Author Topic: Push or Pull  (Read 6159 times)

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Offline JimL

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Re: Push or Pull
« Reply #15 on: December 13, 2011, 10:16:32 PM »
In '99 we experienced a head failure (BGMR with turbo) that torched longintudinally through the combustion chambers, blew a hole through the timing cover, burnt the cam belt idler pulley bearing, and finally blew a water hose off at a firewall nipple.  Our rectangular tank held, though it did bow the sides and top.  That tank was made from 16 guage mild steel, with a single central baffle.  We used a pressure cap, with relief into a catch tank.  When the pressure spiked, the cap couldn't relieve fast enough but that's what happens with catastrophic failures.

The pressure cap question is a hard one to answer; if you raise the pressure it's harder for the water to boil.  I now run both radiator (w/ pressure cap and recovery tank) and large tank on my pushrod bike, but I run reverse flow (into the heads, and out through the block...I can make water heat but not oil/block heat).  I run the radiator immediately after the block (before the cooling tank) because a radiator works best when temperature differential is as high as possible.  This has worked perfectly (learned it from the guys at TRD).

A perfect example is Fuel Cell cars, which need a LOT of real estate for huge radiators.  Not because they make that much heat, but because the temp differential is too small (compared to ambient air temp), yet the stack needs temperature controlled accurately.

I forgot that lesson in 2010, running a pair of radiators in series (without a water tank).  I was very little better off than a single radiator, because the second radiator did not contribute much calorie absorption while adding additional restriction to the water flow!  Ooooops. :-P


food for thought, I guess.
JimL

Offline Stan Back

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Re: Push or Pull
« Reply #16 on: December 14, 2011, 11:41:46 AM »
I've been wondering about this pressurization talk.  For over ten years we've run about 15 gallons in our 18 gallon tank in the rear.  Highest temp (in the engine) past the 5-mile has been 185ยบ.  I've thought of restricting it to bring more heat in the engine which would be easy with the gate valve at the bottom of the tank, but have never done it.  The valve also helps when changing engines or such.  Hard to find 15 gallon containers if you gotta drain the whole thing.

Stan
Past (Only) Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club" -- 19 Years of Bonneville and/or El Mirage Street Roadster Records

Offline Kiwi Paul

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Re: Push or Pull
« Reply #17 on: December 14, 2011, 10:53:37 PM »
Stan....That is also quite a distance from front to rear to run hose and /or tubing.I`m sure there are losses in temperature over length. My car will also have a tank in the back, with an aluminum radiator inside, and I am going to use mainly aluminum tubing front to rear with a small amount of hose. I am planning to put valves in the system, in case of drain necessities. Not sure where to put these, front or rear. I wonder if there is any way to figure the heatloss in the layout, or maybe I can use your results and maybe downsize my system a touch.......any thoughts?...Anyone?

Offline Koncretekid

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Re: Push or Pull
« Reply #18 on: December 17, 2011, 07:04:13 AM »
Stupid question from an air cooled guy!

If I remember correctly, on a conventionally water cooled car, the reservoir is at the top of the radiator which is above the elevation of the cylinder heads.  After you fill the radiator and reservoir with water, you have to start the motor with the cap off and wait for the air bubbles to disappear, then refill the tank.  This is to ensure that air is not trapped in the uppermost crooks and crannies of the cooling system, especially not in the heads.

If you have a remote water tank in the trunk, which doesn't seem like it could be above the level of the cylinder heads, how do you bleed the air out of the system?  Putting a restrictor on the outlet might help, until you shut off the motor and the water shrinks a bit, pulling air back into the system.  I would have the same hesitation about running the water backwards, thru the heads first and out of the block at some lower point.

Any plumbers out there (Joe D?) could probably tell you a few stories about trying to get the air out of the hot water heating system on the third floor of a house.

Tom
We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!

Offline Peter Jack

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Re: Push or Pull
« Reply #19 on: December 17, 2011, 07:11:18 AM »
It's pretty common practice to put an air bleed at the highest point in the system although I have seen people jack cars into some pretty crazy positions to bleed a system. A bleeder at the highest point is definitely the easiest way. Sometimes more than one bleed point is handy if the water routing tends to be on the circuitous side.

Pete