This is long winded but a story of chasing an overheating problem that I went too far on right at the end. The engineer and help from C & R rad was incredible, thanks Mark. All the listed steps are the standard point by point checks but I then got frustrated and went bigger is best with a radiator choice. I was so close then created my own next set of problems masking all others, ones I already solved.
Being based in sunny Arizona and tasked with making cars reliable and enjoyable the bane of overheating has been a long nightmare. Although self proclaimed I do consider my abilities at least fair. I was just taught a new lesson from an engineer at C & R Aluminum Racing Radiator
http://www.crracing.com/ . We spent 1/2 an hour going over testing and theory. In the end I had TOO MUCH radiator and this caused the overheating. I was close before the rad. change masking the end result.
1. We went over the basics of engine performance (meaning was it running close to proper settings).
2. Was the coolant flow system at full performance potential. Did I have water pump overdriven or running faster than the crank by 15 to 20 %. The W.P. pulley should be 20 % smaller than the crank pulley and the pump should be in good condition.
3. Did I have a T-stat and at a realistic open point. If you want the engine to run at 180 why install a 160 T-stat. Do not remove T-stat as you remove the ability for stem to cycle and therefore must live with the average of all conditions.
4. Did I have system pressurized to proper level to increase heat transfer and decrease boiling point to operating levels. A system pressure of 12 to 14 works but if you run hotter it will puke coolant and game over, run a higher cap to have a little safety net I like 18 PSI. It is not high enough to damage other items but keeps coolant in the engine.
Now we can get to the radiator and is it enough surface area to cover the heat generated? More is better when talking frontal area but it must have air flow to be usefully.
5. Frontal surface area and ducting of air intake is a key. 360 degree front ducting means no open bottom to dump air pressure at speed.
6. A shroud and GOOD pull fans on the back side to force airflow at lower speeds is needed. Fans are a biggie here and many are advertised as having a much higher flow than the real world when you restrict the inlet to them... like a radiator !!!! Next is proper amperage supply to these fans, if supplied with low voltage or low amperage then their performance drops like a rock. Use a relay to supply full system voltage and amperage in the 30 to 40 amp potential range. Do not tie into a 18 gauge wire found under the hood someplace that may be feeding your ignition ,fuel pump or whatever.
Now here is where I screwed the pooch!! Bigger has to be better and I did all the above but had a heating problem. It was now right on the verge of OK but would creep up and traffic was a killer. I could not get a larger frontal area so I went to a higher fin per inch and more tubes. I bought a C & R Cup radiator. If it worked in a Winston Cup car at 900 HP then this should be a piece of cake even at 120 degree Phoenix day... Right! Well I went to far and the high fin count and 4 rows of tubes made a 4 inch core. The electric fans could not move enough air through the restriction I installed. A 180 miles per hour would force air through but the twin 14 inch puller fans did not stand a chance. Even highway speed with the fans pulling away were marginal.
I went to a lower fin per inch count and 3 tube instead of 4 lowering the thickness and restriction so the fans could now move enough air to allow the radiator to work. This engine now runs on the T-stat regardless of what is happening. You can get to point of too much!!
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