Coolant flow

[Phreakish]

Coolant system pressure is tied to operating temperature limits. If you never want to see 200+, then the cap can be as low as you like. If you expect to see 220-260, then a higher rating is needed.
Boiling temperature vs pressure is shown below. Note that it's pisa (absolute), which means 'zero' pressure is actually 14.7psi. Note that with a 15lbs cap, boiling point is raised to ~250F.
Running 'too high' a pressure cap can damage things like heater cores IF you bleed all the air out and IF you ever actually get to that pressure.
10-16lbs seems to be a reasonable range for most engines, but 4-10 should do well if the cooling system isn't junk.

Mass flow dictates everything when it comes to heat transfer.
Qt = m x Cp x ΔT
m = mass flow, Cp is heat capacity, and delta-T is the temperature differential. Qt is higher if you increase any of those. Since we can't change Cp of anything (assuming away the change in density as a function of temperature), the mass flow and change in temp is the only thing we can vary. If we reduce mass flow, we need to increase the change in temp. Which means if you have a shitty water pump, or under-driven one, then the radiator fan has to work overtime and increase either the flow of air (fan speed), or the change in air temp (number of cores, effectively).
It's stupidly easy to change the fan or water pump speed (lots of pulley sizes available!) so why anyone would advocate to try and change the delta-T is beyond me. A higher flowing thermostat design will also help ensure enough coolant is moving about.

 

[Phreakish]

1. stuart's offers some of the best cooling system info youll ever find, period!
2.stuart's sales top shelf cooling products, period!
3. if you gonna run a a thermostat, run a stuarts fail open stats! i dont see the need for one in most my cars!
4. electric fans ant as good as mechanical fan! why dont dirt track race cars run eletric set ups, cause thay wont keep engine cool, thay run a fixed 4 blade fan! its there go to set up cause its all that will work!!! on a street car i like a good flex fan too!
5. circle track racing is the only place youd ever want to slow down your pump/water flow! 1 to 1 pulley's what most run! on a street car id be looking for over drive pulley's if having heating issues!

The thing with a race car is that the alternator would effectively be converting rpm to electricty to run the fan anyway, so you might as well run it off the engine.
Engine driven fans suck anywhere but higher rpms, which is why most hot rodders overheat in traffic and not on the highway. OEMs have been using electric fans for years without issue, even on high output engines. There's absolutely no case where they can't work unless someone is a cheapskate and can't wire.

 

[dirty white boy]

The thing with a race car is that the alternator would effectively be converting rpm to electricty to run the fan anyway, so you might as well run it off the engine.
Engine driven fans suck anywhere but higher rpms, which is why most hot rodders overheat in traffic and not on the highway. OEMs have been using electric fans for years without issue, even on high output engines. There's absolutely no case where they can't work unless someone is a cheapskate and can't wire.

most dirt cars dont run alternators, and its the only place i know of a good electric fan properly set up and wired wont work! it cause of the sustained high rpms over time! go check out a good super street class or one of the chevy crate engine class's thay all have biggest double pass aluminum radiators that fit, 1 to 1 pulleys and a fixed 4 blade fan! anything less and by end of 30 to 50 laps will be pulling in pits puking coolant!! if thay running that E85 and run up front in clean air then some will cut 2 blades off but every piece of the cooling system will be high dollar CV products and thay still 220 to 240 degrees at end of 30 laps!

​

 

[Phreakish]

most dirt cars dont run alternators, and its the only place i know of a good electric fan properly set up and wired wont work! it cause of the sustained high rpms over time! go check out a good super street class or one of the chevy crate engine class's thay all have biggest double pass aluminum radiators that fit, 1 to 1 pulleys and a fixed 4 blade fan! anything less and by end of 30 to 50 laps will be pulling in pits puking coolant!! if thay running that E85 and run up front in clean air then some will cut 2 blades off but every piece of the cooling system will be high dollar CV products and thay still 220 to 240 degrees at end of 30 laps!

​

The exception proves the rule. There's electric fans which outperform engine driven ones. They just don't make sense on dirt cars - no use in turning HP into electrons back into HP - just bolt the fan to the WP and be done.

