OVERHEATING

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Dave999 said:
Thats fine I've read the advertising and the arguements for and against. some of it makes for compelling reading and some of it is the usual Ad. Man BS.
Just gotta chose which narrative you are swayed by... :) then try and find some solid science to back it up... and thats where the problems start, finding anything truely indpendent to back up or contradict the claims is nigh on impossible.

i can't find any good science to suggest its better and I can't find any good science to show its worse.

so it comes down to cost, availability and convienience. the first two are the killer for me.

Dave
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Ok, one more time. I use the term YOU in the general sense, not as in YOU personally.

You have a fixed cooling medium temperature to work with. That’s ambient temperature. So for ***** and giggles we’ll say that’s from about 20-110 degrees Fahrenheit.

That’s ALL you get.

Again, for ***** and giggles we’ll say you love to run your engine at 195 degrees.

Now we have the temperatures we are working with.

So, let’s say that it’s a 60 degree day and you are rolling down the road at 195 degrees. You have a 135 degree temperature difference between ambient and coolant temperature. Assuming you have a 195 degree thermostat it is partially closing at some points to maintain your 195 degree temperature.

On a 100 degree day, you now only have a 95 degree temperature difference. You have less ability to remove heat from the coolant. Now the thermostat is wide open all the time and the coolant temp climbs to 205 degrees because the ONLY thing the thermostat does is set the MINIMUM coolant temperature.

Now you come on here and say my engine overheats at 205 on hot days. One response is it’s not overheating. And that’s true. It’s isn‘t OVER heating but it’s too hot. IMO 195 is too hot for a performance engine but that’s another topic for another post. And you just don’t want the engine at 205 degrees.

The other stock in trade answer is what you gave. Slow the coolant down so it stays in the radiator longer. Obviously at first blush that makes perfect sense. But it’s DEAD wrong.

Since (in this example) we are dealing with a 95 degree temperature difference (I should be saying delta but you get the point) the longer the coolant stays in the radiator, the longer the coolant stays in the engine. And when the coolant stays in the engine longer, it picks up more heat. Since you only have a 95 degree temperature difference, the coolant staying in the radiator doesn‘t do a pinch of **** of good. In fact, it’s *** backwards.

Think it through. The coolant is in the block longer, so it picks up more heat. The radiator just can’t shed any more heat no matter how much longer the coolant stays in it because the difference in temperature between ambient and what is coming out of the engine isn’t enough to effect a coolant temperature change.

That’s exactly what happens and it shows up in the difference in coolant temperature at the gauge and the temperature rating of the thermostat.

If your cooling system is running at peak performance your temperature should be at or within 5 or no more than 10 degrees of what the thermostat rating.

How many times do we see guys running a 180 thermostat but the gauge (assuming the gauge is accurate) says 200??? All the time.

Thats an example of what happens when you don’t have enough air flow, coolant flow or both.

Again, thinking it through and now understanding that keeping the coolant in the radiator longer also means the coolant stays in the engine longer, collecting more heat we can now look at the other side of the equation.

We speed up the coolant (and if you are running a mechanical fan you are speeding up the fan too which is a GOOD thing most of the time) so that the coolant isn’t in the engine as long, and since it’s not in the engine as long the coolant has a lower temperature going to the radiator.

Now we give the radiator a better temperature difference (lower coolant temperature out of the block requires LESS heat to be removed by the radiator and ambient temperature) to allow the system to shed heat.

I can’t make it any more plain than that. Leaving the coolant in the radiator longer means that same coolant stays in the engine longer and therefore is picking up more heat that the radiator and ambient temperatures have to deal with.

If you are constantly running at ambient temperatures of say 80 degrees or lower then you can have more errors in the system and not pay for it.

But, if you don’t want 190 plus degree coolant temperatures (I don’t, it’s too hot for performance) then it’s even more critical to get the coolant out of the engine sooner to the temperature difference is as great as it can be.

We can’t control ambient temperatures but we can control how long the coolant stays in the engine, how big and how many (or how few) cores the radiator has and how fast we turn the water pump (which controls along with the thermostat how long the coolant stays in the engine and radiator) and all that controls the operating temperature of the engine.

So the TL;DR is speed up the coolant and let the thermostat set the minimum operating temperature and the radiator and ambient temperature control maximum operating temperature.
 
