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Guest Message by DevFuse
 

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Radiator in the rear, booster pump?


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19 replies to this topic

#1 Phizinza

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Posted 20 April 2013 - 04:37 AM

Has anyone run with a radiator in the back of the car using EA81 or EA82? Did it require an electric water pump to boost the flow?

#2 torxxx

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Posted 20 April 2013 - 02:35 PM

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



#3 Phizinza

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Posted 21 April 2013 - 05:04 AM

Thanks for that. Might give no extra pump a go and watch the temps

#4 torxxx

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Posted 21 April 2013 - 09:09 AM

as long as you run open thermostat, I dont see it being a major issue, the idea is no coolant sitting still more than anything



#5 Numbchux

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Posted 21 April 2013 - 08:37 PM

I've seen a few Porsche 914s with ER27s (mid engine, radiator in the front....) with just the stock water pump....

#6 WoodsWagon

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Posted 25 April 2013 - 11:25 PM

Plenty of VW buses and cars out there with subaru motors in the back and radiators in the front running just the stock pump and the stock thermostat. Just make sure you have a bleeder at the highest point in the system or it will be a PITA to get air bubbles out.



#7 ivans imports

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Posted 26 April 2013 - 09:48 AM

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



#8 ivans imports

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Posted 26 April 2013 - 09:49 AM

And i run stock thermostat no problems



#9 Gloyale

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Posted 27 April 2013 - 12:00 PM

Everything I've read and experienced is that if it's a closed system, the pump doesn't care how long the lines are.



#10 presslab

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Posted 27 April 2013 - 06:09 PM

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.



#11 Phizinza

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Posted 28 April 2013 - 11:45 PM

Thanks for the help.

 

We've mounted the radiator at almost the same height. I'll try it with the thermo and keep an eye on all the pipes and engine temps with my laser thermometer.

 

Cheers,

Phiz



#12 ivans imports

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Posted 30 April 2013 - 09:03 AM

Make shure air is all out or pump may cavitate is hardest to get air out of engine



#13 spazomatic

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Posted 30 April 2013 - 12:34 PM

I wouldnt worry about an extra pump. If you were pumping the coolant up an incline then maybe, but its just moving laterally so it shouldnt be an issue. I would definitely plumb in a capped high spot for burping purposes. Kinda like a fiero

#14 Uberoo

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Posted 24 May 2013 - 01:21 AM

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.



#15 NorthWet

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Posted 24 May 2013 - 08:28 AM

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.



#16 Uberoo

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Posted 27 May 2013 - 01:50 AM

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, 27 May 2013 - 01:59 AM.


#17 NorthWet

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Posted 27 May 2013 - 11:00 AM

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!



#18 johnceggleston

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Posted 27 May 2013 - 11:54 AM

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.



#19 NorthWet

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Posted 27 May 2013 - 01:33 PM

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.



#20 ivans imports

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Posted 28 May 2013 - 09:23 AM

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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