There are so many super high output vehicles out there which use only electric fans and are designed for massive sustained horsepower output. To claim electric fans are somehow inferior is simply false. The few places where engine driven fans make sense don't make electric fans irrelevant.

 

[RustyRatRod]

Coolant system pressure is tied to operating temperature limits. If you never want to see 200+, then the cap can be as low as you like. If you expect to see 220-260, then a higher rating is needed.
Boiling temperature vs pressure is shown below. Note that it's pisa (absolute), which means 'zero' pressure is actually 14.7psi. Note that with a 15lbs cap, boiling point is raised to ~250F.
Running 'too high' a pressure cap can damage things like heater cores IF you bleed all the air out and IF you ever actually get to that pressure.
10-16lbs seems to be a reasonable range for most engines, but 4-10 should do well if the cooling system isn't junk.
View attachment 1716086345

Mass flow dictates everything when it comes to heat transfer.
Qt = m x Cp x ΔT
m = mass flow, Cp is heat capacity, and delta-T is the temperature differential. Qt is higher if you increase any of those. Since we can't change Cp of anything (assuming away the change in density as a function of temperature), the mass flow and change in temp is the only thing we can vary. If we reduce mass flow, we need to increase the change in temp. Which means if you have a shitty water pump, or under-driven one, then the radiator fan has to work overtime and increase either the flow of air (fan speed), or the change in air temp (number of cores, effectively).
It's stupidly easy to change the fan or water pump speed (lots of pulley sizes available!) so why anyone would advocate to try and change the delta-T is beyond me. A higher flowing thermostat design will also help ensure enough coolant is moving about.

Well aware of that. But with today's modern ultra efficient radiators, there's just zero need for a high pressure cap.

 

[Phreakish]

Well aware of that. But with today's modern ultra efficient radiators, there's just zero need for a high pressure cap.

Definitely wasn't aimed at you, but the topic. I know you already know pretty much all of that lol.
I think we're saying the same thing. Only reason for a high pressure cap (over ~12lbs) is to crutch a marginal system on an all-iron engine. Between better tuning and better radiators/pumps, the cap is no place to look for system gains - even with an all iron motor.

 

[RustyRatRod]

Definitely wasn't aimed at you, but the topic. I know you already know pretty much all of that lol.
I think we're saying the same thing. Only reason for a high pressure cap (over ~12lbs) is to crutch a marginal system on an all-iron engine. Between better tuning and better radiators/pumps, the cap is no place to look for system gains - even with an all iron motor.

I cannot agree more.

 

[92b]

Well aware of that. But with today's modern ultra efficient radiators, there's just zero need for a high pressure cap.

Like most things it can be application specific. Once the cap lets all the water out it's game over. A higher pressure cap might buy you some laps or a little more time. That might be enough to make the difference between finishing in the money and a DNF. If your application is just cruising to the Dairy Queen then you just pull over and let it cool down.

 

[72bluNblu]

Re-read this part:



I speak from my experience in particular regarding an electric with a flat shroud w/bulky fan blade impeding airflow. Packing up. There’s much about that exact problem on this forum.

The one I had worked great at slower speed, stop and go, but I had to run it continuously always so as not to run past 215° at highway speeds, (it should have been designed better with vents on each corner with flaps) but one time the temp went through the roof when I had an electrical issue and the fan wouldn’t run but luckily I was able to ease it home. Out it came for a mechanical setup as the possible minor gains at the drag strip just wasn’t worth it on the street in my case.

Yes, a well designed shroud and electric fan wouldn’t be a problem. I never implied otherwise. And I never said anything about having to run a mechanical fan for best cooling either.

Not sure what your post is all about.

"Packing up", as you put it, is a rare problem usually only associated with flat plate style shrouds that come on the cheapest of cheap aftermarket electric fans. If a fan's shroud has flaps, that should be a dead giveaway is wasn't actually designed to flow air and that it was just slapped together and band-aided. There are a lot of aftermarket electric fans and shrouds that have no business on cars- their fan CFM ratings are too low, and their shrouds are simply a way to mount their cheap fans, not actually flow air.

I did read what you wrote, and you said "good mechanical fan" was necessary. It's not, a good electric fan and shroud work great. Maybe that's not what you meant, but that is in fact what you said.

