I got my 04 s2000 about a year ago and it was definitely not stock by any means. I suspect it had a turbo at some point. But my issue is the car really struggles to hit operating temp. If I'm driving the car it will just never get above 1 bar. I noticed the rad fans were constantly running so i unplugged both of them and the car still heat up but very slow. Last night i let it get to the full 8 bars then drove it around town for about 5 minutes and it dropped to 6 bars. It has a aluminum after market rad, should i just go back to oem rad and fans? I don't do any track days or anything. The aluminum rad definitely looks nice but if my car can't reach operating temp then what's the point. I'm still trying to chase down the reason the fans are always on. They go to the factory connections so i don't believe it's wired up to be on constantly. Sorry it's alot to unpack but I'm trying to get this car back to its former glory.

 

Do you think the previous owner removed the thermostat?

 

I had that same thought so i will be checking that soon. The radiator looks massive probably 2.5 inches thick

 

The thermostat is what controls the temp, the fans should not be running unless the engine is up to temp.

Rod

 

yes i agree. But even when i unplug the fans completely it won't hit operating temp unless I'm parked. Granted it's about 40 to 50 degrees outside but i feel like it should still hit operating temp

 

Thermostat.

 

you may get a check engine light for improper coolant temp if it happens for a bit of time. When my thermostat got stuck open I had a check engine light about the coolant temp. My Mishimoto aftermarket radiator spit out a chunk of welding material and it was stuck in the thermostat and the thermostat could not close fully.

 

8 bars in the AP2 temperature gauge is roughly 190°F or normal. Any temperature below that is abnormal if the thermostat is working -- or even there. Gasoline engines work best at that temperature. The "bars" are pretty wide as far as the actual temperature is concerned. Modifry EC2 module had a nice picture if the gauge and the temp range that someone will fine and post (my search was fruitless).

-- Chuck

 

For efficiency you want to run hot(210-224f cylinder head coolant temp), for power you want to run cool 170-190. Some extreme race cars run really hot ~240f. Race car S2000's with aluminum radiators run thermostats that open ~168f, but this is a racing environment where you're pushing the car to its limit lap after lap. If you're just putting around town a full on racing radiator is way too much cooling capacity. At least you won't have to worry about overheating sitting parked in rush hour stop and go traffic, your clutch will hate you, but the engine will be fine.
~

 

where i live there is no stop and go traffic. I'm considering just going back to a factory radiator unless someone has a big aluminum radiator that actually works normally