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What's wrong with measuring something at its hottest point? If your gauge never goes above 250 or so in the sandwich plate, would it not be safe to say the pan will be the same or cooler?
Has someone said that measuring the oil at the (suspected) hottest point is not theoretically optimal?
For most of us, I think that practicality (in terms of ease of installation) is probably the key factor, mostly because we're interested in trends (is the engine running hotter / colder today than usual?) rather than in using highly accurate instruments to establish precise, exact measurements.
That being said, it would be interesting to see someone instrument an engine with oil temp sensors in multiple locations, and compare them (using sensors and gauges of higher-than-Autometer precision, of course.) I, for one, would love to see comparative, simultaneous measurements of the oil in the pan, the oil at the filter (before the cooler), the oil after the cooler, and the oil in some location after it's passed through the majority of the engine I'm not sure if there's a passage in the head which is easily instrumented in a location that isn't a dead-end. Maybe drill a tiny hole into one of the galley plugs and pass a K-type thermocouple through it.
But I'm diverging from the practical into the academic here...
Originally Posted by Savington
...and 15w50 in built engines (specifically, in any engine with a non-stock bearing package).
Has someone said that measuring the oil at the (suspected) hottest point is not theoretically optimal?
Originally Posted by Savington
The oil pump adds more heat to the oil than any other component in the engine. Measuring at a sandwich plate is a fool's errand. Measure at the sump or don't bother.
I agree with you Joe. Most of use are just looking to for changes in setups or watching for issues. Trying to compare values to anyone is the internet is always a crap shoot because there are so many factors. Accuracy of the sender, accuracy of the gauge, location of the sender, etc.
The purpose of the paper is to present the friction benefits of adopting roller bearings instead of flooded bearings for the crankshaft (i.e., Porsche 356 Carrera). The test engine was a Euro Ford 1L Ecoboost engine. Section V contains some interesting measurements where the stock engine was powered externally to determine torque consumption of various subsystems. The graphs are a bit hard to interpret because they are scaled in %Torque, which would necessarily be an increasing absolute torque value (somewhat linear?) with increased RPM. In any case, here's the graph:
There aren't any real surprises here. The main %Torque consumer at all tested RPMs is the pistons/conrods. Next in line depends upon RPM. The %Torque consumed by the crankshaft steadily increases with RPM and, if the engine had been spun to a higher RPM, would have become the main consumer (not a surprise to anyone familiar with ARPs "Reciprocating Weight vs. RPM" graph -- https://arp-bolts.mobi/p/tech.php?page=2). At 6000RPM, it was second behind the pistons/conrods.
To Andrew's point, the oil pump was a consistently heavy %Torque consumer with a more-or-less stable percentage across the RPM range. At low RPM, the oil pump consumed more %Torque than the crankshaft. This relationship reversed around 4000RPM.
The valvetrain was interesting, as it represented a decreasing share with RPM. The Ecoboost uses roller lifters, so I'm not sure how well this relates to the Mazda B.
Incidentally, "FEAD" means "Front End Accessory Drive." I had to look that up.
I suspect most people are looking for validation that their oil temps are in line with what the larger automotive industry as a whole deems to be acceptable. To that end, measuring the oil temp in the same place that the industry does becomes quite important. If you measure at the sandwich plate pre-cooler and get a temp of 280*F, but the sump temp is 240*F, and the industry says that a sump temp of 240*F is perfectly acceptable given the oil you are using, then you might spend an awful lot of money to solve a problem which doesn't actually exist.
To Andrew's point, the oil pump was a consistently heavy %Torque consumer with a more-or-less stable percentage across the RPM range. At low RPM, the oil pump consumed more %Torque than the crankshaft. This relationship reversed around 4000RPM.
Nice find. I wonder if the rings and pistons contribute a higher share of the friction torque, but less of that friction (heat) is shed into the oil since the oil doesn't come into contact with the pistons/rings nearly as much as it comes into contact with the oil pump?
Nice find. I wonder if the rings and pistons contribute a higher share of the friction torque, but less of that friction (heat) is shed into the oil since the oil doesn't come into contact with the pistons/rings nearly as much as it comes into contact with the oil pump?
I would suspect so. In particular, there is a heat path to the cylinder block water passages for the pistons and rings. So the heat from that friction would be absorbed by both oil (in the bearings) and water (cylinder walls). OTOH, the crankshaft and oil pump would reject their friction heat almost exclusively to the oil.
They are seeing overall efficiency gains in the 3-6% range, but yes, if you decouple the dominant source of friction in the engine (pistons) from the heat-to-oil calculation (which is obvious, but I hadn't realized the magnitude of this contribution to overall friction), then 3-6% overall starts to become meaningful in the context of heat-to-oil.
I wonder how they are breaking down "crankshaft and seals" and "pistons and conrods". I assume that the rings are included in the pistons/conrods section, and I also assume that the *vast* majority of the friction created is by the rings, as the pistons should technically never actually contact the cylinder block during normal operation (or at least no more so than the bearings contact the crank). I do wonder if the rod bearings are included in the "crank" or the "conrods" category, and how much of that friction is due to windage losses from the physical crankshaft itself and how much is due to the friction in the bearings themselves (I know the frictional losses to the seals are extremely minimal).
Given that the analysis was subtractive (measure the load, remove a part, and then re-measure the load, then remove another part, etc), I think we can assume that windage losses were accounted for. As these include both the air contact with the rotating assembly as well as pumping losses on the underside of the piston, it seems safe to assume that the rings themselves constitute a vast majority of the combined pistons / conrods / crankshaft friction figure.
On the other hand, these losses are still friction, they still generate heat, and it's reasonable to postulate that at least some of that heat is going to be absorbed by the oil. (Much of it will, of course, be vented by the PCV system, and absorbed into the structure of the block and, therefore, the water jacket.)
04-23-2019, 04:41 PM
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