It's like I've tried my dangdest to explain before, 195 plus is just TOO hot because it leaves little to no room for error. But I get shot down every time. I want my junk running as cool as I can get it and then TUNE for it to run THERE. I don't know how cool Vixen runs. I have the factory C H temp gauge. lol But she never climbs above that first mark that's like 1/8 the way up. I would just guess she never sees 180 degrees and that's just fine with me.
 
If the thermostat opens at 180* true, and the coolant heat keeps climbing, then there isn't enuff cooling capacity, sure it'll creep up to 200, but it shouldn't.
If it creeps, something is deficient, and when you "work" the engine creating more heat, the temp will continue to rise till overheat.
Once the thermostat opens at whatever temp, that is the temp it should stay , uphill, in traffic, at a stoplite . .
 
The thermostat's specified temperature is the temperature that it is fully open. So that means if you have say a 180 thermostat, it STARTS to open at say 170 or possibly a little before and is fully open at 180. That's why to me, on a high performance build that sees more heat, it's important to run as cool of a thermostat as you can find for the given application and that's normally 160. The reason for that is, you want to curtail any extra heat before it starts happening. The cooler you can make one run, the less chance you have of over heating. It's just that simple. People who say things like "you create extra engine wear running it that cool" simply do not understand that you TUNE the engine to run at those temperatures. A true performance engine will never reach its full potential running 195 and above. It's just not going to happen.
 
RRR post #54,
The temp on the stat is the opening temp, not the temp when it is fully open. It takes another 20-30* to fully open.
So a 180 stat might not be fully open until 210*. Cheers.
 
Bewy said:
RRR post #54,
The temp on the stat is the opening temp, not the temp when it is fully open. It takes another 20-30* to fully open.
So a 180 stat might not be fully open until 210*. Cheers.
Click to expand...

Only for cheap thermostats. A quality thermostat will be fully open at its rated temp.

Junk is junk at any price.
 
Rat Bastid said:
Only for cheap thermostats. A quality thermostat will be fully open at its rated temp.

Junk is junk at any price.
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Yeah. Let um believe that garbage they've been ingrained with. All I know is my junk runs good.
 
Dana67Dart said:
RRR I hate to disagree but.... (You know me :rolleyes: )

Nascar run typically 230 to 260 deg F

And yes the engine clearances are tuned for that temp.

https://www.nascar.com/news-media/2014/06/14/debris-can-wreak-havoc-on-a-race-car/amp/


and they run that temp for hours.


the cooling system is also sized / setup for the heat being transfered.
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How big of a cooling system do you think it would take to cool an ASScar engine to say…160 degrees?

One it would be HUGE. That add weight. Plus the amount of air flow to run that temperature for hours on end would also be HUGE. That shoots the aero package right in the ***.

Just because ASScar or Pro Stock does something doesn’t mean it’s all applicable to what we do here. Pro Stock CHILLS the engine down to some crazy number. IIRC at the END of a pass they no hotter than 140 degrees.

Are they stupid? No. They KNOW cold engines and thin oil makes horsepower and they don’t need to worry about engine temps for 3-4 hours.

For a street driven engine 160 is about as hot as it should be. With that I can run far more compression than most guys even think of and not get into detonation.

Cold engines make power. To argue this is nonsense unless you are a classically trained engineer.
 
I worded post 53 poorly, my meaning is a 180* thermostat opening will fluctuate to maintain a 180 temp, not all open at 180, if it can't maintain 180 under load etc. something is deficient. Sorry for any confusion .
 
inertia said:
I worded post 53 poorly, my meaning is a 180* thermostat opening will fluctuate to maintain a 180 temp, not all open at 180, if it can't maintain 180 under load etc. something is deficient. Sorry for any confusion .
Click to expand...
No worries. Confusion is my normal state of mind. I'm used to it.
 
