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dual radiators in the bed...question??

oneofthefewbmx

oneofthefewbmx

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ok guys, my friend just put dual radiators in the bed of his truck....my question to you is would it cool better if:

1. the water flowed through one radiator and into the other....like this

motor----[radiator]-----[radiator]----motor


2. or the water split before the radiators, and flowed through both at the same time, and connected back to go back to the motor....like this

motor----Y---[radiator][radiator]---Y----motor



ALSO....does anyone know what PSI and GPM a stock water pump pumps at??? thanks alot....
 
I'm going to venture that going through one radiator then the other would cool better than the other way. The reason is because the water flow through the radiator is what cools the water and if you split the flow before the radiator so that it goes through both at once it still only remains in both radiators for (XX) amount of time whereas going through one radiator then exiting and going through the second radiator you've doubled the amount of cooling time.
 
I have no idea on that. You must remember one thing though, if the water moves to quickly it can't cool. You must have a thermostat in the system and the coolant must not flow too quickly.
 
I disagree. :) The longer coolant sits in the engine, the hotter it gets, the less effective it is, and the more heat needs bled off the radiator.

Move the coolant faster, it doesn't stay in the block long enough to overheat, nor does it need to shed as much heat through the radiator. Thermostat is what keeps the coolant in the engine to maintain a set temp, not to "slow coolant down" for cooling purposes. If you don't pull enough air through the radiator though, it won't matter what you believe is correct.

It's a closed loop. The ONLY place heat can escape is the radiator. Increasing temp in the engine only increases temp in the system, which starts the overheating cycle. Engines heat up pulling heavy loads and uphill, if keeping the thermostat closed helped bleed off heat, they'd be designed to pop open and shut without smooth action, and you'd see that when driving. It doesn't work, or the manufacturers would do it.

Pull the thermostat in a non-cooling overstressed motor, and it will NEVER heat up. BTDT.

Trying to move too much fluid can cause cavitation of the pump or unwanted turbulence in the engine block, but when talking somewhat normal circumstances, that isn't an issue.

Two radiators is going to make the pump work harder, I would want a high quality performance pump in there myself.

At one point I thought these guys http://www.stewartcomponents.com/Stewart_faq.htm had some GPM comparisons, but I don't see them in a quick glance.

Bit more info: http://www.stewartcomponents.com/cgi-bin/yabb/YaBB.cgi?board=tech;action=display;num=1113748943
 
Actually Dorian you are wrong on this one. The thermostat has two functions, it is a valve that limits flow and also allows for a pre-determined temperature. If you remove a thermostat the water cannot sit in the radiator long enough to dissapate any heat so the engine will start to overheat. It is a viscious cycle that happens many many times as most of us know. I'm sure you're smart enough to understand the theory behind this cycle. There are variables to this topic as there are most other topics but depending where you live if you remove your thermostat usually the engine will run cool enough around town if you have a good enough fan and shroud but once you hit freeway speeds the overheating will start to take place because no matter how much air you have moving across the radiator it cannot cool water that doesn't stand in the radiator long.
 
Ran my car for months without one, thought the gauge was the problem. Car never got over what the gauge said was 100*, no matter how hard I pushed the car, freeway, city, you name it. Economy sucked, coolant was lukewarm at best.

Find me something that shows coolant sitting in the radiator works better that's believable :)

Coolant boils in contact with the hot metal, increasing the time it sits against the metal is counterproductive. It doesn't do any work if it gets hot enough to boil, and the engine overheats. You can't transfer heat when the coolant is boiling against the cylinder walls. This can be found anywhere, short quote off of http://www.evanscooling.com/articles/00Sep_DP.htm

"[FONT=Arial, Helvetica, sans-serif]The hotter the metal, the more vapor produced, the larger the vapor barrier becomes and the higher the metal temperature rises. These 'hot spots' become so hot that they become secondary ignition points and are the causes of engine performance limitations (ignition instability) and emission problems."[/FONT]

http://www.radiator.com/radiators/articles/radiator-myths.html
 
dyeager535 said:
I disagree. :) The longer coolant sits in the engine, the hotter it gets, the less effective it is, and the more heat needs bled off the radiator.
Click to expand...

Um not nessecarily true. there is a too fast and too slow the water needs time to absorb heat from the motor but it cant go so slow as to just sit and overheat.

Also, how does a thermostat work? It slow coolant down/ acts like a vlave to control flow/ movement (speed if you will) of water exiting the block. This in turn controls how much water is passed through the radiatior, and in turn controls the amount of cooling.

I guess overall your talking about whats going to coll and engine the best...never allowing an enginge to heat up (dont run a thermostat) is a good way but not the right way...There is a range for operating temps, the thermostat keeps it right where it needs to be, by controling the amount of cooling...
 
dyeager535 said:
Ran my car for months without one, thought the gauge was the problem. Car never got over what the gauge said was 100*, no matter how hard I pushed the car, freeway, city, you name it. Economy sucked, coolant was lukewarm at best.

