How Much cooler will 30/70 run than 50/50?

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Sep 22, 2021
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I've got a modified 454 in my 69 Camaro and it runs a little warm. I've heard that if I changed the coolant mix from the over the counter 50/50 to 40/60 or even 30/70 with the adder being distilled water... it might run a little cooler. Has anyone ever experimented with cooling mixes alone and seen any gain? I know water is the best coolant on the planet, but I also know that coolant helps lubricate the system and has additives that will prolong the life of an engine and parts. And of course... it gives protection from freezing. My car is a 3 season restomod, it mainly sleep in the garage during the winter, and I only take it out after a good rain that washes away the salt. Temps in my garage have never gone below 15° and this car has never ever been left outside in all the years I've owned it. So a 30/70 mix won't give me -45° protection, but I think it'll be good to around -10°?

When I say warm, on an 85° day this summer running down the highway the temp gauge shows around 195-200. I have dual 12" eFans that are electronically controlled (PWM) to go on at 195°. I would like to get the temp down on the highway to around 190° so the fans will shut down and just let the 65 mph breeze do its job. If I get into traffic, the temp will go up to around 210-220 and stay there pretty much unless I can't move. The car has AC and air has to flow through the AC condenser and then through the radiator. One other alternative is to add a pusher fan out front, another is to find 2 new eFans that pull more air thru the fins. But before I spend more money on fans I want to think about the coolant mix.

Opinions?
 
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The operating temperature will be the same unless there is something wrong with your thermostat or your cooling system is compromised. The only way to lower the set point of the thermostat is to replace it with a different one.
 
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Wont be very noticeable. It could be a plus overall but you need other changes if you want it to run cooler.

What temp is your thermostat.
If you set your fans to come on a 200f would they turn off while highway cruising?

I dont see that as hot I see that as a setup that needs tweaking if it isnt doing what you want it to do.
 
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Hey mike! Since its a 69, I assuming you have no ECU. If that's the case, and you want it to run cooler, than change the thermostat down to a lower *, and change your fan setpoints lower also, for traffic situations.

I do not know how far down you can go before it has negative effects on the operation of the motor, but I have seen people run no thermostat before.
 
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The heat capacity of a 30/70 antifreeze mixture is approximately 10% higher than a 50/50 mixture, which is barely significant. Pure water has about 20% higher heat capacity than a 50/50 mixture. The metal temperature in the engine would theoretically run cooler with a weaker antifreeze mixture since the coolant would absorb more heat before it's temperature rose, but calculating how much cooler would probably take a super computer. Just a hunch, but I would bet that a 10 degree cooler thermostat would have more effect on engine metal temperature than a weaker antifreeze mixture.
 
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I've got a modified 454 in my 69 Camaro and it runs a little warm. I've heard that if I changed the coolant mix from the over the counter 50/50 to 40/60 or even 30/70 with the adder being distilled water... it might run a little cooler. Has anyone ever experimented with cooling mixes alone and seen any gain? I know water is the best coolant on the planet, but I also know that coolant helps lubricate the system and has additives that will prolong the life of an engine and parts. And of course... it gives protection from freezing. My car is a 3 season restomod, it mainly sleep in the garage during the winter, and I only take it out after a good rain that washes away the salt. Temps in my garage have never gone below 15° and this car has never ever been left outside in all the years I've owned it. So a 30/70 mix won't give me -45° protection, but I think it'll be good to around -10°?

When I say warm, on an 85° day this summer running down the highway the temp gauge shows around 195-200. I have dual 12" eFans that are electronically controlled (PWM) to go on at 195°. I would like to get the temp down on the highway to around 190° so the fans will shut down and just let the 65 mph breeze do its job. If I get into traffic, the temp will go up to around 210-220 and stay there pretty much unless I can't move. The car has AC and air has to flow through the AC condenser and then through the radiator. One other alternative is to add a pusher fan out front, another is to find 2 new eFans that pull more air thru the fins. But before I spend more money on fans I want to think about the coolant mix.

Opinions?
Those sound like normal temperatures to me. I think the radiator, fans, and thermostat have a larger impact than coolant mix.
 
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Efans are weak. A dual efan setup with the best electric fans on the market are only about half the CFM of a shrouded mechanical clutch fan. The party trick of efans is that they can be set to come on at lower temperatures and they have more airflow at idle.

A wetter coolant mixture will not make your cooling system radiate heat any better. What you have is a lack of dissipation. A 30/70 mix will simply take a little bit longer (un-noticable) amount of time to reach heatsoak. That's it.
 
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Two 12 inch fans don't move nearly enough air. The oe mechanical fan on say a 396 will move about 8000 cfm. What are the electric ones rated at?

Also the oe fan was at least 17 inches. Maybe bigger with a shroud to pull air through the entire core.

Not just 2 small spots. Often electric fans in this application become an air block @ freeway speeds. Leading to running hotter.
 