Mr bastid

i thought you were having a pop about evans coolant as i say i can't find anything either way to say if its good or bad and as i can't get it everywhere i choose not to use it

but now i see its about flow.. and you nearly have me convinced

I agree with what you say regarding temperature difference i.e the delta between ambient and coolant or indeed fin-surface on radiator. the bigger the gradient the more effective the radiator is at doing its job its all just balance, and heat energy spreads out from a place where it is concentrated to a place where it is less so like a drop of dye in a bucket of clear water.
i agree higher ambient temperature reduces the gradeint and yes you are more likley to overheat on a hot day due to this. this is obvious to all

BUT you arguemnt abount the coolant staying in the block too long only makes some sense if
the system is way under specification
if the system has the wrong rated cap
if the system is running pure water i.e boils at a temperature too low for the system it is being used as a coolant in

it doesn't properly take into account that fact that the system is presurised,
and if the coolant stays in the block longer and gets hotter as you state then the block and heads lost more heat eneregy from their surface to the coolant and the delta between the tmeprature of the coolant and the ambient temperature in the radiator again gets wider which make the effiiciency of the radiator better.... Up to a point. so slow is not neceesarily bad until one part of the system is way out of specification with the rest.

unlike the water in the bucket with a drop of dye, which will all end up slightly dyed the air flowing through the radiator has an infinte supply.... and as long as the temperature gradient stayes more or less the same the radiator works perfectly well and in a range of ambient temperaures.

if what you say is the case why did mopar put time and effort into producing a set-up for their race cars that slowed the pump down.... Thermo clutch fan, so i won't say slowed the fan down, as that would only be obvious, at, and just off idle and race cars don't idle.....
When they created engines with heads, induction and cam that moved the power and torque up the rpm range. i.e out of the range that the pump was designed for (grocery getting and freeway at 65 mph)

this was so that the pump turned at its optimum speed for best cooling. the pump has a sweet spot in the rpm range. its contsrained by its size position and shape. it pumps coolant of the kinda density you get with glycol and water at 16LB pressure 195F, the best at some RPM that is probably in the 2000 -3000 rpm range .

it needed to run at a speed that didn't cause cavitation and didn't, one presumes, pump the water round too fast. They must have found that too much pumping, a too high RPM at the pump had detrimetal impact on cooling.... maybe it didn't move the water faster, granted i could have the wrong end of the stick maybe , a too fast pump, just causes chaos and no pumping, but either way they spent money and time on working out that too fast at he pump impellor made the cooling worse

so my only crime is to assume that too fast pump=== too fast flow of water
and i'll agree that THAT may not be the case

so i agree with you on eveything apart from the bit about time in engine and radiator..i think there is more to it than either of us understand, but chrylser did, and changed the gearing on the pump to slow it down in cars that did the most work and created the most heat at an RPM that was greater than normal.

Dave
 
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Dave999 said:
Mr bastid

i thought you were having a pop about evans coolant as i say i can't find anything either way to say if its good or bad and as i can't get it everywhere i choose not to use it

but now i see its about flow.. and you nearly have me convinced

I agree with what you say regarding temperature difference i.e the delta between ambient and coolant or indeed fin-surface on radiator. the bigger the gradient the more effective the radiator is at doing its job its all just balance, and heat energy spreads out from a place where it is concentrated to a place where it is less so like a drop of dye in a bucket of clear water.
i agree higher ambient temperature reduces the gradeint and yes you are more likley to overheat on a hot day due to this. this is obvious to all

BUT you arguemnt abount the coolant staying in the block too long only makes some sense if
the system is way under specification
if the system has the wrong rated cap
if the system is running pure water i.e boils at a temperature too low for the system it is being used as a coolant in

it doesn't properly take into account that fact that the system is presurised,
and if the coolant stays in the block longer and gets hotter as you state then the block and heads lost more heat eneregy from their surface to the coolant and the delta between the tmeprature of the coolant and the ambient temperature in the radiator again gets wider which make the effiiciency of the radiator better.... Up to a point. so slow is not neceesarily bad until one part of the system is way out of specification with the rest.

unlike the water in the bucket with a drop of dye, which will all end up slightly dyed the air flowing through the radiator has an infinte supply.... and as long as the temperature gradient stayes more or less the same the radiator works perfectly well and in a range of ambient temperaures.

if what you say is the case why did mopar put time and effort into producing a set-up for their race cars that slowed the pump down.... Thermo clutch fan, so i won't say slowed the fan down, as that would only be obvious, at, and just off idle and race cars don't idle.....
When they created engines with heads, induction and cam that moved the power and torque up the rpm range. i.e out of the range that the pump was designed for (grocery getting and freeway at 65 mph)

this was so that the pump turned at its optimum speed for best cooling. the pump has a sweet spot in the rpm range. its contsrained by its size position and shape. it pumps coolant of the kinda density you get with glycol and water at 16LB pressure 195F, the best at some RPM that is probably in the 2000 -3000 rpm range .