2. High flow water pump. I don’t care about the arguments about why the FSM says about how many blades with AC or non AC and all that. You want as many blades as you can get. The exception to that is the Flowkooler pumps because they use a different design. Either way, a quality high flow pump is a must.

You should care, because getting it wrong can mean cavitation in the water pump. The cars that had 1.3:1 and 1.4:1 pulley ratios had pumps with fewer blades. The reason is the RPM of the pump and cavitation, not the amount of water it's pumping. Running a high flow pump is good and the idea you can flow water too fast is silly, I agree. But, you still have to consider the RPM of the pump and how it's being driven. A 1:1 pulley ratio with a high flow water pump is one solution, but if your pulley ratio is 1.4:1 you need to account for that too. Some of the pumps are designed differently now, but the factory was looking at the pumps driven speed and adjusting the blades accordingly.

3. A QUALITY high flow thermostat. IMO the best one (and only choice) is the Stewart Components thermostat. They are fully open by their rated temperature and they are very accurate. At the same time, you should be considering what temperature you want the engine to maintain. Again, my opinion is that any of the engines we discuss here should NEVER get over 180. Thats it. Any more than that and you are pissing away power. How so? You make the engine way more detonation prone. You can’t run as much compression. You end up retarding the timing to help reduce detonation, which can cause higher engine temperatures. If you want to run unorthodox compression ratios on pump gas then the goal should be 160 degrees and no more. You can run 12:1 (and probably a bit more if you are real careful and want to get your tune down to the gnats ***) on pump gas. Premium of course but it’s still pump gas. And that makes power. Everywhere. And driveability.

The majority of your points are right on and I agree, but you leave science behind on this point and just go with what you're personally familiar with.

The 180° temp thing is just left over from your drag racing background. Not every car/engine that gets discussed on this board is used the same way. If 180° was some magic number, the modern OEM cars would use it too. Yes, modern cars have to tune for a lot of other things too, but they all make higher hp/cube outputs than these cars ever did stock- they're more powerful and efficient. Sure, the engines discussed here usually aren't stock and don't have smog to worry about, but most of them also don't have nearly the control over their fuel delivery and ignition systems either. Literally no modern cars spec their water temps to be 180°, and a couple dozen degrees of coolant temperature aren't going to hammer your cylinder and exhaust temps so badly that you couldn't deal with meeting the smog and efficiency requirements. Modern OEM's could easily spec a 180° water temp if it made the most power or was the most efficient. They don't, and it's not because they don't know what they're doing.

If you were familiar with other kinds of racing, you'd know that pretty much only drag racing cars keep their engine temps under 180°. There are much crazier and exotic engine builds out there than make gobs of power for a lot longer than drag engines do and do it with much higher coolant temperatures. For a street car, it's not necessary or often even practical to keep the coolant temps between 160° and 180°.

4. electric fans ant as good as mechanical fan! why dont dirt track race cars run eletric set ups, cause thay wont keep engine cool, thay run a fixed 4 blade fan! its there go to set up cause its all that will work!!! on a street car i like a good flex fan too!

Yeah, that's just BS. Modern cars pretty much ALL run electric fans, and some of them make more horsepower than dirt track cars too. Using a race car as an example is also usually a bad idea, since there are typically specific rules and regulations that require certain things and not others. And pretty much every automotive racing environment is highly specialized, and requires things that don't make sense on a street car. Why dirt track cars run mechanical fans instead of electric I don't know, but it's absolutely not because electric fans aren't capable of cooling those cars.

 

[RustyRatRod]

Like most things it can be application specific. Once the cap lets all the water out it's game over. A higher pressure cap might buy you some laps or a little more time. That might be enough to make the difference between finishing in the money and a DNF. If your application is just cruising to the Dairy Queen then you just pull over and let it cool down.

Have you seen us at the Dairy Queen? LOL That is one of our stops.

And yes, I agree 100% that it's application specific. But I never have to pull over and let it cool down, because it never over heats. Not even close.

