Thermostats - high flow vs standard flow - now I am confused

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cudajames

cudajames

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In the process of completing a 408 stroker. I am going with FlowKooler 1700 high flow water pump. I will also be using an after market radiator

I've read that a high flow water pump requires a high flow thermostat and I've read that it needs a standard flow to slow down the flow of water. Which sort of doesn't make sense

It is my understanding the difference between the t-stats is amount of water let in when open, which a high flow water pump can maximize the circulation of the water. So if the radiator is working properly cooling the engine.

Am I missing anything?
 
When the thermostat opens it allows the coolant to flow into the top of the rad, down thru the core and then back into the engine block.
If I got this right you are asking about flow. If the flow is too fast it hasn't had time to cool in the rad core so a higher temp will result.
That's why some have a overheat problem when not using a thermostat.Something has to regulate the flow(restrict).
You may try the high flow T-stat first and see if the temps are to you liking.Too hot ? then replace with a standard flow.
Old school guys would drill the T-stat plate out giving more flow or replace with a metal disc with a 5/8'' hole to slow the coolant down as necessary.
 
I run a Flowkooler pump and Milodon high flow 185 stat in my 383 with otherwise all stock cooling components. When the stat opens you want max flow. Don’t confuse why the stat is there. It is used to bring the engine to temp then regulate the flow. Even a high flow stat restricts the flow enough to allow proper cooling through the radiator, all other proper components considered.
 
The hi flows put the aperture out further from the center. So the same amount of vertical pellet movement has a greater cross-sectional flow area.
IMO the non-hi-flows should be called flow chokes, cuz when you look at them full open it makes you wonder who the twerp was that thought of doing that, so you could call him up on the phone, and voice your opinion,lol.
And yeah, the stat sets the minimum water temp.If your system overcools, the stat will begin to close and attempt to maintain the coolant temp at or near it's rating. Once the temp is above the stat rating it is supposed to be wide open and doing nothing.
 
Stant Superstat 180F #45478 (test before install to be safe)
Felpro #35063
 
So what is the proper temp (thermostat) for an iron block with X heads and AC. I see al kinds of info on temps.
Thanks FABO
 
the thermostat keeps the motor warm. if it needs to open all the way to cool the motor, you don't want one that restricts flow
 
blewbyoutobad said:
So what are safe temps 180 to 200 run temp?
Click to expand...
That would depend on the engine and the application, but yeah 180 to 200 should be safe for a streeter.
Generally; I've heard it said that the colder below 180 you run it the faster and the more it will wear. Yet on the dyno they often make best power at cooler temps.
Generally; I've heard it said that engines make better fuel mileage at higher temps, and that might be substantiated by the fact that most modern systems do run much hotter than in the old days.
I've run 207 since 2004. Makes good power, great fuel economy, and the engine has over 100,000 on it and still runs like a scalded dog. Your results may vary.....
 
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If you have a high flow water pump doesn't it make sense to use a high flow thermostat also ? How can a high flow water pump work at its best if it's choked down by a standard thermostat . High flow stats are NOT that expensive . I used a high flow stat with a high flow w.p. and clutch fan and my temp dropped 12*F. Did not completely solve the problem but helped a ton
 
If the cooling system is working correctly, it shouldn't make a difference.
I like the hi-flow because it seems to be a little more accurate and consistent than anything else I have run. So I trust it. And so,I can concentrate on keeping the car between the ditches, and not banging into immovable objects, or falling into holes, lol.
Since I put it in (2002IIRC) I have never had an overheat.
 
Thanks all, have only driven the car twice, 8 miles. Overheated big time on first run, original copper radiator and flex fan, 160 high flow stat and water pump. Switched to a 3 row Champion radiator and lowered to 200. No shroud with a 17" flex fan 1" behind core. During build I installed AC and I think the AC condenser is to small and it does block part of the hole for the radiator. Next run I'm removing it to see what happens.
 
blewbyoutobad said:
Thanks all, have only driven the car twice, 8 miles. Overheated big time on first run, original copper radiator and flex fan, 160 high flow stat and water pump. Switched to a 3 row Champion radiator and lowered to 200. No shroud with a 17" flex fan 1" behind core. During build I installed AC and I think the AC condenser is to small and it does block part of the hole for the radiator. Next run I'm removing it to see what happens.
Click to expand...
So just to decrypt this; Are you still running the 17" flex fan with no shroud ? Is there a fan-clutch?
And at what speed does the overheat occur, and at what rpm?
 
