I have an unusual problem – my oil temperature is about 40F lower than my water temperature. I have 2 oil coolers and 1 water radiator.

I’m considering converting 1 oil cooler into a water radiator.  Obviously my oil temperature is going to increase, but if the water temperature is improved significantly will this also help in reducing the rise in oil temperature.  So far, my experiments have shown that reducing the oil temperature has little effect on water temperature.

Does anyone know if reducing their water temperature also reduces oil temperature? – or are the two systems mostly independent?  

Jeff Whaley

The ideals would be 160-180 water and 160 max oil temps.

 

Water temps track power output slowly. Water (coolant) is taking heat out of aluminum and can do this at a very high rate (aluminum radiator). So water temps wander up and down slowly with power changes.

 

The oil is a poor conductor of heat. Hard to heat and hard to cool. The cast iron rotors are cooled by oil, badly foamed sprayed into the center holes from the jets in the crank. So rotor temps are difficult to control. And rotor temps can limit HP if not well controlled.

 

High rotor face temps limit cylinder filling and "in effect" reduce the engines displacement. Part of rotor cooling is the intake charge absorbing a lot of heat (Radiant energy) from the rotor face. When this is going on, the high charge temperatures decrease the charge volume ingested, increase burn rates, and moves you closer to a detonation event.

 

Not usually a factor in NA engines or very low boost turbos. So long as no other factors are in play, like a spark plug with too high a heat range, a burr on a ground electrode, best power mixture, (stay lean or rich of best power), ignition advanced too far. Or oil too hot, or carbon build up on the rotors forming a glow plug.  

 

Once you have the oil too hot, it will take a while to get the temps back down. You must reduce fuel consumption. Hotter oil, more foam, worse conductivity, longer cool down time.

 

Also keep in mind that the over heated water or oil is making the coolers more efficient, so the effect is not quite as obvious. Too hot is actually way to hot.

 

In racing I told the driver to short shift when the oil was too hot. Like 180-190. So instead of shifting at 9,600, shift at 9,300 for a lap and see if it comes down a bit.  This never worked out, because the driver never blinks for 45 minutes and his drivers suit is wet from adrenaline running out of his nose. So I installed a second dash board with a movie camera pointed at it. Very informative. Missed shifts, wrong gear, not close to the rev limit, on the rev limiter, no regard for temps????????????? Like talking to the cat.

 

Too low an oil temp is one curse I never had. With 3 Setrabs.

 

The actual temps would be nice to see......

 

Lynn E. Hanover