 

[RustyRatRod]

"Packing up", as you put it, is a rare problem usually only associated with flat plate style shrouds that come on the cheapest of cheap aftermarket electric fans. If a fan's shroud has flaps, that should be a dead giveaway is wasn't actually designed to flow air and that it was just slapped together and band-aided. There are a lot of aftermarket electric fans and shrouds that have no business on cars- their fan CFM ratings are too low, and their shrouds are simply a way to mount their cheap fans, not actually flow air.

I did read what you wrote, and you said "good mechanical fan" was necessary. It's not, a good electric fan and shroud work great. Maybe that's not what you meant, but that is in fact what you said.



You should care, because getting it wrong can mean cavitation in the water pump. The cars that had 1.3:1 and 1.4:1 pulley ratios had pumps with fewer blades. The reason is the RPM of the pump and cavitation, not the amount of water it's pumping. Running a high flow pump is good and the idea you can flow water too fast is silly, I agree. But, you still have to consider the RPM of the pump and how it's being driven. A 1:1 pulley ratio with a high flow water pump is one solution, but if your pulley ratio is 1.4:1 you need to account for that too. Some of the pumps are designed differently now, but the factory was looking at the pumps driven speed and adjusting the blades accordingly.


The majority of your points are right on and I agree, but you leave science behind on this point and just go with what you're personally familiar with.

The 180° temp thing is just left over from your drag racing background. Not every car/engine that gets discussed on this board is used the same way. If 180° was some magic number, the modern OEM cars would use it too. Yes, modern cars have to tune for a lot of other things too, but they all make higher hp/cube outputs than these cars ever did stock- they're more powerful and efficient. Sure, the engines discussed here usually aren't stock and don't have smog to worry about, but most of them also don't have nearly the control over their fuel delivery and ignition systems either. Literally no modern cars spec their water temps to be 180°, and a couple dozen degrees of coolant temperature aren't going to hammer your cylinder and exhaust temps so badly that you couldn't deal with meeting the smog and efficiency requirements. Modern OEM's could easily spec a 180° water temp if it made the most power or was the most efficient. They don't, and it's not because they don't know what they're doing.

If you were familiar with other kinds of racing, you'd know that pretty much only drag racing cars keep their engine temps under 180°. There are much crazier and exotic engine builds out there than make gobs of power for a lot longer than drag engines do and do it with much higher coolant temperatures. For a street car, it's not necessary or often even practical to keep the coolant temps between 160° and 180°.



Yeah, that's just BS. Modern cars pretty much ALL run electric fans, and some of them make more horsepower than dirt track cars too. Using a race car as an example is also usually a bad idea, since there are typically specific rules and regulations that require certain things and not others. And pretty much every automotive racing environment is highly specialized, and requires things that don't make sense on a street car. Why dirt track cars run mechanical fans instead of electric I don't know, but it's absolutely not because electric fans aren't capable of cooling those cars.

I agree 100%. Modern cars are almost 100% electric fans now. BUT, they aren't cheapass chinsey crap that most guys try to pay as little as possible for. And I don't care how MANY TIMES you or I preach it, you cannot get people stuck on CHEAP **** to listen. You and I both know full well that if an electric fan doesn't flow 3000 or more.....and preferably 4000 it ain't gonna cool very well. You have to get a goodun. I like your idea of the Ford fan I forget which it is......Taurus? Those two speed ones MOVE SOME AIR on high.

 

[12many]

"Packing up", as you put it, is a rare problem usually only associated with flat plate style shrouds that come on the cheapest of cheap aftermarket electric fans. If a fan's shroud has flaps, that should be a dead giveaway is wasn't actually designed to flow air and that it was just slapped together and band-aided. There are a lot of aftermarket electric fans and shrouds that have no business on cars- their fan CFM ratings are too low, and their shrouds are simply a way to mount their cheap fans, not actually flow air.

I did read what you wrote, and you said "good mechanical fan" was necessary. It's not, a good electric fan and shroud work great. Maybe that's not what you meant, but that is in fact what you said.



You should care, because getting it wrong can mean cavitation in the water pump. The cars that had 1.3:1 and 1.4:1 pulley ratios had pumps with fewer blades. The reason is the RPM of the pump and cavitation, not the amount of water it's pumping. Running a high flow pump is good and the idea you can flow water too fast is silly, I agree. But, you still have to consider the RPM of the pump and how it's being driven. A 1:1 pulley ratio with a high flow water pump is one solution, but if your pulley ratio is 1.4:1 you need to account for that too. Some of the pumps are designed differently now, but the factory was looking at the pumps driven speed and adjusting the blades accordingly.


