![]() | #4126 | ||
Distinguished - BHPian ![]() | ![]() Quote:
Quote:
Modern car engine cooling system are typically closed system. As per my earlier post, as the engine and the cooling system heats up, the volume of the coolant expands. As the system is a closed one, the pressure builds. At this higher pressure the coolant, or any liquid for that matter, boils at a higher temperature. Adding coolant to water ensures an even somewhat higher boiling temperature. Effectively requiring a little less pressure! But the coolant is there for more important reasons as well, e.g. protection of your cooling system against corrosion, ensuring it doesn't freeze below zero degree C and it also help lubricate the water pump. But the density of the coolant mix or percentage doesn't determine the actual coolant pressure. Physics simply don't work that way. Jeroen | ||
![]() | ![]() |
|
![]() | #4127 | |
BHPian Join Date: May 2013 Location: shimla
Posts: 276
Thanked: 311 Times
| ![]() Quote:
1) Coolant system design, especially the size of hozes and pipes 2) Physical properties of fluids including density(will elaborate more on that) 3) Operating temperature I am stating that the system pressure will depend on density partly due to my experience with designing and operating industrial pumping curcuits. There is a continuous flow of coolant+water in the circuit. This is achieved by the water pump. This pump is a centrifugal pump and the pressure developed by this pump in a closed loop circuit is dependent on the resistance in the circuit(narrower hoses=more resistence=higher pressures) and density of the fluid being pumped. Simply put a pump requires to put out more pressure for a denser fluid(coolant is denser than water). Hence I state that increasing the coolant/water ratio will do the following things 1) Increase system pressure due to higher density 2) Ensure it doesn't freeze below zero degree C 3) Increase the boiling point 4) Presence of coolant aids in pump lubrication and prohibits corrosion 5) lower the heat carrying capacity of the system as coolant is not as good a heat transfer agent as water We have changed an engine oil discussion into something completely different. Mods will not be pleased ![]() Last edited by mobike008 : 8th September 2014 at 15:34. Reason: pls dont quote entire post while replying... | |
![]() |
![]() | #4128 | |
Distinguished - BHPian ![]() | ![]() Quote:
Density has no effect on either the volumetric flow rate or the head developed by a centrifugal pump. This essentially means that for a given volume flow rate a change in density will change the mass flow rate. Thus if the density increases the mass flow rate will increase and if the density decreases the mass flow rate will decrease. The most immediate noticeable effect of density change if you are not measuring the mass flow will be in the absorbed power of the pump driver. This is evident from the absorbed power equation for any pump. P = Q*H*ρ*g / 3600*η where: P = absorbed power, kW Q = volumetric flow rate, m3/h H = Differential head, m ρ = density of liquid, kg/m3 g = gravitational constant , 9.81 m/s2 η = efficiency, dimensionless So please share how density affect pressure. I'm aware that a lot of people talk about designing pumps, but what they are doing is sizing a pump for a particular application. That is not designing. There are simple tables and graphs for that, usually based on water and often showing specific gravity. Those tables might give the impression of the pressure raising. But what effectively happens is you need to put more power on the pump to maintain the same flow. The power for your typical water coolant pump in a car engine is not a factor. The pump is driven directly from the engine. So whatever RPM and whatever density that's the power that the engine will put into the pump so to speak. Do you really design pump? What firm, what kind of pumps and applications If you do I might have a few more questions for you. Just show me some evidence to the contrary to what I just said. In reality we are talking about a minimal change of density too. At a 50/50 mix of coolant (glycol) and water the density increase is approx 8%. Jeroen | |
![]() | ![]() |
![]() | #4129 | |
BHPian Join Date: May 2013 Location: shimla
Posts: 276
Thanked: 311 Times
| ![]() Quote:
P=head *density*gravity. So the discharge pressure of the pump will be 1+10=11 bar gauge. Now if I replace this water with a fluid of density 20 percent more than water and as long as the fluid is not very viscous, the pump will still produce 100 m head at same volumetric flow rate. but the pressure increase due to pump in this case will increase by a factor of 1.2 to 12 bar approximately using p=head*density*gravity since density has increased by 20 percent. So discharge pressure will be 1+12=13 bar gauge So a density increase has changed the discharge pressure of the pump. Power consumed will also be higher as per your formula. Similarly if u use a lighter fluid say petrol or kerosene with density lesser than water with this fictitious pump discharge pressure will be lower and power consumption will also be lower. Last edited by bullrun87 : 8th September 2014 at 15:41. | |