it needed to run at a speed that didn't cause cavitation and didn't, one presumes, pump the water round too fast. They must have found that too much pumping, a too high RPM at the pump had detrimetal impact on cooling.... maybe it didn't move the water faster, granted i could have the wrong end of the stick maybe , a too fast pump, just causes chaos and no pumping, but either way they spent money and time on working out that too fast at he pump impellor made the cooling worse

so my only crime is to assume that too fast pump=== too fast flow of water
and i'll agree that THAT may not be the case

so i agree with you on eveything apart from the bit about time in engine and radiator..i think there is more to it than either of us understand, but chrylser did, and changed the gearing on the pump to slow it down in cars that did the most work and created the most heat at an RPM that was greater than normal.

Dave
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First off, go look at a factory service manual. Chrysler was OVERDRIVING the water pump on HP stuff. They didn’t do that because they were stupid.

Then think it through. The racers were slowing the pump down because they thought they were saving HP. They were not. All they did was make the cooling system less efficent. When you do that, you can’t run as much compression ratio, which means you buy fuel with higher octane and spend more money for it. Or, you pull timing to stop detonation. Or you add a bunch of fuel. All bad. So that theory is shot to ****.

I‘ve tested it on the dyno and in the world so many times I no longer bother with it. Cooler engine temps makes more power. Speeding up the pump makes it easier to cool the engine. I know this goes against your long held belief that slowing coolant down it what works, but it doesn’t.

I don’t use water or antifreeze on my performance junk. I use Evans. I know that pisses some off, but that tells me they didn’t test it. I know one media hack claims it doesn’t work (it does) and that it’s a fire hazard (its not) and uses all his verbal vomit to try and convince his sycophants that he is correct so they never test it.

It is expensive. So are my engines. Stepping over donuts to grab a turd isn’t my thing.

Using Evans coolant means the system doesn’t use pressure. That’s a huge BONUS. I shouldn’t have to explain that one to you.

Cavitation is an issue that isn’t just about pump speed. There is more to it than that. Why did Chrysler OVERDRIVE pumps? Because it COOLS better.

The only issue I find is if you are running a mechanical fan you need to watch fan speed. If you are shifting at 8500 you will probably need to slow the pump down (which slows down the fan) so it doesn’t **** the fan. Of course, if you are shifting at 8500 you probably aren’t running a mechanical fan.

It’s laughable that you wrote all that and still didn’t learn. You might THINK you know, but you are wrong to tell ANYONE to slow down the pump to help a cooling issue.

You will never be convinced of how wrong you are because it’s more important to you to hold onto a long held misbelief rather than learn the facts.

You NEVER slow down the pump to cure an overheating issue. You are wrong.
 
RustyRatRod said:
Stuck in the past is ok, too.
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No, no, not stuck in the past and not ignorant of tuning carburated cars with modern instrumentation. Clueless might be a better term to think that 195 F is too hot of a min operating temp for today's fuels. Ignorance is not an excuse but your case it is
 
SixPaksRule said:
No, no, not stuck in tha past and not ignorant of tuning cars with modern instrumentation. Actually i am very good at tuning and i have many clues as clueless might be a better term to think that 195 is too hot of a min operating temp for today's fuels. Ignorance is not an excuse.
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Well you tune your way and I'll tune mine. How bout that?
 
The thermostat stays closed to force the engine to warm up faster. It also "tries" to regulate the operating temp but often can't overcome too small of a radiator, a bad fan clutch or the like. Take the thermostat out and it takes forever to get to operating temp.
 
SixPaksRule said:
No, no, not stuck in the past and not ignorant of tuning carburated cars with modern instrumentation. Clueless might be a better term to think that 195 F is too hot of a min operating temp for today's fuels. Ignorance is not an excuse but your case it is
Click to expand...

I you think 160 is too cold for pump gas you are clueless on fuel and tuning.

So keep thinking you know what you know but you don’t know.

195 is too ******* hot for any performance engine. PERIOD.
 
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