The majority of your points are right on and I agree, but you leave science behind on this point and just go with what you're personally familiar with.

The 180° temp thing is just left over from your drag racing background. Not every car/engine that gets discussed on this board is used the same way. If 180° was some magic number, the modern OEM cars would use it too. Yes, modern cars have to tune for a lot of other things too, but they all make higher hp/cube outputs than these cars ever did stock- they're more powerful and efficient. Sure, the engines discussed here usually aren't stock and don't have smog to worry about, but most of them also don't have nearly the control over their fuel delivery and ignition systems either. Literally no modern cars spec their water temps to be 180°, and a couple dozen degrees of coolant temperature aren't going to hammer your cylinder and exhaust temps so badly that you couldn't deal with meeting the smog and efficiency requirements. Modern OEM's could easily spec a 180° water temp if it made the most power or was the most efficient. They don't, and it's not because they don't know what they're doing.

If you were familiar with other kinds of racing, you'd know that pretty much only drag racing cars keep their engine temps under 180°. There are much crazier and exotic engine builds out there than make gobs of power for a lot longer than drag engines do and do it with much higher coolant temperatures. For a street car, it's not necessary or often even practical to keep the coolant temps between 160° and 180°.



Yeah, that's just BS. Modern cars pretty much ALL run electric fans, and some of them make more horsepower than dirt track cars too. Using a race car as an example is also usually a bad idea, since there are typically specific rules and regulations that require certain things and not others. And pretty much every automotive racing environment is highly specialized, and requires things that don't make sense on a street car. Why dirt track cars run mechanical fans instead of electric I don't know, but it's absolutely not because electric fans aren't capable of cooling those cars.

Don’t be a literalist. Packing up, backing up, obstructing, impeding, blocking, restricting, whatever you wanna call it. I posted what I experienced with this Derale:

It wasn’t cheap $$ that’s for sure. Flat plate shroud with high CFM fan. It didn’t take long for me to discover it had to go. You may have known this from the beginning of time, at the time I bought it I had to find an 18 inch fan with shroud that would fit my situation for dragracing and street use. For that it was fine, although I had to run it more than I care to. It was no good for Highway use in my application. And that style is what I am referring to which is the exact same thing you are referring to.

As to your assertion that I said a mechanical fan was “necessary“ maybe you have misread or perhaps you misinterpreted I don’t know, this is exactly what I stated:

you want as much air flow unimpeded: no flat shroud and/or electric fan that has a bulky blade blocking air flow, a good mechanical fan, (fixed or viscous) as big as you can fit

Re-reading what I typed, it could be you are focusing on the part: “and/or” and perhaps I left out “or” between “blocking airflow, OR a good mechanical......” Was not implying having to use both, no sir. Perhaps I was not as specific and clear as I could have been. Grammatical errors happen.
Instead of seemingly looking to pounce and parse maybe try asking for clarity or simply give the benefit of doubt. No big deal. I know I need to sometimes so, anyway, have a nice evening

 

[George Jets]

I don’t know how old that tech page is. Maybe it’s 10 years old. Who knows.

What I do know is part of one part of one of the tech pages (I’m not going back through to see if what you quoted was part of or not) was discussing FLAT HEAD FORDS an what was done to them and why.

Like most things, what was done to the FHF (for good reason BTW) was wrongly applied to everything that came after it. And that’s exactly how **** like slowing coolant flow down keeps getting repeated.

I know you are looking for some thread to grasp to make slowing coolant flow down the correct thing to do but it is wrong.

My attitude is what it is because this same thing comes up on a regular basis and it gets damn old trying to educate and clean up the same error over and and over and over.

I could post another 20 links from 5 other manufacturers and you would quickly read them, pull out some quotes you think fit your myth and then spend 20 paragraphs defending the myth.

You will never learn because you refuse to accept that you won’t let go of the error.

And every time I see this error I will call it out.