Find me something that shows coolant sitting in the radiator works better that's believable :)

Coolant boils in contact with the hot metal, increasing the time it sits against the metal is counterproductive. It doesn't do any work if it gets hot enough to boil, and the engine overheats. You can't transfer heat when the coolant is boiling against the cylinder walls. This can be found anywhere, short quote off of http://www.evanscooling.com/articles/00Sep_DP.htm

"[FONT=Arial, Helvetica, sans-serif]The hotter the metal, the more vapor produced, the larger the vapor barrier becomes and the higher the metal temperature rises. These 'hot spots' become so hot that they become secondary ignition points and are the causes of engine performance limitations (ignition instability) and emission problems."[/FONT]

http://www.radiator.com/radiators/articles/radiator-myths.html
Click to expand...

Your talking to an extreme though. the water needs to sit against the metal for a least a short amount of time to be able to avsorb the heat...
 
thanks for all the info guys, but....does anyone know what GPM or PSI a stock water pump pumps....i need to know this to put it into my friction loss formula to see if the stock pump can pump this water through like 40 ft. of plumbing....thanks :)
 
79k20350 said:
Your talking to an extreme though. the water needs to sit against the metal for a least a short amount of time to be able to avsorb the heat...
Click to expand...

Well, we are talking on the order of what, 5000* during combustion, some of which is being passed to the metal that is in direct contact with the coolant. There is going to be some extreme temperatures right there!
 
4X4HIGH said:
Actually Dorian you are wrong on this one. The thermostat has two functions, it is a valve that limits flow and also allows for a pre-determined temperature. If you remove a thermostat the water cannot sit in the radiator long enough to dissapate any heat so the engine will start to overheat.
Click to expand...
Um, Actually w/o some sort of restrictor (T-stat, purpose built restrictor, etc.) on the discharge side of the cooling system the block pressure (higher than the rad cap pressure) needed to keep localized boiling under control doesn't develop. That is the real purpose of the t-stat once the engine is up to temp. W/o that added pressure you're going to have steam pockets, which don't cool worth a dang. THAT is what starts the thermal run-a-way process.

One of the reasons pure water is the BEST possible coolant is b/c it gains and sheds heat energy very rapidly. Using pure water has downsides in various locations (freezing, etc.) but for the absolute best cooling fluid you want pure H2O. Coolant mass flow rate (increasing/decreasing the speed of the coolant) has only a little bearing on the heat rejection rate.

Of more importance is the airflow rate thru the radiator and the size of the radiator (surface area) since those are the more limiting factors. Air does NOT pick up heat as fast as water does, therefore you need more air volume to have a significant impact on cooling. Think about when you insulate your home what are you really trying to do? You're trying to create a stagnant air pocket in the walls. Almost everything anyone here will tell you to do with an overheating engine involves airflow management, not coolant flow. Fans, shrouds, ducting, etc. All of that is about moving MORE air, not more coolant. Just the reverse of what you're trying to do in insulating a home.
 
You may have a hard time finding that, although I suspect Stewart has some info SOMEWHERE.

The first table here http://www.stewartcomponents.com/tech_tips/Tech_Tips_7.htm at least has their "stage 1" vs. a competitor, so you can figure a stock pump is going to be at best slightly less efficient than the competitor in the graph.

You'll also end up with some variables in the stock pumps, as I know GM didn't use the same impeller setup for all their engines. Probably a rough estimate is as close as you are going to get.
 
What I want to know is what kind of monster powerplant are you running that warrants two radiators? That thing must be producing some very serious heat to overload one 4-core radiator. I'm just curious, are you re-engineering the wheel on this one?
 
I know I read somewhere (David Vizard?) that the "slow coolant (aka w/t-stat) cools better" theory has been disproven. There may be more to it that just flow (yes, steam pockets, etc.)

Count me down with Dye on this one, at least 'til I can read up more :D

As for the dual radiators, I have to ask why? I would also theorize that the radiators running in series (as opposed to parallel) would impose more restriction, more load on your water pump :thinking:
 
if one radiator in the bed gets the job done, why in the world would you want two? There plenty of guys with just one rad in the bed. I mean, a second one is just added weight and lost space in my mind. If you put a stock rad in the bed and it doesn't cut it, try a nice big aftermarket aluminum one, I doubt you'll find a need for a second one.
 
well, like i said its my buddies truck....hes been having probelms keeping it cool w/ his 2 core so he upgraded to a brand new 4 core....we went out to shiloh ridge for a weekend and that still didnt cut it....so he put the new 4 core and the old 2 core both in the bed....also it is just a 350...i dont know what its deal is...he has also tried dual electric fans as pullers, and that dint work so he put another one in the front as a pusher as well to no avail....just glad it aint my truck :)
 
sounds like there is a bigger issue that needs to be addressed. could be a blocked coolant passage or something of the sort...
 
79k20350 said:
sounds like there is a bigger issue that needs to be addressed. could be a blocked coolant passage or something of the sort...
Click to expand...
glad someone said it! id get everything else in tip top shape before id hassle myself with effin two radiators. make sure its not gunked up, maybe replace the water pump with at least a new one if not a hi/po one.

im runnin a small block 400 (which is supposed to be a very warm running engine for a small block) and i have zero problems with a new 4 core radiator and a new water pump from autozone.
 
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