AJ/FormS said:
The hi flows put the aperture out further from the center. So the same amount of vertical pellet movement has a greater cross-sectional flow area.
IMO the non-hi-flows should be called flow chokes, cuz when you look at them full open it makes you wonder who the twerp was that thought of doing that, so you could call him up on the phone, and voice your opinion,lol.
And yeah, the stat sets the minimum water temp.If your system overcools, the stat will begin to close and attempt to maintain the coolant temp at or near it's rating. Once the temp is above the stat rating it is supposed to be wide open and doing nothing.
Click to expand...

I go w/ the above 2 posts -------
 
AJ, Yes still 17" flex with no shroud. Fan is 1" from core. No fan clutch, this is an all new car and the overheats happen just by trying to get some miles for check out. Initially I start around the neighborhood, then the county roads at no more than 60mph. I'm at 200 on the county roads heading back to the house. Last trip was 6 miles and this happened. Freeze plugs started seeping after first run so I pulled them all. Machine shop installed them with no sealant, so I am redoing that right now before next run. This is a 4 speed car with 3:91s.
 
Well, I hate to sound like a broken record, but the flexfan has to go, and you gotta get a shroud.
At speeds above 30/35 ram air is sufficient, or at least doing most of the work, to make the cooling system work. But below that it's all on the fan.
I see two problems;
1) the lack of the shroud allows the fan to pull air around the tips, instead of through the rad and
2)Flex fans, no fan-clutch, 3.91s and a 4 speed is a recipe for disaster. Because the engine rpm is almost instantly up, and the flex fan does what flexfans do, stops pulling. But just as bad is that now, without a clutch, it becomes a road block to air trying to be rammed thru the rad by windspeed. I mean the air coming in only has 1" to turn and try and get around the spinning wall called a flex fan.
By 20 mph your rpm in first gear is up around 2600. By 30 then, it is 3900 so you have probably shifted into second and are cruising at 2800. Pop your hood and watch the fan flatten out as you rev the engine to these rpms.
With the engine idling, put an 8.5x11 sheet of paper in front of the rad. Notice how hard the paper is being sucked onto the rad. Now rev it up to 2600 and again pull the sheet off. Compare the two.

Ok now the solution to your problem is this;
1) a 7-blade all-steel, hi-attack, fan, and
2) a tight-fitting shroud, about 1" at the closest point, closer if you have restrained the engine, and
3) pull the fan away from the rad until the blades are half way out of the shroud. and
4) if you got the cash, I highly recommend a HD Thermostatic fan clutch.
The thermostat sets the minimum water temperature. In the same way, the T-clutch sets the maximum water temp........ so long as the rad is physically able to shed the heat. Once you have the engine operating between the minimum and the maximum, then you can tune the beast.
5) optional but very important, is to get fresh cold air down the carb.As long as it is sucking hot air, the engine will never reach it's full potential.

Here's something to think about, your fan is not just there to pull air thru the rad at speeds below 30/35 mph. In order for air to come into the engine bay, the air that is already there has to first make room for it......... so the fan also has to push it out. And it has to fight the hot air near the headers which is expanding and desperately trying to rise up thru the hood and is usually getting sucked into the carb; None of which is a good idea. That flex fan is killing your engine, get rid of it.
That's my opinion..... and my experience.
 
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cudajames said:
In the process of completing a 408 stroker. I am going with FlowKooler 1700 high flow water pump. I will also be using an after market radiator

I've read that a high flow water pump requires a high flow thermostat and I've read that it needs a standard flow to slow down the flow of water. Which sort of doesn't make sense

It is my understanding the difference between the t-stats is amount of water let in when open, which a high flow water pump can maximize the circulation of the water. So if the radiator is working properly cooling the engine.

Am I missing anything?
Click to expand...
 
cudajames said:
In the process of completing a 408 stroker. I am going with FlowKooler 1700 high flow water pump. I will also be using an after market radiator

I've read that a high flow water pump requires a high flow thermostat and I've read that it needs a standard flow to slow down the flow of water. Which sort of doesn't make sense

It is my understanding the difference between the t-stats is amount of water let in when open, which a high flow water pump can maximize the circulation of the water. So if the radiator is working properly cooling the engine.

Am I missing anything?
Click to expand...

I've always been under the impression Hi Flow water pump, Hi Flow stat. Why not check with FlowKooler, and see what they recommend ? Just a phone call away.
 
The answer is yes, a high flow thermostat should be used with a high flow water pump. An Edelbrock performance water pump puts out 20% more flow than an OEM pump and an equivalent amount of pressure. Do not confuse flow with pressure. Flow and pressure promote better cooling. Cooling is a function of the difference in temperature between the coolant and its heat sink. Picking up heat from the engine follows the same function. Flow is important because it creates eddy currents that mix the hot and cooler coolant in the engine cooling ports and the radiator tubes. Otherwise, the coolant stagnates at the center of the passages and does not mix with the hot coolant. Newer engines have very small passages to facilitate that process.
Take a look at this blog post from my website. UPGRADED PERFORMANCE RACING RADIATORS. Think about standing outside with a wet shirt on at say, 40 degrees. With no wind, you may feel cold but not as much as you do with even a slight breeze. What happened is that you released more heat with the air passing over your body like water would pass over the engine and through the radiator. This post may also be of help Racing and Performance Water Pumps.