There is a reason why guys are fighting cooling issues. One of them is not getting coolant and air flow correct. And that is get the coolant flowing as fast as you can (within reason…you have to keep the belt on and not have the mechanical fan explode if you use one) and do the same with air flow.

So…if someone wants to sit down and PLAN their cooling system (thats what should be done) this is what I would tell them to do.

1. Get the biggest 2 core radiator that will fit. It needs to be aluminum. Why? Because copper/brass may reject heat better than aluminum but what it can’t do is be made to is be made into shapes like 2 large (1 inch or bigger) cores and have enough strength. While you give up a BIT of thermal efficiency with aluminum, you gain that back and then some with it.

2. High flow water pump. I don’t care about the arguments about why the FSM says about how many blades with AC or non AC and all that. You want as many blades as you can get. The exception to that is the Flowkooler pumps because they use a different design. Either way, a quality high flow pump is a must.

3. A QUALITY high flow thermostat. IMO the best one (and only choice) is the Stewart Components thermostat. They are fully open by their rated temperature and they are very accurate. At the same time, you should be considering what temperature you want the engine to maintain. Again, my opinion is that any of the engines we discuss here should NEVER get over 180. Thats it. Any more than that and you are pissing away power. How so? You make the engine way more detonation prone. You can’t run as much compression. You end up retarding the timing to help reduce detonation, which can cause higher engine temperatures. If you want to run unorthodox compression ratios on pump gas then the goal should be 160 degrees and no more. You can run 12:1 (and probably a bit more if you are real careful and want to get your tune down to the gnats ***) on pump gas. Premium of course but it’s still pump gas. And that makes power. Everywhere. And driveability.

4. Fan selection. This is critical. I run a mechanical fan. I may try an electric fan down the road. If you are going to do an electric fan, make sure it’s a QUALITY fan, not some cheap assed junker. I hear the Ford Contour fans are what you’d want and that’s what I’ll try if and when I do it. For a mechanical fan, I use a stainless steel flex fan. I do not use any other. I have done testing in the past and what you save in HP from a thermostatic fan over a fixed fan you lose in temperature control. You need to move some air and I don’t like having the fan engage and disengage based on the temperature some engineer thought was best for a run of the mill engine.

5. To that end, you need to do whatever it takes to at least (at the VERY least) to find pulleys that are 1:1. The water pump should turn no slower than crank speed. Ever. Unless you are shifting at 8k plus RPM and you are worried about the fan exploding (you should be with an overdriven pump). Other than that, get the pump (and the fan if you have a mechanical one) as fast as practicable. I’m at 6% over and I’d love to double that.

If more people were educated in this area to the facts and science of it some of the companies that manufacture pulleys would make them. When I first started calling around to find pulleys every company said the same thing. We get one call for overdriven pulleys for every 200 calls we take for UNDERdriven pulleys. When guys still have bad thinking on this, why would anyone invest in pulleys to speed up the water pump?

The last thing is coolant. I know all the long hairs out there will say water is the best conductor of heat as a coolant medium. And it is. But the issue is my engines are expensive. And water (especially when it it heated and cooled hundreds and thousands of times during its life cycle) is corrosive to the block and heads.

Plus, I drive my junk year around so I need some protection from freezing. I have driven my car on days where the high temperature was in the high teens. Straight water will not allow that.

So you should be running something for winter and corrosion protection.

I am using Evans for several reasons (I’m not sponsored by them, I don’t get product for free and I’m not married to the owners daughter…all of which I’ve been accused of) and two of them are freezing and corrosion protection.

But a HUGE bonus is Evans coolant does not require system pressure to increase the boiling point of the coolant. You have have 220 degree coolant temperature and you can take the cap off while the engine is running and you won’t get burned half to death from hot coolant exploding out of the radiator. That right there should make you consider the product. From a pure safety standpoint.

There is also another bonus from running near zero system pressure and that is with near zero pressure (you may get 1, maybe 2 PSI but probably not) is the fact that it’s easier on the coolant lines, core plugs and even the head gaskets.

With near zero system pressure the load on those parts is significantly reduced. Running 14, 16 or 20 PSI as some guys do is harder on the hoses, core plugs and head gaskets.

If you follow these simple guidelines, you can drive your car right through downtown hell on the hottest day of the year and not have an issue.

