I've had an Arduino embedded computer with an LCD screen that previously was just used for monitoring my ATF temps plus a few odds and ends. Just added an oil temperature sensor and a boost/vacuum sensor.
Attaching a sensor to the side or bottom of the pan can give inaccurate readings especially here because the pan has thick walls (reinforces block and bolts to transmission) and oil near the walls and bottom is largely stagnant. I'm also not yet brave enough to drill and tap into a pressurized oil gallery. Even if I wanted to tap there, I'd have to go through the ordeal that is dropping the pan just to have sufficient room, and I'd be worried I'd mess up and be out $400 for a new pan.
Instead I attached a thermistor to the outside of the oil passage between the pump and the oil thermostat as shown. This solves the problems with stagnant oil and thick walls because the oil is fast and turbulent after turning the 90 degree corner, plus the passage walls are thinner aluminum. I used Arctic Silver thermal adhesive, a thermally conductive epoxy normally meant for electronics, but the datasheet claims it handles temps in excess of 150C / 302F, so it seems up to the task.
Here's a quick shot after about 7 minutes idling while testing the cooling system for leaks after replacing the coolant thermostat. Ambient temp was 16C / 61 F. Interesting how fast the oil warms up at first (40C / 104F after just 3 minutes), but the temp rise slowed down after this, and was at 74C / 165F when I shut off the engine at around 10 minutes.
ATF takes a long time to heat up, since it's just getting pumped around without doing any work here.
Vacuum seems pretty healthy as well, starting at around 18 inHg and rising to 22 or so as things heat up and expand into the correct shape.
Next up is adding a datalogger so I can have fancy graphs to look at. Wish I had done this before winter so I could watch that freezing cold oil slowly come to life.
Attaching a sensor to the side or bottom of the pan can give inaccurate readings especially here because the pan has thick walls (reinforces block and bolts to transmission) and oil near the walls and bottom is largely stagnant. I'm also not yet brave enough to drill and tap into a pressurized oil gallery. Even if I wanted to tap there, I'd have to go through the ordeal that is dropping the pan just to have sufficient room, and I'd be worried I'd mess up and be out $400 for a new pan.
Instead I attached a thermistor to the outside of the oil passage between the pump and the oil thermostat as shown. This solves the problems with stagnant oil and thick walls because the oil is fast and turbulent after turning the 90 degree corner, plus the passage walls are thinner aluminum. I used Arctic Silver thermal adhesive, a thermally conductive epoxy normally meant for electronics, but the datasheet claims it handles temps in excess of 150C / 302F, so it seems up to the task.
Here's a quick shot after about 7 minutes idling while testing the cooling system for leaks after replacing the coolant thermostat. Ambient temp was 16C / 61 F. Interesting how fast the oil warms up at first (40C / 104F after just 3 minutes), but the temp rise slowed down after this, and was at 74C / 165F when I shut off the engine at around 10 minutes.
ATF takes a long time to heat up, since it's just getting pumped around without doing any work here.
Vacuum seems pretty healthy as well, starting at around 18 inHg and rising to 22 or so as things heat up and expand into the correct shape.
Next up is adding a datalogger so I can have fancy graphs to look at. Wish I had done this before winter so I could watch that freezing cold oil slowly come to life.