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The heat capacity of a 30/70 antifreeze mixture is approximately 10% higher than a 50/50 mixture, which is barely significant. Pure water has about 20% higher heat capacity than a 50/50 mixture. The metal temperature in the engine would theoretically run cooler with a weaker antifreeze mixture since the coolant would absorb more heat before it's temperature rose, but calculating how much cooler would probably take a super computer. Just a hunch, but I would bet that a 10 degree cooler thermostat would have more effect on engine metal temperature than a weaker antifreeze mixture.
Yes heat transfer is improved but that doesn’t result in a lower operating temperature unless the thermostat is already wide open.
 

BlueOvalFitter

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I've got a modified 454 in my 69 Camaro and it runs a little warm. I've heard that if I changed the coolant mix from the over the counter 50/50 to 40/60 or even 30/70 with the adder being distilled water... it might run a little cooler. Has anyone ever experimented with cooling mixes alone and seen any gain? I know water is the best coolant on the planet, but I also know that coolant helps lubricate the system and has additives that will prolong the life of an engine and parts. And of course... it gives protection from freezing. My car is a 3 season restomod, it mainly sleep in the garage during the winter, and I only take it out after a good rain that washes away the salt. Temps in my garage have never gone below 15° and this car has never ever been left outside in all the years I've owned it. So a 30/70 mix won't give me -45° protection, but I think it'll be good to around -10°?

When I say warm, on an 85° day this summer running down the highway the temp gauge shows around 195-200. I have dual 12" eFans that are electronically controlled (PWM) to go on at 195°. I would like to get the temp down on the highway to around 190° so the fans will shut down and just let the 65 mph breeze do its job. If I get into traffic, the temp will go up to around 210-220 and stay there pretty much unless I can't move. The car has AC and air has to flow through the AC condenser and then through the radiator. One other alternative is to add a pusher fan out front, another is to find 2 new eFans that pull more air thru the fins. But before I spend more money on fans I want to think about the coolant mix.

Opinions?
When I used to race, build engines, and hot rods, I would use Moroso water restrictors with a 40/60 (40% Green coolant 60% Distilled water). My dad showed me this trick. He used to race as well.
A cool can works too.
One more tip; do you index your spark plugs?
 
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When I used to race, build engines, and hot rods, I would use Moroso water restrictors with a 40/60 (40% Green coolant 60% Distilled water). My dad showed me this trick. He used to race as well.
A cool can works too.
One more tip; do you index your spark plugs?
Well, I learned something new today!! Thanks!

I do have a question about indexing the plug, how does help with cooling?
 

BlueOvalFitter

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Well, I learned something new today!! Thanks!

I do have a question about indexing the plug, how does help with cooling?
It doesn’t. Indexing will help with properly aligning the kernel created during the spark plug firing. It can change the power curve of the hp and torque.
The coolant restrictors are for a race engine not a street engine.
Lowering the percentage of anifreeze does effect the coolant temperatures as long as there is air flowing over the engine and radiator. Generally this can be empirically seen by about 2-4 degrees lower with a 70/30 mixture. The small amounts is why some that grab internet info and have not tried it will post it makes no difference .
All small amounts in any upgrade amount to larger numbers eventually. So if you add coolers and fans and if ECU change some PIDs you can lower the coolant be several degree or at least control specific ranges of concern .
 
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Do you have the fans mounted in a shroud that covers most of the radiator? If so it might be blocking airflow at highway speeds. I got the best cooling for my 1969 Charger .060 over 440 with flex-a-lite 17" nylon fan #116567. Yes it probably gave some HP at high RPM but car didn't get hot on the street. It had a 3 core 22" radiator with a homemade shroud. All of the edges were left open to allow airflow at highway speeds. 180° T-stat, cruising around town got up to 200 max, out on the highway it was against the T-stat at 180°. I never had real good luck with electric fans, so I just stayed with mech ones. The tech at Flex-a-lite told me to use the nylon fan, it moves more air than flex fans.................and you have to have at least 1.5" between rad core and front of fan or center of the fan will block air from going thru rad. Again this was from Flex-a-lite tech guys. It worked for me. I really needed a 2 core aluminum double pass 26" radiator, but that would've involved changing out the radiator support, which I didn't want to do at the time.

 
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You're temperatures don't seem that concerning.
50/50 coolant has boil protection to about 260F w/ 15psi cap.

I would not use water wetter. It is not really compatible with all coolants.

More water 60/40 70/30 will transfer heat better, but if you have a problem with your radiator it may not make a difference.
I would suggest trying this first. The additives should be sufficient until you get down below 70/30.
Feel free to read this:
 
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You're temperatures don't seem that concerning.
50/50 coolant has boil protection to about 260F w/ 15psi cap.

I would not use water wetter. It is not really compatible with all coolants.

More water 60/40 70/30 will transfer heat better, but if you have a problem with your radiator it may not make a difference.
I would suggest trying this first. The additives should be sufficient until you get down below 70/30.
Feel free to read this:
Plus it does nothing when used with a glycol/water mixture.
 
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