there is no limit to how much flow is beneficial. If someone has a credible source that backs up their argument, please post a link.

[MetalHead175]

Not to hijack the thread, but can you run a heater with an elec. water pump? I don't see a heater outlet hose hook up on it. Maybe I'm blind?
-Jason

[66bonne]

Originally Posted by MetalHead175

Not to hijack the thread, but can you run a heater with an elec. water pump? I don't see a heater outlet hose hook up on it. Maybe I'm blind?
-Jason

Yes, you can run a heater. The heater hose hook-up is on the timing cover, not the water pump.
Jim

[MetalHead175]

I feel really stupid. Went and looked like 20 mins ago...sorry for the stupid question!

[Geoff]

I agree with Jschmitz's comments. The tech tip recommendation on the SC website [ increasing pump speed to pump water faster ] is aimed at the average pump on the average engine. Manufacturing tolerances come into play. Obviously if pump dimensions are carefully controlled for optimum flow along with passage sizes & restriction sizes in the cooling system, then increasing pump speed might well be a backwards step. However when you see impeller clearances varying from 0.060" to 0.25" as reported for Pontiacs under this category, many pumps would be far from efficient & increasing pump speed helps overall flow.

66 Bonne,
Sounds like your elec pump is producing insufficient flow, not too much. Don't be fooled by the GPM numbers; they are free flow, not the actual flow once the restriction of the cooling system is added. When you are cruising, you are doing 2 to 5 times more rpm than at idle. That means if you are idling at 700 rpm, the engine may be turning, say, 2800 rpm cruising. That is 4 times faster than the idle rpm. At 2800 rpm cruise, your elec water pump now has 4 times as many heat producing power strokes to extract heat from compared to idle speed, but it is STILL only turning the same rpm [ & pumping the same water volume ] as it was at idle.

[surfnuke9]

When evaluating the cooling system on a car you also need to factor in the airflow across the radiator in conjunction with the fluid flow through the radiator.

Both are affected by the engine rpm assuming you are running a belt driven pump and fan. Obviously, airflow also depends on the vehicles speed. Factor in the varying outside ambient temperature and you get an even more complicated system to evaluate.

That would be why we all strive to seal the shrouds as best as we can (for those cars that have them) and why on some AC cars there were seals installed on the radiator support to block off any potential air bypass paths around the radiator core.

heat transfer in any heat exchanger takes time and a driving force (temp differential). Flow the coolant faster and you reduce the BTU/lbm of heat removed (assuming air flow rate and temperature is constant) It is a balance between the heat exchangers heat transfer capability, heat transfer surface area, flow rate of coolant and flowrate of air. Ignore nay one of these contributing factors and you can potnetially exceed your systems cooling capacity.

[JSchmitz]

Here is the response I got from Jack Wilson, at Stewart Components, cocerning higher flow:

"Higher coolant flow will always result in higher heat transfer. The idea of less/slower coolant flow to better remove heat from the coolant is dangerous. Pressure is equally important. Higher system pressure raises the vapor point of the coolant and it's ability to absorb heat. Most application cooling system components i.e.radiator,hoses etc. will tolerate only lower amounts of system pressure regulated by the pressure caps ability to sustain this pressure. Block pressure must be consistant from front to rear for uniform coolant distributaion thus eliminating hot spots and component damage. The higher flow water pump will increase this much needed block pressure and will equalize the coolant distribution through out the engine, thus eliminating a water pump that may be bias to the inlet side of the engine. The radiator becomes less efficient as the coolant outlet temps. approaches ambient temperature. Therefore, a low flow rate keeps the coolant in the radiator longer. The longer the coolant stays in the radiator, the lower the efficiency of the radiator."

[Pontirag]

If you use a factory pump in a factory system and dont rev the engine beyond factory rpm limits you should be ok. To take a bit of the load off the pump and to increase cooling go with a larger radiator.

If you are going to run your engine beyond the factory rpm limits then you should get a smaller diameter pump to avoid the tip stall .

vanes number dont factor in too much but more vanes will push more water per revolution but make sure your other system components dont become a restriction or you will get that tip stall effect again. If you have more vanes, a larger impeller and you operate the pump beyond its capacity to push water then each of those vane tips make the problem worse. That means that the tip stall could be producing airation in the cooling fluid that then flows across a hot spot where steam is being produced and creating an even bigger problem then either one separately.

Be careful to distinguish between experts. some are expert marketers and some are expert in technical fields. Stewart has not stated enough parameters in thier advertising to determine how they support thier claim. And it is only an advertising claim. remember that they are in the business to sell pumps. and in this industry, bigger is better even when it is not. They sold you and they sold me. I'm operating my pump at a reasonable RPM and its part of a cooling SYSTEM where all components are matched to each other and to my needs.

