And that’s a good point. I’ve tried to find better data with no success. Two simple data points would be good. The kinematic viscosity of a synthetic 5w30 at -40 and the same for a synthetic 5w40. The same brand would make it even better.The graph is what exactly? Full-synth oil all by same maker, or something different?
Using the equation for hydraulic HP = Pressure (psi) x flow Q (gpm) ÷ 1714 gives (assuming following conditions and 100% efficiency).
At idle (30 psi, 2 gpm)
(30 x 2) ÷ 1714 = 0.035 HP = 26 watts
At 6000 RPM (70 psi, 8 gpm)
(70 x 8) ÷ 1714 = 0.327 HP = 244 watts
Assuming 80% pump efficiency, then:
At idle, 32.5 watts to pump 2 gpm at 30 psi.
At 6000 RPM, 305 watts to pump 8 gpm at 70 psi.
Good point. Here is an expanded version of the J300 chart. To qualify as a 5W, the oil has to have a MRV ( mini-rotary viscometer) reading of 60,000 cP or less. That is easy to meet with modern 5W oils. In fact, here is data from Mobil for their 5w30 and a 5w40. Have a look at the MRV for each. Also, notable is the the MRV for their 5w30 is much less than the MRV for their 5w40, but both are much less than 60,000 cP required by the SAE J300 requirements. Enjoy.when it comes to cold temp performance, has the technology reached a plateau?
any significant improvements in regard to mrv and ccs in the past 5 years?
sounds like pour point is not very relevant in the presence of mrv.
The oil pump output pressure and flow is determined by: 1) The oiling system total flow resistance, 2) The oil viscosity and 3) The pump performance curve based on pump design & engine RPM.The question is, where do you reach a certain psi. With a lower viscosity oil, it will be at a higher rpm. Stone cold it makes no difference, but somewhere in the warmup phase it will, and it certainly will when hot.
Here is some info on the Mini Rotary Viscometer and the Cold Cranking Simulator. Yes, a bit more sophisticated than an orifice.Isn't the puzzle a titch simpler than all of this belly button gazing?
I thought, honestly up to this point; that the so called "W' rating was simply determined by a certain volume of ice cold oil flowing through a known, standardized orifice bore diameter with the pull of gravity...Vs. time.
Am I hopelessly daft on this point?
Yes, there are usually no data points in between the CCS combined with the MRV, and the kinematic viscosity at 40 C. That a gap from around -35 C to plus 40 C. But really, the oil passes through all of this in 10 to 15 minutes.key point being that the winter rating is only valid at the test temperatures. For the rest we have to depend on the summer rating and the viscosity index. Viscosity index most often tracks the winter rating though, but that's not necessarily always so.
Figures 5 and 6 in the paper link shows around 700 watts in Fig 6 just before the 20 min mark, and the corresponding graph in Fig 5 shows at that's occurring at ~3800 RPM with the oil at ~90C. Could also be that oil pumps are not that efficient at pumping (worse than 80% as assumed). In Figure 11 they show a fixed displacement PD pump taking ~270 watts (maybe that's some kind of average in normal usage at lower RPM-?), so numbers seem to be all over the place. Anyway, interesting papers ... thanks for the links.I got them from a LUK presentation on oil pumps.
But I read it wrong I think...
... is there anyway you can make the whole graph and table show up without having to use the horizontal slider?It is now working properly, although the format is not finished yet (size)