440 heating only on highway speeds

[Torky]

hey guys,

my 1973 challenger 440 auto goes upto 210 - 220 only if driving at 3000 rpms constant on the highway , comes down when driving normal / stuck in traffic, 4 core rad , high flow dual fans , high flow waterpump , 180 thermostat
i live in qatar and the weather here is 110f or so , it that normal and alright? when the weather gets down to 95 100 she runs a steady 180 -200 , she has never puked over or anything.

built 440 - dont know specs but she idles at 950 , 7.5 inch of vacuum at idle - mean idle .

Let me know guys

You might check ignition timing and advance. I've also read extensively, and as a mechanical engineer I believe, that water pump and radiator must be designed to work with each other-lest coolant flow through the radiator too fast to lose its heat-seriously! I'm suspicious that the high flow pump might be doing just that at the elevated pump RPM at high speed.

 

[josephqatarcarguy]

Would you consider a move to Antarctica ? A little cooler climate than your area.

HAHAHA I wouldnt mate cause the girls come easy and the dr*gs come cheap and we make the benjamins!!!!!

 

[WileE]

HAHAHA I wouldnt mate cause the girls come easy and the dr*gs come cheap and we make the benjamins!!!!!

I'll take the first, and the last.

 

[Jeff Peterson]

I've also read extensively, and as a mechanical engineer I believe, that water pump and radiator must be designed to work with each other-lest coolant flow through the radiator too fast to lose its heat-seriously! I'm suspicious that the high flow pump might be doing just that at the elevated pump RPM at high speed.

Debunking the I Can Have It Both Ways Theory​

The water has to have "time to cool" argument is perhaps the most common one we hear. In a closed loop system if you keep the fluid in the heat exchanger you are simultaneously keeping it in the block longer. Unfortunately, the block is the part that is generating the heat and the radiator is the part that is shedding it. Sending hot coolant from your source (engine) through the heat exchanger (radiator) to the sink (air) will always transfer heat as long as there is a temperature difference between the source and sink. The more times you introduce the source to the sink the greater chance you have to shed the heat out of the closed loop system.

 

[Cranky]

Would you consider a move to Antarctica ? A little cooler climate than your area.

 

[68-500]

Debunking the I Can Have It Both Ways Theory​

The water has to have "time to cool" argument is perhaps the most common one we hear. In a closed loop system if you keep the fluid in the heat exchanger you are simultaneously keeping it in the block longer. Unfortunately, the block is the part that is generating the heat and the radiator is the part that is shedding it. Sending hot coolant from your source (engine) through the heat exchanger (radiator) to the sink (air) will always transfer heat as long as there is a temperature difference between the source and sink. The more times you introduce the source to the sink the greater chance you have to shed the heat out of the closed loop system.

As I always suspected!

 

[Cranky]

Debunking the I Can Have It Both Ways Theory​

The water has to have "time to cool" argument is perhaps the most common one we hear. In a closed loop system if you keep the fluid in the heat exchanger you are simultaneously keeping it in the block longer. Unfortunately, the block is the part that is generating the heat and the radiator is the part that is shedding it. Sending hot coolant from your source (engine) through the heat exchanger (radiator) to the sink (air) will always transfer heat as long as there is a temperature difference between the source and sink. The more times you introduce the source to the sink the greater chance you have to shed the heat out of the closed loop system.

Have you ever ran an engine without a thermostat? I have and it ran hotter than it did with one. Looks to me that the coolant can flow too fast and the thermostat acts as somewhat of a restriction? Now on my beater Dakota, the thermostat seems to be stuck as the temp never does come up very fast and it really never does come up to regular temp in the winter time. If the coolant runs too fast through the engine and radiator, it won't pick up the heat from the engine and won't cool off much once in the radiator but will keep on picking up heat each time the coolant goes through the engine but will sluff off less as it goes through the radiator. Now if the radiator is super big, it will cool the coolant. Seems that my beater got a large core (albeit a single core) radiator that is very efficient that keeps it cool even on those 105 degree days that we sometimes get here.

 

[Jeff Peterson]

Have you ever ran an engine without a thermostat? I have and it ran hotter than it did with one. Looks to me that the coolant can flow too fast and the thermostat acts as somewhat of a restriction? Now on my beater Dakota, the thermostat seems to be stuck as the temp never does come up very fast and it really never does come up to regular temp in the winter time. If the coolant runs too fast through the engine and radiator, it won't pick up the heat from the engine and won't cool off much once in the radiator but will keep on picking up heat each time the coolant goes through the engine but will sluff off less as it goes through the radiator. Now if the radiator is super big, it will cool the coolant. Seems that my beater got a large core (albeit a single core) radiator that is very efficient that keeps it cool even on those 105 degree days that we sometimes get here.

That's because you have no pressure differentiation, just like what happens when you have a bad cap that won't hold pressure.

 

[Cranky]

That's because you have no pressure differentiation, just like what happens when you have a bad cap that won't hold pressure.

It builds pressure.....just not as much since the coolant isn't up to standard temp.