Larger pulleys turn the pump faster for a given rpm. It was a mistake to say I dont know. I do know but i did not want to loose the thread of the point i was trying to make other than to list it as another factor/misconception that people assume.

a pump that is as large as it can be may work ok bet then the factors of cost and HP drain come ito play. Its not ideal for the pump to be as big as it can be but only enough so to accomodate the demands of the system otherwise it is overkill. (bigger is better Syndrome)

most correctly matched pumps and systems pose no problem at all. Even a clogged radiator has sufficient factor of safety engineered into it. I dis agree that the thermostad is the choke point in a properly matched system, again consider the factory system with its factor of safety. A thermostad opens when a given temperature is reached if it closes then it slows down the flow of water to allow additional heat transfer to occure. high volume water pumps pushing water too fast through the system for heat transfere to occure serve no purpose and cause the thermostate to close. when those same high volume pumps are operating against a closed thermostat then at almost any speed you get tip stall and thus airation of the coolant which is more easily pushed away from the hotspot generating steam in that local thus causing the coolant to be unable to transfer heat . cooler water flows past the thermostad causing it to close further or completely and you end up having each component inn the system doing its job correctly and even efficiently yet at cross perposes.The system is not matched to its verious components or to the needs of the system as a whole

But if we were talking about that then we all agree the problem would not exist.

Flowing water past a hot spot has a minimal effect on cooling that hot spot if the water is boiling away from that hot spot and not able to transfer heat. If you increase the pressure, only enough to over come the pressure of the boiling water then you will have water rather than steam cooling that hot spot and transfering heat away. Think of how a fuel pump overcomes vapour lock in a fuel system. or how a pressure cooker is used to keep water from boiling at a given temperature/altitude.

Choose the highest pressure your system can operate safley at. Choose a smaller impeller if you intend to operate above 6800 rpm. and a larger impeller if you intend to operate below 6800 rpm. If you go with a pump with more vanes on the impeller and or operate at the higher end of the -6800 rpm range then go with a four core radiator.

if you still have cooling problems check ignition and assume nothing! Check fuel system and assume nothing and consider using the baffles the factory used on the ac cars. remember they functioned in Phoenix in the summer time with the ac on in traffic and offered a warrenty.

If you end up using an electric pump maybe consider a rheostat to vary the speed of the pump. Use a cap to vary the pressure.

I've noticed a trend where head builders are putting thermal coatings on the surface of the exhuaste runners to reflect the heat back into the exhuaste stream rather than have it transfered to and absorbed by the cooling system.

I curios about wilsons/stewarts statement that higher coolant flow will always result in higher heat transfer. That is not nessessarily true in all cases and not as it pertains to heat transfer in the engine. yes it does in a radiator but in the engine? Hmm?

The longer coolant stays in the radiator the lower the efficiency of the radiator? I completly disagree with that and furthermore it negates the need of a high volume pump.Better check with the marketing boys one that one! I agree a high volume pump is unnessessary. Which factor causes the water to stay in the radiator longer? The volume of the pump? the operation of the thermostat? the size of the radiator? How can some one make a generalised statement without stating the specific parameters that would suport such a condition and conclusion. Its contadictory and and kinda works against the whole bigger is better pump/ marketing thing. How long water stays in the radiator is a factor of thermostad operation. If the water spends too little time in the radiator then you overheat? Wilsons not giving enough information about the rest of the system to support his statement. Why does GM put a larger radiator in the system if it is less effecient then a smaller radiator? Hmm?

[JSchmitz]

I'm sure there is a upper and lower limit for flow. No one here has posted any numbers or facts that would indicate what is ideal. Marketing certainly could be a motive for Stewart. But, his reputation should has come from good results. I believe he has done research, and testing, to back up his theory. Have you?

I don't have much time to read through your post right now. I will later. But, I would like to know where you have come up with information about pump vanes creating aeration, and stalling. Is it your contention that factory pumps are all on the verge of stalling and aerating the coolant? Pontiacs don't turn very high rpms as a general rule. I would think the other makes, that turn high rpm's, would be having major problems with pump stall. I guess we should all be underdriving our water pumps.

[JSchmitz]

After reading your last post, I have decided it's pointless to debate this, or anything else, with you.

Go slow your water pump way down, add a giant radiator, and "Use a cap to vary the pressure.". Keep a close eye on those vane tips and boiling hot spots.

[Pontirag]

I'm not trying to sell you on any thing. I got a high volume water pump. it works fine. As you might say it is "IDEAL" for my aplication. I'm not impunining anybody's reputation. I'm just compelling you to think. If you already have the waterpump thats a start. put a low temp thermostadt in it agood radiator and watch that heater core. See ya at the finish line....dont be late