![]() |
![]() | #4130 | ||
Senior - BHPian ![]() | ![]() Quote:
Quote:
When I rang up my S.A. in Ford A.S.S, they said they had it in stock and would cost Rs 1200 per liter, which seemed to be a lot cheaper, as my car needed 4.1 liters. I gave one final try and called Xenex. They said they'd deliver it at home for a price of Rs 1000 a liter, but I'd have to buy 4.5 liters as it comes in 3.5 liter and 1 liter packs. Though I needed less than that, I thought it would be a good idea to keep some for future top ups. Xenex also said that according to the Mobil1 rep in Hyd, the same oil is sold as 5W50 for Porsche and as 5W40 for Skoda. I find this quite intriguing, moreso when their website only mentions 5W50 and OW40. Users of Mobil1 may please update this thread on what they paid per liter. | ||
![]() |
![]() | #4131 | |
Senior - BHPian ![]() Join Date: Mar 2005 Location: Chandigarh/Mohali/Ambala Cantt
Posts: 3,820
Thanked: 1,948 Times
| ![]() Quote:
I tried looking around 5W50; but was not able to find it. Finally settled for 0W40 at 950/L. I would recommend that you go in for 0W40. | |
![]() | ![]() |
![]() | #4132 | |
Senior - BHPian ![]() | ![]() Quote:
| |
![]() |
![]() | #4133 | |
Senior - BHPian ![]() Join Date: Mar 2005 Location: Chandigarh/Mohali/Ambala Cantt
Posts: 3,820
Thanked: 1,948 Times
| ![]() Quote:
Mobil 1 and Delvac 1 are the best in their respective segments. | |
![]() | ![]() |
|
![]() | #4134 | |
Distinguished - BHPian ![]() | ![]() Quote:
Jeroen Last edited by Jeroen : 9th September 2014 at 19:40. | |
![]() |
![]() | #4135 |
Senior - BHPian ![]() Join Date: Mar 2005 Location: Chandigarh/Mohali/Ambala Cantt
Posts: 3,820
Thanked: 1,948 Times
| ![]() |
![]() |
![]() | #4136 | |
Distinguished - BHPian ![]() | ![]() Quote:
The head of a pump in metric units can be expressed in metric units as: h = (p2 - p1)/(ρ g) + v2(2)/(2 g) where h = total head developed (m) p2 = pressure at outlet (N/m2) p1 = pressure at inlet (N/m2) ρ = density (kg/m3) g = acceleration of gravity (9.81) m/s2 v2 = velocity at the outlet (m/s) Also, the pressure in an engine's cooling water circuit is rarely higher then 1 bar. So from a practical point of view, for car engines at least, this effect is negligible I would say. | |
![]() |
![]() | #4137 | |
Distinguished - BHPian ![]() | ![]() Quote:
So what is the performance then? How did you measure the performance during the 2L kms? Jeroen | |
![]() |
![]() | #4138 | |
Senior - BHPian ![]() Join Date: Mar 2005 Location: Chandigarh/Mohali/Ambala Cantt
Posts: 3,820
Thanked: 1,948 Times
| ![]() Quote:
When i said performance over 2L kms; i didn't go around measuring clearances and other parameters. I was just quoting the usual NVH levels and engine behavior. | |
![]() | ![]() |
![]() | #4139 | |
BHPian Join Date: May 2013 Location: shimla
Posts: 276
Thanked: 311 Times
| ![]() Quote:
| |
![]() |
![]() | #4140 | |
Distinguished - BHPian ![]() | ![]() Quote:
Truth be told, any car engine, properly looked after, properly maintained in accordance with the manufacturers specifications and using oil in accordance with the recommended specification will all run 2L ams without issues relating to oil. Given that I assume everybody puts the correct spec oil in their engines, and don't take notice of people on the internet who advise differently, the most prominent factors in engine wear, much more prominent then the oil, are: - Correct oil filtrations (i.e. the correct filter and changed at the correct intervals) - Correct air filtration (i.e. the correct filter and changed at the correct intervals) - Ensuring the cooling system works correctly, especially avoiding too low temperatures due to faulty thermostats etc. - Engine use, (e.g. city versus highway etc) As long as you use the correct specification of oil, the brand doesn't matter much. At least not in practical terms. Other factors, as mentioned above are far more important. Surprisingly, on car forums everybody seems to want to debate endlessly what is really not a big factor. But I'm not complaining. I never buy new cars, so the more money gets spend on the cars by their first/second/third owner before I would buy it the more beneficial it is to me. This is another consideration I don't hear much about. If you replace your car every say 5 years or at 100 or 150.000 kilometers, how relevant is the oil quality then? Again, the answer is, as long as the oil complies with the manufacturers recommendation it is very likely not very relevant for the owners during that first 100-150K. It becomes relevant for the next 100-150K. Jeroen | |
![]() | ![]() |