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Re: Corax's '88 Runner
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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Trekker
Re: Corax's '88 Runner
I've been lugging around a NWMP fuel tank for the last 14 months and I finally got tired of moving it around to different locations, so I decided to finally install it today. It's supposed to be a gravity feed system with a hose running into a fitting where the main tank drain plug is on the bottom. Problem with this is I don't like the idea of having something hang even lower off the main tank, especially a brass fitting that could drain all my fuel if it gets hit hard enough.
So I thought of putting a shut valve on it (elec or manual) and have the aux tank drain into the filler neck vent tube for the main tank, but the filler neck is too high and I don't want to put a hole lower than that in the side of the main tank because I'm afraid it'll leak.
My final option is an electric fuel pump, but fuel pumps can get damaged when they run dry from heat build up and I would have no way of knowing when to shut off the extra pump. I can't find anything saying they are safe for short periods of dry running and likewise nothing about how they work except that they do not use a diaphragm.
This is what I came up with, though it may be a bit over engineered it should save the pump from running dry, and if the rest of the system wiring fails a jumper wire across the load side of the relay will still turn on the fuel pump (actually changed it a bit from the first idea, now I have the switches working on the ground side with the relay at the passenger side rear of the engine bay)
Red: fuel lines
Dk Blue: wiring
Parts: low pressure nitrous fuel safety switch (adjustable 2-5psi), fuel pump, momentary & toggle switches, relay, slight fuel line restriction (small crimp in steel fuel line to main tank)
- the toggle switch turns on the system, but the relay won't turn on the fuel pump until there is ~3psi at the low pressure switch
- press the momentary switch to bypass the pressure switch and turn on the relay and fuel pump
- pressure builds behind the restriction and makes the pressure switch close, the momentary switch can be let go now as the relay will stay on
- when the aux tank runs dry the pressure switch opens deactivating the relay and fuel pump
if I really want to get fancy, I was thinking I could run a wire from the + side of the fuel pump back up to the switch panel through an LED and on to ground as a "fuel pump on" indicator light
Installing the tank is easy, so I'll leave out the bits about drilling holes and bolting it up. It's the details that'll make it trouble free in the long run . . . like an exhaust heat shield so the gas doesn't get too hot (excessive vapor/boiling)
view from the wheel well - before I fill it for the first time I'd like to replace the rubber hose with steel braided to help deter thieves from thinking it would be easy to cut the rubber hose and steal my gas - I was also thinking a steel hard line would work, but I'd have to find another fitting first
transfer pump (universal, for a carb'd car) - I used 1/4 riv-nuts to attach it to the frame rail (still need to put a fuel filter inline to pretect the pump)
a bit of protection to keep the hoses from chaffing against the frame rail, it also keeps them tied together nicely so they don't move around much
a few months ago I had to repair the main tank fuel pump bracket because the metal line on the outside finally rusted through, while I was at it I added an extra line to dump the fuel from the aux tank into the main tank, I had actually extended that fitting down to the bottom of the tank in the hopes that it would work like a siphon once fuel starts flowing (in case the pump fails/doesn't work out I could still use the aux tank w/ pump removed)
I tossed my spare tire back under there and noticed that the tank didn't affect my departure angle at all, though if I drop off an obstacle the spare will definately take the hit. If I know I'm hitting any rough trails I'll just take the spare off and toss it in the back. I am planning on making some kind of spare carrier for the rear bumper - I always liked the idea of being able to carry 2 spare tires for longer trips.
rear view
Switches installed - turn the toggle on, press the momentary switch till there's enough pressure to trigger the pressure switch, let go of the momentary and the pump runs till the toggle is switched off or the pressure in the line drops (aux tank empty) - the blue LED is wired to the transfer pump V+ wire so it is on any time the pump is running
With the extra fuel on board I should be able to get a range just shy of 600 miles normal driving
(17 gal factory tank + 14 gal aux tank) x 19mpg = 589 miles
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new shoes
new shoes - 33x10.5x15 BFG KM2's on 8" wide black steelies with 4.5" backspacing + took off the dumpy looking JCWhitney universal rubber flares since the tires are inside the wheel wells again. I still don't have any lift on the front and don't plan on any, I do have a 1" body lift - I might have to tap the body seam at the rear of the front wheel wells a bit, but it doesn't have to get hammered flat. The rears fit fine after I bent the mudflap brackets a bit to angle them rearward.
initial driving impressions on road:
- I can break the rear loose exiting a tight corner once again in 1st or 2nd (2nd gear only does it if I'm in the power band).
- definately a bit "looser" mid-turn through the twisties than my well worn 32x11.5 BFG A/T's w/ 3.5" backspacing, but I kinda expected that. I'm hoping they'll stick just a tad better once the new tire smell is gone and they get scuffed in
- I'm pleasantly surprised with the level of road noise - I can only hear them if I'm off the throttle, and even then it's minimal
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