Under or Over

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Dragnut

Dragnut

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I am going to buy a bracket, Pulley, and Alt. kit for my 408 from CVF...For the water pump pulley they offer a under drive or high flow option for the water pump pulley. So my question is do i want to slow down the water flow and keep it in the radiator longer or increase the flow? I am running this combo in a 66 Dart and have read on this forum about some guys having overheating problems in the early A,s with this engine combo....Thoughts??
 
It's about coolant flow. I'd recommend a high flow water pump. An overdrive water pump pulley will also help. 65'
 
I found this in a lengthy but excellent article on the physics of an automotive cooling system, written by the engineers at Griffin Radiators. If you want to read the entire article, here's the link: Pirate4x4.Com - The largest off roading and 4x4 website in the world.

If you just want to get to the conclusion without all the math, here's the summary:


The quick answer is, you should maximize:
  1. The flow of the coolant - the higher the better. More flow will always equal more cooling. Do this with a high-flow water pump, large hoses and passageways, large radius bends, and keeping the passageways as free of restrictions and blockages as possible.
  2. The flow of air through the rad - quality, high CFM fans (like those from SPAL), properly shrouded, as well as appropriate bodywork/ducting to ensure air flows through the rad and not around it. Don't lean the rad way back, as air will flow over rather than through it.
  3. The surface area of the radiator - use the biggest you can possibly fit. More details on rad tech to come shortly but again, short story is - buy an aluminum one from Griffin!
  4. The percentage of water in the coolant - for cooling, as we have discussed, water is best - use as high as a percentage as you can get away with (without freezing, boiling, or corroding the system)
  5. Pressure. Use the highest rated rad cap you can without blowing a hose or cracking the rad or some other component. More pressure equals higher vapour point (boiling point) which not only means less chance of steam pockets or boil-over, but also that the coolant can continue carrying away heat at temps beyond which lower pressure systems would have maxed out.
  6. Turbulence. Turbulent (or rough) flow of coolant through the rad ensures that as much hot coolant as possible is exposed to the cooling surfaces of the tubes. If flow is too smooth (laminar), only a thin outer layer of coolant is cooled in the rad and an undisturbed, hot core of coolant goes uncooled. That's uncool! Griffin have some super-trick ways of ensuring turbulent flow in their high performance rads.
 
19Greg69 said:
Yes, I have CVF high flow now but they are still only 1:1 ratio. I was hoping to bump mine up a bit from there.
Click to expand...
I went with there overdrive pulley when i bought the kit... it said “overdrive” but i didn’t double check the ratio...
 
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