Engine Cooling System Efficiency 5.7 Hemi

[Gr8bawana]

Re examination of the engine cooling system of the 5.7 Hemi

I’m in the process of replacing the stock radiator.

I’m examining the coolant flow and thermostat location on top of the water pump.

Radiator thermostats are not the most technologically advanced devices and routinely overlooked in maintenance schedules.

The first point I want this discussion to open with is the location of the thermostat on top of the water pump,
why is this considered a optimum location is it just for convenience because they are both generally changed in the same interval where as I believe changing or at least inspection of the thermostat should happen sooner perhaps a 2 to 1 ratio or better.

The other discussion within this thread and the different ideologies of engineering and physics is whether top down coolant flow is better than bottom up flow I’ll refrain from bringing up the point of Left VS Right flow of radiator cores

Many members and in general most vehicle owners prefer to use a lower temperature rated coolant temperature thermostat for example I believe 180 F (82 C) is the most popular.

(I’m waiting on parts as of this date and have lots of questions going into my parts cannon)

What is your personal philosophy regarding this subject?

 

[Mister Luck]

 

[Mister Luck]

 

[Mister Luck]

 

[Mister Luck]

 

[Wild one]

It definitely been worst since the pandemic, I for one am hopeful you mousekateers get a chance to go outside and put your bottles away and dryout.

Although I’m kind if going to miss all this affection

For one thing,we all know,you're not going to do squat,lol.As far as i can tell,you just like to beat your own horn,but actually do something,not gonna happen. You want to take pressure off the cooling system,stick a colder thermostat in the truck,the hotter a closed system runs,the more pressure it develops,anybody with an eye and asss?hole knows that,lol. Nobody was picking on you,but you sure seemed to come unglued over nothing,put the pipe away and take a valiumm,.

 

[Mister Luck]

 

[crazykid1994]

The radiator is designed around the truck running loaded to prevent overheating. I’m actually debating on switching back to the mechanical fan over the v6 fan for ac cooling reasons. The stock 203° Thermostat in the hemi is for fuel efficiency as well as hotter temps help piston ring seal and exhaust emissions reduction. The active grill shutters pull temps up to 210 and higher to compound the efficiency of the emissions system. Lowering to a 190 actually reduces the efficiency of the emissions system. And going to a 180 is even worse. I run a 190 as an in the middle since it’s still hotter. The stock radiator is actually quite large and I’ve emailed Mishimoto about a thicker drop in but they said the stock radiator is already decent and they didn’t see a need to design a better one. Coming from a company who literally would sell you anything just to make money. There are a few aftermarket double row all aluminum radiators for our trucks but one company so far that I’ve seen tested has questionable quality control. Your best bet at increasing cooling capability would be a larger fan but as the stock setup is dual fan your only option would be a custom fan setup. I tried installing the newer style pentastar fan with semi good results on getting it running but gave up from the loss of money and headache that I incurred. I wish I had more help with it because the newer pentastar fan would be a sure winner if it was a straight plug in. The v6 fan is great and the fan controller setup I’m using works great as a work around to running a custom tune for the fan and gives me full control of the cooling capacity but I’m more tired of the fan running full blast when the ac is on. I’d rather have the ac fan and the engine fan separate again.

 

[HEMIMANN]

I've always been annoyed by thermostatic mechanical fans, with their always-on architecture. Especially when fluid (usually silicone) leaks and the fans start becoming more and more on in cold weather. Apparently they're cheaper than staged electrics, at least they were. I'd think all the staged electric fan assemblies in production now would have made the price point standard architecture?

 

[Marmay]

(I have no idea what this means)
Is this an attempt at a Shakespearian metaphor?

You got it

 

[Tony1945]

What does your 99 CS Coupe use?

its one of those things in forums where someone trying to imply by lowering operating temperatures (sometime artificially) that more hp can be gained and everyone starts buying into it just because where in actual track use it can be beneficial but daily drivers and fuel economy it is not, but thats not what this thread is about

180 is old school

 

[HEMIMANN]

A full semester of Heat Transfer after 2 full semesters of Thermodynamics, and this is just the basics of the subject.

 

[HEMIMANN]

Re examination of the engine cooling system of the 5.7 Hemi

I’m in the process of replacing the stock radiator.

I’m examining the coolant flow and thermostat location on top of the water pump.

Radiator thermostats are not the most technologically advanced devices and routinely overlooked in maintenance schedules.

