fan only kicks in when temps are getting high so car can still be running way off due to high temp even if fan hasnt kicked in
I have to disagree..
1. The fan switches on when the engine gets to the designated operating temperature.. which is NOT the maximum safe operating temperature.. but is set by the fan switch. Which was researched and developed by the factory when the engine was designed.
the ek9 rad is fine for road use but any kind of hard drive/track use its very poor, its actually thinner than ek4 rad which is something that i have never understood honda doing
2. Its a more efficient radiator because of the material the cores made from. Its designed for the stock setup and you can hammer the stock setup at redline in 5th for a WHOLE HOUR STRAIGHT! ..between 140-150 on the clock WITHOUT it overheating!! Believe me it did not overheat.. just used 3/4 of a tank of petrol for 120miles.
Have you ever seen one overheat on BMI reviews?, head-to-heads or testing?
NO, it doesnt happen on the factory setups unless theres a fault or somthing worn out. They always comment when cars struggle or overheat etc.
if you dont beleive me measure water temps at couple different points after hard drive and youll see true results with your own eyes
the rad you have now on your ek9 will be perfect (i assume its same length as oem but thicker core)
3. If its a standard engine and your using that oversized radiator youll be over-cooling it. The factory rad it perfect for a factory car
start by replacing your thermostat, if coolant is fairly new just reuse it, make sure to bleed system fully as slight air lock can cause temp needle to go stupid
4. This (the above) is bad advice, the most sensible and systematic approach would be to TEST the thermostat before replacing it. You could endup spending the money and still have a problem. Its best to identify the problem before you try and find a solution.
Heres how to test the factory thermostat...
I would reccomend you try limiting the airflow by covering up a couple of inches of the radiator as I previously mentioned, if it doesnt sort the problem, the remove and test the thermostat. If it does stop the problem then you know I was correct and you radiator is too efficient for your setup takign too much thermal energy out of the water. If it reduces the problem then cover a little more up and see if its any better.
A Sytematic approach is best.