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Mopar1973Man

Oil Temperature vs. Timing

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Posted (edited)

I found another secret I've got to share with the group. For guys with manuals or not using the transmission temp sender. Remove the test plug on the oil filter housing and then install the transmission temperature sender. 

 

The secret found.

 

If you want to find out if your over advancing timing its is super simple. Measure the engine oil temperature. When I started I was roughly +10°F over the coolant temperature. I was starting to test MPG in different RPM ranges. Found the lower bands tend to run hot oil wise and tend to be a bit low in MPG number still. After figuring out a new timing map now I'm roughly 20°F below coolant temperature on the flat highway run. If coolant is 197°F it can run 178°F to 181°F in oil temperature now. Since advancing the timing tends to burn more in the cylinder the block coolant was rising quite a bit and trapping more heat in the engine oil. Dropped 2° of timing in the 1,500 RPM range and this flipped the other direction to -20°F cooler. Worth it to install the sensor in the engine oil port.

 

Remember... When you seeing heat that is a percentage of work energy turned into heat. The more you can trim off the heat in every device right down to the rear axle this means more power being put to the ground efficiently.

Edited by Mopar1973Man
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Posted (edited)

I've been playing with this and its does work out to aid in setting up timing. If your timing is over advanced your engine oil will climb. Like excessive cruise timing it will slowly climb up then when you hit a hill and with goo retard the temp will fall again. This points out the cruise timing is too high. 

 

If one RPM range is too high that range will show a serious rise in oil temp. 

 

When your advance timing you forcing the burn to occur mostly in the cylinder and this transfer a percentage of heat to the coolant jacket. Excessive timing will actually force the engine oil temperature higher than the coolant. Keep in mind the oil cooler sees the cold coolant from the radiator. I've seen as low as 22°F difference between coolant and oil temperatures. 

 

More you retard the timing the more you building boost and making the burn occur on the downward stroke and push expanding gases into the turbine of the turbo. More you advance timing the more the burn happens in the cylinder transferring heat into the coolant jacket but also efficiency is better. Now its about gaining a balance to heat and timing.

 

Now between listening and watching oil temperature you can hit nearly a perfect timing or least within a few degrees.

 

SUGGESTED: Keep oil temperature about -10°F below coolant temperature. 

Edited by Mopar1973Man

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More to add to this and learning still. 

 

When you watching engine oil temperature for tuning make sure to run a good long distance to get a stable engine oil temperature. Like for me the run to Riggins, ID is a 1% grade down hill. This gives a fake low oil temperature reading. Make sure to do you measure after a good climb or long straight run. Like today I made a trip to McCall, ID and that is a 70 to 80 mile trip roughly. This is plenty plus climbing a 7% grade to get stable oil temperature reading. 

 

As for my weekend I've made two trips to McCall, ID on this tank of fuel. I'm only down 3/8 of tank at 300 miles. I'm really wanting to see the fill up numbers on this tank. I've got plenty of fuel to make the trip to Ontario, OR yet.

 

I've seen now another weird one which might bring the IAT back to the mix for Quadzilla. Like my trips to Ontario, OR start at 7:15am in the morning and the whole trip down is typically downhill following the Weiser River. There is several grades to climb over and drop into the next valley. Typically my oil temperature in the morning is a nice -15°F then by afternoon the temperature down in Ontario has been 100°F or better. Now the IAT rises up and the timing needs to retard some because oil temperature is up near matching each other. This remains the entire trip home. 

 

Morning temperatures here have been in the 50's most of the time a few mornings bottom of 60's. Like this morning was 59°F. The timing is a weebit too retarded in the cool morning and the oil temp remains cool sided. Now I'm trying to figure out the math to control timing and using IAT
 

 

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