 

[Jeff Peterson]

It builds pressure.....just not as much since the coolant isn't up to standard temp.

It may build pressure but, it's equal between the engine and radiator with no thermostat.

 

[Cranky]

It may build pressure but, it's equal between the engine and radiator with no thermostat.

I'm guessing I'm not understanding......when the stat is open, isn't the pressure the same in both the engine and rad? I did mention not running one and my temp was higher but that was the only time to run without one.

 

[RJRENTON]

Have you ever ran an engine without a thermostat? I have and it ran hotter than it did with one. Looks to me that the coolant can flow too fast and the thermostat acts as somewhat of a restriction? Now on my beater Dakota, the thermostat seems to be stuck as the temp never does come up very fast and it really never does come up to regular temp in the winter time. If the coolant runs too fast through the engine and radiator, it won't pick up the heat from the engine and won't cool off much once in the radiator but will keep on picking up heat each time the coolant goes through the engine but will sluff off less as it goes through the radiator. Now if the radiator is super big, it will cool the coolant. Seems that my beater got a large core (albeit a single core) radiator that is very efficient that keeps it cool even on those 105 degree days that we sometimes get here.

Debunking the I Can Have It Both Ways Theory​

The water has to have "time to cool" argument is perhaps the most common one we hear. In a closed loop system if you keep the fluid in the heat exchanger you are simultaneously keeping it in the block longer. Unfortunately, the block is the part that is generating the heat and the radiator is the part that is shedding it. Sending hot coolant from your source (engine) through the heat exchanger (radiator) to the sink (air) will always transfer heat as long as there is a temperature difference between the source and sink. The more times you introduce the source to the sink the greater chance you have to shed the heat out of the closed loop system.

Not true....please show us all your calculations included flow velocity and temperature differences both in/out of engine AND radiator....for a given RPM to balance the volume calculations...(realizing that pump volume varies with pump rpm) and the specific heat characteristics of the choosen coolant. The greater delta T between the air and coolant, the more heat is exchanged....in Btu/hr Degrees F or the metric calculations if you prefer. Assume the system is under 15# pressure, 180 degree F Tstat, and all air is purged from the system and an assumed 100 degree F ambient temp.
Hopefully, this will end the erroneous supposition the the coolant must be slow through the radiator.......
just my opinion......
BOB RENTON

 

[Jeff Peterson]

" It is important to understand that the cooling system has different pressures in different areas. Bernoulli’s principle shows us that flow will indicate pressure levels. Areas of high flow, such as the return line from the radiator to the water pump, will have relatively lower pressures. Areas of low flow, such as in front of the thermostat or convoluted areas of the engine block and cylinder head, will have relatively high pressures."

COOLANT FLOW IS KING​

Simply put, the greater the coolant flow, the easier it is to keep your engine cool. There is a stupid myth going around that states you don’t want coolant moving through your engine too quickly. The thought is that coolant needs to stay in the radiator longer to reject more heat and in the engine longer to absorb more heat… all of this is dumb.

You want as high of coolant volume moving as possible. Why? Water absorbs and dissipates heat on an exponential curve. The longer you cool water, the rate at which is cools decreases and the longer you heat water, the rate at which it heats decreases. All this assumes a consistent source of external heating or cooling.

If you slowly flow the water to absorb more heat from the engine, as the water warms, the rate at which it absorbs the heat drops, causing the engine components themselves to heat up. The same goes for the radiator. The more slowly you flow coolant through it, the more the rate of the water cooling slows down. Therefore, if you have higher flow rates, you can keep the water doing its job most efficiently. Additionally, higher flow rates will cause the engine to be more evenly cooled, as the coolant is working in a narrower temperature range.

 

[Cranky]

Not true....please show us all your calculations included flow velocity and temperature differences both in/out of engine AND radiator....for a given RPM to balance the volume calculations...(realizing that pump volume varies with pump rpm) and the specific heat characteristics of the choosen coolant. The greater delta T between the air and coolant, the more heat is exchanged....in Btu/hr Degrees F or the metric calculations if you prefer. Assume the system is under 15# pressure, 180 degree F Tstat, and all air is purged from the system and an assumed 100 degree F ambient temp.
Hopefully, this will end the erroneous supposition the the coolant must be slow through the radiator.......
just my opinion......
BOB RENTON

Uhh....no

 

[josephqatarcarguy]

in my 16 years of building / owning daily driven American muscle cars here in the desert , all the cars ran better / cooler with a thermostat in them , 220 on a 117f weather day on the highway is fair especially since my car has a built up engine , most cars i build to be daily drivers with a wee bit of grunt rins 190- 210 in this weather , also as @RustyRatRod stated on one of pages 220 is not overheating if the temps come down ......

 

[68-500]

in my 16 years of building / owning daily driven American muscle cars here in the desert , all the cars ran better / cooler with a thermostat in them , 220 on a 117f weather day on the highway is fair especially since my car has a built up engine , most cars i build to be daily drivers with a wee bit of grunt rins 190- 210 in this weather , also as @RustyRatRod stated on one of pages 220 is not overheating if the temps come down ......

Seems like you have answered your question.