Cooling info, Don't beleive the hype!!
08-06-04, 01:58 PM
#52
Lives on the Forum
Originally Posted by paw140
Propylene glycol, not polyethylene glycol. HUGE difference.
http://www.evanscooling.com/main21.htm
https://www.rx7club.com/showthread.p...ighlight=evans
Last edited by SleepR1; 08-06-04 at 02:04 PM.
08-06-04, 05:28 PM
#53
Rotary Enthusiast
Originally Posted by DamonB
Even if you are comparing two disimilar fluids? If you're measuring your temps inside the engine block and all else is the same except for differing fluids and one fluid runs hotter at the point where heat is absorbed (inside the engine) then isn't one fluid hotter due to its ability to extract more heat from the motor?
How could it be otherwise?
How could it be otherwise?
so for a pound of fluid: dT = btu / sh
per evans website, adjusted for density, 50/50 has 22% higher specific heat rating, and water has 40% higher. if the same volume of each fluid, with same initial temperature, removes the same amount of heat from the chambers, the npg+ will have the highest temperature rise, removing the same heat energy.
if the volume of NPG+ rose 10F, the 50/50 would rise 8F, and the water 7F, removing the same amount of heat in each case.
That assumed each fluid sucked up the same heat. That quality is based on the overall heat transfer efficiency of each fluid. The 2 main properties that improve this are low viscosity, and high thermal conductivity. NPG+ is better than the old NPG, but both viscosity and thermal conductivity are better for 50/50, and best for water.
Is NPG+ then bad? no. it's just not the magical fluid most think it is.
For identical cars, when the heat load is low, the t-stat and fans will keep temps similar to a 50/50 system with a working 15 psi cap. at the road-track, with t-stat wide open, a 50/50-15 psi system will keep the engine and oil cooler, up to some hp limit where the bulk coolant temp rises to about 240F. This is when the bulk coolant temp is too close to the boiling point, and the bubbles don't condense, and heat transfer takes a nose dive and the gage starts going up rapidly. At this same threshold load, the npg+ will be hotter and so will the metal parts, but not even close to boiling. And, if your typical leaky cap drops the 50/50 system pressure to zip, the boiling point just dropped from 265F to 225F, so your new limit temperature is only about 200F.
That's why npg+ is good ... doesn't rely on pressure to raise boiling point by 40F, and doesn't boil.
08-06-04, 08:00 PM
#54
Lives on the Forum
Originally Posted by KevinK2
specifc heat rating for each fluid: heat (btu's) required to raise the temperature of 1 lb of the fluid 1 deg F.
so for a pound of fluid: dT = btu / sh
per evans website, adjusted for density, 50/50 has 22% higher specific heat rating, and water has 40% higher. if the same volume of each fluid, with same initial temperature, removes the same amount of heat from the chambers, the npg+ will have the highest temperature rise, removing the same heat energy.
if the volume of NPG+ rose 10F, the 50/50 would rise 8F, and the water 7F, removing the same amount of heat in each case.
That assumed each fluid sucked up the same heat. That quality is based on the overall heat transfer efficiency of each fluid. The 2 main properties that improve this are low viscosity, and high thermal conductivity. NPG+ is better than the old NPG, but both viscosity and thermal conductivity are better for 50/50, and best for water.
Is NPG+ then bad? no. it's just not the magical fluid most think it is.
For identical cars, when the heat load is low, the t-stat and fans will keep temps similar to a 50/50 system with a working 15 psi cap. at the road-track, with t-stat wide open, a 50/50-15 psi system will keep the engine and oil cooler, up to some hp limit where the bulk coolant temp rises to about 240F. This is when the bulk coolant temp is too close to the boiling point, and the bubbles don't condense, and heat transfer takes a nose dive and the gage starts going up rapidly. At this same threshold load, the npg+ will be hotter and so will the metal parts, but not even close to boiling. And, if your typical leaky cap drops the 50/50 system pressure to zip, the boiling point just dropped from 265F to 225F, so your new limit temperature is only about 200F.
