Thermostatic lubrication system?

[Curious Kid]

Upon waking early this morning, the thought ocurred to me as to a design concept that works very much like that of a liquid cooled engine's cooling system. An external radiator wouldn't be neccessary unless increased heat rejection would be needed.

The idea is to have the system function as if having a smaller sump volume in that it has a rapid warm-up time, reaching running viscosity sooner leading to added fuel savings and potentially less mechanical wear. Once up to temp, that thermostat gradually enables full system circulation and thus providing greater dwell time for heat release and added additive resource.

 

[rpn453]

I don't think the cost and complexity to benefit ratio is low enough for that one.

 

[evoboy]

Ditto !! The reduction in oil capacity of modern engines is noticable , for this reason !! Modern engines have , mostly , been exhaustively tested & engineered to cope with the majority of operating conditions they will find themselves in. Your solution doesn't have a problem to solve !!! IMHO.

 

[GMorg]

The suggestion is interesting, but the sump oil does not represent a significant mass in the system. At startup, most of the waste heat is absorbed by the metal components. The thermal mass of the entire sump just is not enough to have a major impact on the time is take to heat the engine.

We have had similar questions where the suggestion is to run less oil so that it heats faster - small winter sump, large summer sump.

 

[eljefino]

When oil's cold & thick it gets pumped up to the head quickly enough but takes its time dripping back to the pan. If some bozo ran the car up to redline there wouldn't be very much extra oil available on such short notice.

 

[Gary Allan]

Quote:

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The suggestion is interesting, but the sump oil does not represent a significant mass in the system. At startup, most of the waste heat is absorbed by the metal components. The thermal mass of the entire sump just is not enough to have a major impact on the time is take to heat the engine.

We have had similar questions where the suggestion is to run less oil so that it heats faster - small winter sump, large summer sump.

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Well, I'd say that it depends on how you have it configured and whatnot. The oil temp tracks the thermal saturation of the engine, trailing the coolant by a good bit (as you asserted). So, you've got no "fuel mixture" advantage to heating the oil quicker. In my experience with exchangers, coolant warming can be delayed a bit with using it to heat the oil. You reach "para" (or psuedo) thermal saturation in a shorter time. You're effectively shunting the excess heat of the cooling jacket to the "other exit" that heat sees from the engine (other then the exhaust).

But we're looking at maximum fuel economy here ..and the sooner the oil is "at operating visc" the less btu's are going to be spent pushing glue.

There's no need for complicated systems here. You just have a 6 quart sump that operates on 2quarts at any one time ..and the same 2 quarts on startup.

I'm constructing a setup like that now. Unfortunately, I can't reduce my sump on an already designed engine. It's easy enough to make a 5 quart system act like a 5 quart system and have it be a 8-10 quart sump though. I can't see why it can't work the other way around.

Now making it practical for integration on a true "cost savings" my prove a challenge ..but stuff like that "coolant thermos" that they use on the hybrids can't have been considered simple.