aftermarket/high volume water pump for 4.0

98zjstroker

98zjstroker

Well-Known Member
Joined
Oct 14, 2009
Location
concord nc
So I had to bore out the cylinders in my 98 zj 4.0 to .040 over for the re-build im doing and wanted to upgrade my water pump to make sure it doesn't overheat. I might be a little paranoid and worrying when I dont need to but none the less I prefer to air on the side of caution. I haven't been able to find a aftermarket performance or high volume water pump for it. Does anyone know of any brands or places that might offer them or am I s{%t out of luck?
 
Quadratec sells them.

Really wondering why you want a faster flow? That equals less time to cool off inside the radiator...


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NickMaul said:
Really wondering why you want a faster flow? That equals less time to cool off inside the radiator...
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That's not how thermodynamics works, and is a really old myth that never made any sense. Wouldn't you want the least flow possible for the best possible cooling, by your argument? Also, why do people remove the thermostat for better flow, in an attempt to solve marginal overheating problems?

You want to get the heat out of the engine as fast as practically possible, and you want the deltaT between the radiator and the coolant to be as big as possible for best cooling efficiency. There's always a point where that curve flattens off though, and more flow really doesn't add anything of value.
Slow flow in the radiator (more time in the radiator) also means slow flow in the engine (more time in the engine), which leads to all sorts of problems lower heat transfer and uneven cooling within the engine.
That said, the entire cooling system needs to be able to take advantage of a higher flow pump, and I think most of these weird myths come from unexpected things happening. Stuff like too much pressure loss across a radiator or thermostat causing a high-flow pump to cavitate, which can make the high flow pump perform terribly.

If your cooling system sucks, a high flow pump may not solve any problems, and it may make things worse, but it's not because of coolant spending too little time inside the radiator.
 
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Besides the water pump itself add an additional trans fluid cooler to take some of the heat out of the rad/trans cooler. Did that on my XJ and noticed about a 10* difference in coolant temp. The flowkooler pimp is what I ran on my XJ as well with great results.
 
Fabrik8 said:
That's not how thermodynamics works, and is a really old myth that never made any sense. Wouldn't you want the least flow possible for the best possible cooling, by your argument?

You want to get the heat out of the engine as fast as practically possible, and you want the deltaT between the radiator and the coolant to be as big as possible for best cooling efficiency. There's always a point where that curve flattens off though, and more flow really doesn't add anything of value.
Slow flow in the radiator (more time in the radiator) also means slow flow in the engine (more time in the engine), which leads to all sorts of problems lower heat transfer and uneven cooling within the engine.
That said, the entire cooling system needs to be able to take advantage of a higher flow pump, and I think most of these weird myths come from unexpected things happening. Stuff like too much pressure loss across a radiator or thermostat causing a high-flow pump to cavitate, which can make the high flow pump perform terribly.

If your cooling system sucks, a high flow pump may not solve any problems, and it may make things worse, but it's not because of coolant spending too little time inside the radiator.
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So really a stock flow water pump is perfectly fine. Which is what I was hinting at :D


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I believe that it is a myth that boring a cylinder causes additional heat load to cooling system.

Stock water pump and stock replacement radiator with stock mechanical fan with clutch cools my stroker fine. It’s bored .040” over.

I don’t believe that the reduction in thickness causes a noticeable difference in load to the cooling system.

I had constant issues with running a taraus electric fan. Went back with mechanical, with good shroud and new clutch and suddenly no more cooling problems.

I remember years back, guys riveting a disc to the stock water pump impeller to improve flow at idle. Not sure if it made any actual difference.
 
Mac5005 said:
I believe that it is a myth that boring a cylinder causes additional heat load to cooling system.

I remember years back, guys riveting a disc to the stock water pump impeller to improve flow at idle. Not sure if it made any actual difference.
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The old 390 in my Fairlane was bored .040 over, I struggled with overheating. The new 445 stroker using a different .040 over 390 block. Seems to run much cooler even though it should be 100 or 120 more HP. So I don't quite believe in the thinner block makes more heat thing either.

Trying to fix the overheating on the old 390 I had a high flow pump. Long story short after a balancer came apart and the new balancer had 4 pulley bolts vs the stock 3 (Ford changed mid 67, the aftermarket ones use the new style) I had to come up with a new crank pulley. It started heating worse. I found a smaller wp pulley to get the ratio back closer to stock. That fixed the heating again, but the new ratio was 1.3:1 vs the stock 1.15 (the initial new balancer ratio was .9:1). Then it blew up a heater core, an upper hose, a heater hose then the plate behind the pump (Ford Fe pumps resemble a SBC) over a period of 6 months, usually after a wot pull.

The aftermarket high flow pump was literally a part store pump with a disc welded to the impeller. I replaced it with a stock part store pump and it's still cooling and not blowing everything up, though that could be the still higher than stock pulley ratio making it act like a high flow.

Stock style mechanical fans and good clutches move the most air in my experience, and don't forget if chasing a overheating motor about oil cooling. Oil coolers are the reason you see new trucks towing 30k with 400+HP. Remember water cools the head mostly, oil cools the pistons and rotating assembly!
 
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Mac5005 said:
I believe that it is a myth that boring a cylinder causes additional heat load to cooling system.
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Just higher power output, that's all that would cause additional heat. You would slightly change the distribution of heat along the length of the cylinder because of the thinner wall (slightly hotter locally in a few spots), but that should all come out in the wash because you're still producing the same amount of heat per power output as before.
I think this is another case of people changing a bunch of things at once during a bore/rebuild and then blaming a specific thing for a problem which has complex relationships..
 
I noticed a difference in my CJ 304, when I switched to the FlowKooler! And as for adding a plate to the back of the pump? That's what the FlowKooler Is. They sell the plate, if you want to go with your pump.
 
rodney eppes said:
And as for adding a plate to the back of the pump? That's what the FlowKooler Is. They sell the plate, if you want to go with your pump.
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in my willys, the 4.3 v6, I did this water pump mod. I just cut some galvanized sheet metal and used small rivets to attach to the impeller. Definite improvement in the cooling issue that I battled during it's life span.
 
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