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My final radiator upgrade

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Joined: 27 May 2005
Total posts: 33
Location: eastern PA
Gender: Male
PostPosted: Wed Jul 22, 2009 7:00 pm    Post subject: My final radiator upgrade Reply with quote

Finally got around to REALLY upgrading the cooling system. A few months back I found a double row, dual pass Ron Davis radiator at a flea market for $25 (too good of a deal to pass up). Though I wasn't sure if I could use it, a few weeks of staring at it got me going on how to fit it into an already tight engine bay.

(2 of the fins were previously repaired, but they look solid)

Here's how it works. A dual-pass horizontal-flow radiator moves coolant across the top half of the radiator on the first pass, then directs the coolant across the lower portion of the radiator face for a second pass. One reason this works is because the velocity of the coolant roughly doubles when the coolant is forced to travel across half as many tubes per pass. This creates turbulence in the tubes, exposing more coolant to the radiator tube walls and improving heat transfer. It also provides a bit of a restriction to coolant flow, reducing the overall flow rate of the cooling system and allowing the coolant to spend more time in the radiator. I think one of my problems with the single core Griffin was that it flowed too fast with this engine - the coolant didn't have enough time to really cool as it passed through the radiator (but that's just speculation).

I enlarged the radiator opening a bit so I could move the radiator as far forward as possible.

Here it is all mocked up in its final position. I already had the lower brackets made (just a "J-hook" to cradle the bottom of the radiator), so I just needed to bend and fit the brackets to their final position.

The top hose/inlet is a simple 1.5" neck that the hose slides on to. The lower hose/outlet though is a 3/4" NPT bung . . . so I got a copper 3/4" NPT fitting, trimmed the overall length down and soldered a "street elbow" on to it. I also tapped the bung a bit deeper so that the copper fitting would thread all the way in (no threads showing). The outlet on my fitting is now 1.25" - the stock lower radiator hose is 1.375" - so there sohould be no real restriction that I need to worry about.

top view of it mounted with the plumbing all connected - I found a formed hose that I could cut/splice onto the stock lower radiator hose and used a universal flex hose for the top

Home Depot pipe hanger to hold the long lower radiator hose away from anything it might rub against

** started to fill the radiator with water to flush everything out of it and noticed water puring out of the bottom/front core tube . . . I don't know how I didn't see it split and spread 1/8" open. I tried to silver solder it but couldn't get it to stick, so I filled it with as much JB weld as I could push in and then squeezed the core closed. I pressure tested it to 20psi and it's held, so I'll consider this a permanent repair.

Previously I was using a 14" fan on my single core Griffin radiator. I could fit one 12" or 2 9" fans with the new setup (not enough room between the radiator and the front cross member for the 14"). I did some math on how much coverage the fans would give on the radiator:
1x14" fan = 153 sq.in.
1x12" fan = 113 sq.in.
2x9" fans = 127 sq.in
So 2x9" fans it is then - combined they pull 22 amps when they first start spinning, but settle down to 10 amps at full speed. Even though I'm stepping down in fan size I should be golden since the overall cooling capacity is increasing (won't find out till I have to pull the trailer again).
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