Thanks
Jean Genibrel
Appliedspeed.com
 
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I think my Hi-flow, is called a hi-flo for two reasons; #1, it opens WITH the flow instead of against it, and #2, it has a huge opening when it is fully open.
My Milodon was new in about 2001 or 2002. It was deadly consistent, including a fast warm-up, and it is still in the car today.
 
Jean Genibrel said:
Do not confuse flow with pressure. Great flow does not promote better cooling. The coolant needs time to transfer heat to the air and it needs time to pick up heat from the engine. Take a look at this blog post from my website. UPGRADED PERFORMANCE RACING RADIATORS. Think about standing outside with a wet shirt on at say, 40 degreesF. With no wind, you may feel cold but not as much as you do with even a slight breeze. What happened is that you released more heat with the air passing over your body like water would pass over the engine and through the radiator. This post may also be of help Racing and Performance Water Pumps.

Thanks
Jean Genibrel
Appliedspeed.com
Click to expand...


I’ve read through 3 threads on here on Sunday about cooling and I’m pretty sure there are some here who would argue with your theory that the coolant needs to stay in the radiator longer. You can use the search feature and find the threads.
 
AJ/FormS said:
Well, I hate to sound like a broken record, but the flexfan has to go, and you gotta get a shroud.
At speeds above 30/35 ram air is sufficient, or at least doing most of the work, to make the cooling system work. But below that it's all on the fan.
I see two problems;
1) the lack of the shroud allows the fan to pull air around the tips, instead of through the rad and
2)Flex fans, no fan-clutch, 3.91s and a 4 speed is a recipe for disaster. Because the engine rpm is almost instantly up, and the flex fan does what flexfans do, stops pulling. But just as bad is that now, without a clutch, it becomes a road block to air trying to be rammed thru the rad by windspeed. I mean the air coming in only has 1" to turn and try and get around the spinning wall called a flex fan.
By 20 mph your rpm in first gear is up around 2600. By 30 then, it is 3900 so you have probably shifted into second and are cruising at 2800. Pop your hood and watch the fan flatten out as you rev the engine to these rpms.
With the engine idling, put an 8.5x11 sheet of paper in front of the rad. Notice how hard the paper is being sucked onto the rad. Now rev it up to 2600 and again pull the sheet off. Compare the two.

Ok now the solution to your problem is this;
1) a 7-blade all-steel, hi-attack, fan, and
2) a tight-fitting shroud, about 1" at the closest point, closer if you have restrained the engine, and
3) pull the fan away from the rad until the blades are half way out of the shroud. and
4) if you got the cash, I highly recommend a HD Thermostatic fan clutch.
The thermostat sets the minimum water temperature. In the same way, the T-clutch sets the maximum water temp........ so long as the rad is physically able to shed the heat. Once you have the engine operating between the minimum and the maximum, then you can tune the beast.
5) optional but very important, is to get fresh cold air down the carb.As long as it is sucking hot air, the engine will never reach it's full potential.

Here's something to think about, your fan is not just there to pull air thru the rad at speeds below 30/35 mph. In order for air to come into the engine bay, the air that is already there has to first make room for it......... so the fan also has to push it out. And it has to fight the hot air near the headers which is expanding and desperately trying to rise up thru the hood and is usually getting sucked into the carb; None of which is a good idea. That flex fan is killing your engine, get rid of it.
That's my opinion..... and my experience.
Click to expand...
 
cudajames said:
In the process of completing a 408 stroker. I am going with FlowKooler 1700 high flow water pump. I will also be using an after market radiator

I've read that a high flow water pump requires a high flow thermostat and I've read that it needs a standard flow to slow down the flow of water. Which sort of doesn't make sense

It is my understanding the difference between the t-stats is amount of water let in when open, which a high flow water pump can maximize the circulation of the water. So if the radiator is working properly cooling the engine.

Am I missing anything?
Click to expand...
 
You might look into an electric fan.
Also, remember:
Get the hot air out from under the hood with hood scoops
Do not slow the water pump down
Use Redline's Water Wetter and straight water
Install a performance radiator
Install a high pressure/high flow water pump like an Edelbrock
Lower temp thermostat.

Warning: Not all aftermarket radiators are performance radiators. All the auto parts stores sell aftermarket radiators.
 
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