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Radiator in the rear, booster pump?


Phizinza
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not sure about in a GL... 

 

I know the rock bouncers build their coolant lines smaller, so it increases pressure.  They run 1" stainless line to capped into the tubing of the buggy and then back to the radiator.  

 

Demo derby cars we just put them in the back and ran marine wet exhaust hose back to the radiator and ran open thermostat.  Engine was wide open all the time, but with 2 electrics fans on the radiator it kept the engine ~175F

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The buggy runs rear rad is a pain to burp air out but works well i also added a 6L heat exchanger inline to add volume to coolant sestem it holds 12 L  i use a sprint rad as is very light. Is mounted higher than engine I had to put a radcap filler off the upper heater hose to fill engine and front half of sestem. Have been useing this setup for 10 years and 20 different engines ea ej dident mater as long as all the air was out. Even drag raceing in 35 degre heat can run all day and never overheat

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I'd guess there would be a little friction from the additional length, but I'm sure it's pretty negligible.  My Vanagon has a high compression EJ25 in the rear with stock pump & thermostat.  No cooling problems whatsoever.  The radiator in the front does indeed have a bleeder screw up at the top.

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  • 4 weeks later...

An extra pump is a non issue.Your pumping water through a tube,it has no choice but to flow through the tube.Most important is to have a bleeder at the radiator and at the highest place on the engine.Not totally necessary but easier to fully bleed the system.

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The length and diameter of the plumbing DOES matter, even in a horizontal, closed system.  You get flow drag from the plumbing, which increases with length, reduced diameter and/or increase in flow rate.  Think of it in the same was as electrical wiring: The longer the wiring run, the more resistance the circuit has. so the more motive force (voltage, pressure) is needed to maintain the same flow rate.

 

Whether it will be a concern for the OP's situation is less clear.

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True but the additional drag wont cause the water to not flow.It might slow down the flown but that will be cancelled out by the extra metal tube acting as a heat sink-assuming that the OP does use metal tube for as much of the system as possible.In a closed system in reality when ever water pump impeller turns it will force water through the rest of the system assuming there is no air to compress.Which makes bleeding the system much more important than worrying about the effect of extra drag on the system or adding a booster pump

Edited by Uberoo
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You have a valid point that the extra tubing will help dissipate heat.  I also think that, given proper sizing of tubing, flow drag will not be a major concern.

 

I do, however, think that ignoring the effects of flow drag is not a good idea.  Taken to boundary conditions (reductio ad absurdum, if you like), too much restriction will cause the flow to stall, and before that the pump will cavitate.  Again, I agree that it is not likely to happen in this case, just good to keep in mind that horizontal- and closed-systems are affected by plumbing design.

 

Cheers!

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The length and diameter of the plumbing DOES matter, even in a horizontal, closed system.  You get flow drag from the plumbing, which increases with length, reduced diameter and/or increase in flow rate.  Think of it in the same was as electrical wiring: The longer the wiring run, the more resistance the circuit has. so the more motive force (voltage, pressure) is needed to maintain the same flow rate.

 

Whether it will be a concern for the OP's situation is less clear.

assuming this analogy is true, why not increase the size of the piping for the long trip to the rear. then reduce it back down when it attaches to the radiator.

a larger wire / pipe will offer less resistance.

and for that matter there is no reason why you would need to use the subaru radiator. you could install one from a 1960 chevy pick up if it would fit or you could find one. i'll bet the pipes on it are larger.

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The analogy (IMHO) is accurate enough to mean that a larger pipe will provide less resistance.  Anything that reduces the flow rate (the current) will also decrease the drag.  And even better, the change is not linear but exponential.  Doubling the flow rate should cause a quadrupling of the flow drag; halving the flow rate by doubling the cross-sectional area (not diameter) should decrease flow drag to approximately one-fourth of original.

 

My personal desire is to replace the discrete radiator with distributed tube (or tube-on-panel) cooling.

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I added a 6 L expantion tank inline with uper rad hose gives me a 14 L coolant system and helps to keep it cool the more coolant the les chance of heat soak. I race in the middle of the day on hotest days of the year still takes 35 min to warm up in 35 degre heat

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