The first point I want this discussion to open with is the location of the thermostat on top of the water pump,
why is this considered a optimum location is it just for convenience because they are both generally changed in the same interval where as I believe changing or at least inspection of the thermostat should happen sooner perhaps a 2 to 1 ratio or better.

The other discussion within this thread and the different ideologies of engineering and physics is whether top down coolant flow is better than bottom up flow I’ll refrain from bringing up the point of Left VS Right flow of radiator cores

Many members and in general most vehicle owners prefer to use a lower temperature rated coolant temperature thermostat for example I believe 180 F (82 C) is the most popular.

(I’m waiting on parts as of this date and have lots of questions going into my parts cannon)

What is your personal philosophy regarding this subject?

Here you go, OP - only 812 pages to go, excepting the radiation section.

 

[Rod H]

I use a 180 thermostat because of towing and being in the mountains.

 

[pacofortacos]

It's opposite of that.Suction side is bottom of engine aka lower rad hose,top side is pressure or pump side.That's why the bottom hose has a spring inside it to keep it from collasping under suction.They're also a reverse flow cooling system,same as pretty well all modern engines

But don't you think it is easier for the pump to suck from the bottom vs. the top? Wouldn't (shouldn't) be any air at the bottom.
Most impeller pumps are gravity fed that I run into, since when it starts to pump if any air is present, they just cavitate - of course most of the ones I see are 480 Volt and spin to max revs in no time flat.

 

[pacofortacos]

The only reason its designed for 200ish is for Emissions, has zero to do with efficiency. Same reason the put that POS MDS system in. You got to keep those tree hugging snowflakes happy.

I find it helps my mpg also, but that could be the way I use my truck - very little in town, short trip, etc.

 

[pacofortacos]

Just throwing this into the mix, the 4.7's use a 195 thermostat

But does 8 degrees really matter that much. I wonder if they would have gone up a few degrees if it would have helped the 4.7 sludging issue??

 

[pacofortacos]

For one thing,we all know,you're not going to do squat,lol.As far as i can tell,you just like to beat your own horn,but actually do something,not gonna happen. You want to take pressure off the cooling system,stick a colder thermostat in the truck,the hotter a closed system runs,the more pressure it develops,anybody with an eye and asss?hole knows that,lol. Nobody was picking on you,but you sure seemed to come unglued over nothing,put the pipe away and take a valiumm,.

Yeah bad things happen if you run hotter and don't increase pressure.

 

[pacofortacos]

The radiator is designed around the truck running loaded to prevent overheating. I’m actually debating on switching back to the mechanical fan over the v6 fan for ac cooling reasons. The stock 203° Thermostat in the hemi is for fuel efficiency as well as hotter temps help piston ring seal and exhaust emissions reduction. The active grill shutters pull temps up to 210 and higher to compound the efficiency of the emissions system. Lowering to a 190 actually reduces the efficiency of the emissions system. And going to a 180 is even worse. I run a 190 as an in the middle since it’s still hotter. The stock radiator is actually quite large and I’ve emailed Mishimoto about a thicker drop in but they said the stock radiator is already decent and they didn’t see a need to design a better one. Coming from a company who literally would sell you anything just to make money. There are a few aftermarket double row all aluminum radiators for our trucks but one company so far that I’ve seen tested has questionable quality control. Your best bet at increasing cooling capability would be a larger fan but as the stock setup is dual fan your only option would be a custom fan setup. I tried installing the newer style pentastar fan with semi good results on getting it running but gave up from the loss of money and headache that I incurred. I wish I had more help with it because the newer pentastar fan would be a sure winner if it was a straight plug in. The v6 fan is great and the fan controller setup I’m using works great as a work around to running a custom tune for the fan and gives me full control of the cooling capacity but I’m more tired of the fan running full blast when the ac is on. I’d rather have the ac fan and the engine fan separate again.

With both stock fans, I found just removing a few of the upper shutters has kept my temps usually 206 or lower and very steady, even when towing in the summer. Granted I am not towing a huge TT but that boat back there isn't going behind me on it's own. lol

 

[HEMIMANN]

In general, the lower the pump, the more efficient the performance, because the pump has the gravity head of the fluid above to prevent suction cavitation.
Which is why they also took diaphragm fuel pumps off of engine blocks and put in bottom of gas tanks - walla! No more vapor lock, for those of you old enough to remember it.