Rage I looked at your numbers twice just to make sure.. If I'm reading this pdf file correctly, you're in good shape. The guages always are off some.

Your real temps look awesome to me. Perhaps I'm reading it backwards??

Not to mention you are quoting "out". All you ever really care about is what's going back "in".. That is unless you have 300+ coming out which clearly you don't by the file you shared.

If possible, make sure the water and oil flow in opposite directions in the oil cooler. Much more heat extraction that way.

Would you happen to have a pic of the larger heat exchangers? Are they Sendure?

they are sendurs you might find pics under clayola crazys new headers

Hey Crayolacrazy, thanks for the info. Wow 800hp 496!

What is the oil temperature and oil pressure "after 7 to 10 miles at 96 to 100 mph" when you decide to run negative boost to cool things down? Is that the heated oil temperature coming out of the engine or cooled oil temperature going back into the engine after the oil cooler? What is your sea water pressure at the 96 to 100 mph? What drives are you running or are you running seperate transum mounted sea water pick ups for everything or just the intercooler or...?

I also am running the 120F thermostat.

Sorry for all the questions but I am getting desperate.

Pictures welcome!

Thanks,

Bill

Keep in mind that my data stops at ~280F 'out' oil temp because I arbitrily reduce speed from WOT when I reach that number to cool down the oil and that the oil temp is still climbing at that point. The max oil temperature that my engine will stabilize at is an unknown.

I am relatively new to the high hp marine performance engine game and rely on opinions of seasoned high hp marine performance engine people. There are widely diverse opinions on max engine oil temperature limits. Opinions differ on whether oil in or oil out temperature is the most important. Oil out /crankcase temp proponents seem to be greater in number. Individual opinions on the maximum allowable oil out temperature range from 230F to 300F. The mean seems to be ~250F and rarely higher than 280F so that is my personal arbitrary limit.

There seems to be three significant issues related to oil temp limit: damage/oxidation/breakdown of the oil, damage to delicate engine components (seals, hoses, plastic parts) and damage/high wear do to loss of lubrication (low viscosity/oil pressure). Hot oil viscosity rating is tested at 212F. I have seen custom tests run at 300F and the viscosity of all engine oils, including the best synthetics, drop to low single digits and all the oils are within a unit of viscosity or so of each other. The high end synthetics will oxidize/breakdown at a much slower rate than the lesser quality dino oils, particularily at extreme temperatures. Since the viscosity grade of the synthetic is inherent and with dino oil achieved with modifiers the later is more susceptible to falling out of viscosity grade from extreme temperatures.

My goal is 250F max oil out temperature at extended WOT running.

Maybe I am better off than I think.

I recently performed a hot oil bath calibration test of my dash oil temp gage/sensor versus a quick tip thermocouple both immersed side by side in the heated oil. The gage proved to be essentially dead on accurate for test range of 140F-280F. As on my engine I had a dedicated ground to the battery for the sensor and ran the same 13.4v battery voltage as the boat produces at WOT

You know, that makes total sense to me. However when I discussed this with Hardin Marine tech people thay said that they tested both ways and found zero difference in the drop in oil temperature in temp minus out temp. Also another seasoned engine builder said the same thing. Mine is currently parrallel flow but I may try the reverse flow (a more difficult plumbing problem for my install) since I am running out of inexpensive things to try.

ttt