That's why npg+ is good ... doesn't rely on pressure to raise boiling point by 40F, and doesn't boil.
so for a pound of fluid: dT = btu / sh
per evans website, adjusted for density, 50/50 has 22% higher specific heat rating, and water has 40% higher. if the same volume of each fluid, with same initial temperature, removes the same amount of heat from the chambers, the npg+ will have the highest temperature rise, removing the same heat energy.
if the volume of NPG+ rose 10F, the 50/50 would rise 8F, and the water 7F, removing the same amount of heat in each case.
That assumed each fluid sucked up the same heat. That quality is based on the overall heat transfer efficiency of each fluid. The 2 main properties that improve this are low viscosity, and high thermal conductivity. NPG+ is better than the old NPG, but both viscosity and thermal conductivity are better for 50/50, and best for water.
Is NPG+ then bad? no. it's just not the magical fluid most think it is.
For identical cars, when the heat load is low, the t-stat and fans will keep temps similar to a 50/50 system with a working 15 psi cap. at the road-track, with t-stat wide open, a 50/50-15 psi system will keep the engine and oil cooler, up to some hp limit where the bulk coolant temp rises to about 240F. This is when the bulk coolant temp is too close to the boiling point, and the bubbles don't condense, and heat transfer takes a nose dive and the gage starts going up rapidly. At this same threshold load, the npg+ will be hotter and so will the metal parts, but not even close to boiling. And, if your typical leaky cap drops the 50/50 system pressure to zip, the boiling point just dropped from 265F to 225F, so your new limit temperature is only about 200F.
That's why npg+ is good ... doesn't rely on pressure to raise boiling point by 40F, and doesn't boil.
08-13-04, 03:33 PM
#55
Originally Posted by Str8Down
So I flushed the system and refilled with 100% distilled water, just because everyone I came across on the board says that water cools better that antifreeze/coolant. Well, shortly after that I got a PFC so I can now monitor my temps. On 90+ degree days, driving home from work in bad stop and go traffic with the AC on, I was seeing temps as high as 108C.
So just be careful what you read here and don't take it as the bible. Many may come in here and still swear that water cools better than coolant, but I will never beleive it again, because I have seen it with my own eyes now.
But the cooling system on cars are not designed to run at 54 psi as in a Formula 1 car so you end up having to mix EG to prevent mass boiling till 285F.
What the above boils down to is that there is an interplay b/w:
1. thermal conductivity of each substance,
2. its boiling point depending on pressure
3. thermal mass
4. design of the cooling system.
There are alot of ignorant people around, they take one sound bite (water is the best coolant; Saddam had WMDs) and then bet their farm on it.
Educate yourself and think for yourself. Don't let others do your thinking for you.
08-13-04, 07:46 PM
#56
2/4 wheel cornering fiend
Originally Posted by pomanferrari
There are alot of ignorant people around, they take one sound bite (water is the best coolant; Saddam had WMDs) and then bet their farm on it.
Educate yourself and think for yourself. Don't let others do your thinking for you.
Educate yourself and think for yourself. Don't let others do your thinking for you.
08-13-04, 09:56 PM
#57
Originally Posted by Kento
Thus one of the greater problems of this young internet generation....
I don't think it's just this generation.
Take any generation: 50 years ago, we put Americans who looked like the enemy into concentration camp b/c of the justification that it's war time and that just b/c these Americans look like the enemies, they must be the enemies.
The really cruel thing was they didn't throw all the Germans and Italians into concentration camps.
People of conscience didn't speak out b/c they let others think for them.
I wouldn't be surprised if they throw a whole group of people into concentration camps again just b/c those people looked like the enemies.
Damn, I'm off topic again.
Last edited by pomanferrari; 08-13-04 at 10:01 PM.
08-13-04, 10:29 PM
#58
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any info on how well evans lubes the water pump seal etc. that is one of the purposes of the coolant also. does it have any rust inhibitors? anything to deal with the dissimalar metals in the engine? or is the electrolisys reduced because of the lack of water?
08-17-04, 09:56 AM
#59
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Originally Posted by mad_7tist
any info on how well evans lubes the water pump seal etc. that is one of the purposes of the coolant also. does it have any rust inhibitors? anything to deal with the dissimalar metals in the engine? or is the electrolisys reduced because of the lack of water?
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