Thanks Rat, explained that well.

Lots of people on here have over heating issues, and they never get to the bottom of it.

Thanks

And Yes agree run anti-freeze. It's a sorry sight dumping the coolant on a water run system. Talk about Corrosion and Rust ....

☆☆☆☆☆

 

[Phreakish]

Don’t be a literalist. Packing up, backing up, obstructing, impeding, blocking, restricting, whatever you wanna call it. I posted what I experienced with this Derale:

View attachment 1716086405It wasn’t cheap. Flat plate shroud with high CFM fan. It didn’t take long for me to discover it had to go. You may have known this from the beginning of time, at the time I bought it I had to find an 18 inch fan with shroud that would fit my situation for dragracing and street use. For that it was fine, although I had to run it more than I care to. It was no good for Highway use in my application. And that style is what I am referring to which is the exact same thing you are referring to.

As to your assertion that I said a mechanical fan was “necessary“ I’m sorry you have misread or perhaps you misinterpreted I don’t know, this is exactly what I stated:


Re-reading what I typed, it could beyou are getting hung up on the part: “and/or” and perhaps I left out “or” between “blocking airflow, OR a good mechanical......” Was not implying having to use both, no sir. Perhaps I was not as specific for your liking. Whatever.

Instead of looking to pounce maybe try Asking for clarity or simply give the benefit of doubt. I know I need to sometimes so anyway have a nice evening

That's a cheap junk fan. It's too small, and the shroud is there to increase profit margin. Poor shape and the fan opening is too small relative the radiator area.

A dual fan Ford contour setup is 3400-4000+ cfm on full tilt at 12v. That's for an 4 cylinder with AC and is OEM designed with a good bypass ratio. That derale setup is 1800-2400cfm. It would be marginal in almost every case for a hopped up V8. Add the restrictive and poorly shaped shroud and it's about like blanking the radiator with a sheet of plywood.

 

[92b]

"Packing up", as you put it, is a rare problem usually only associated with flat plate style shrouds that come on the cheapest of cheap aftermarket electric fans. If a fan's shroud has flaps, that should be a dead giveaway is wasn't actually designed to flow air and that it was just slapped together and band-aided. There are a lot of aftermarket electric fans and shrouds that have no business on cars- their fan CFM ratings are too low, and their shrouds are simply a way to mount their cheap fans, not actually flow air.

I did read what you wrote, and you said "good mechanical fan" was necessary. It's not, a good electric fan and shroud work great. Maybe that's not what you meant, but that is in fact what you said.



You should care, because getting it wrong can mean cavitation in the water pump. The cars that had 1.3:1 and 1.4:1 pulley ratios had pumps with fewer blades. The reason is the RPM of the pump and cavitation, not the amount of water it's pumping. Running a high flow pump is good and the idea you can flow water too fast is silly, I agree. But, you still have to consider the RPM of the pump and how it's being driven. A 1:1 pulley ratio with a high flow water pump is one solution, but if your pulley ratio is 1.4:1 you need to account for that too. Some of the pumps are designed differently now, but the factory was looking at the pumps driven speed and adjusting the blades accordingly.


The majority of your points are right on and I agree, but you leave science behind on this point and just go with what you're personally familiar with.

The 180° temp thing is just left over from your drag racing background. Not every car/engine that gets discussed on this board is used the same way. If 180° was some magic number, the modern OEM cars would use it too. Yes, modern cars have to tune for a lot of other things too, but they all make higher hp/cube outputs than these cars ever did stock- they're more powerful and efficient. Sure, the engines discussed here usually aren't stock and don't have smog to worry about, but most of them also don't have nearly the control over their fuel delivery and ignition systems either. Literally no modern cars spec their water temps to be 180°, and a couple dozen degrees of coolant temperature aren't going to hammer your cylinder and exhaust temps so badly that you couldn't deal with meeting the smog and efficiency requirements. Modern OEM's could easily spec a 180° water temp if it made the most power or was the most efficient. They don't, and it's not because they don't know what they're doing.

If you were familiar with other kinds of racing, you'd know that pretty much only drag racing cars keep their engine temps under 180°. There are much crazier and exotic engine builds out there than make gobs of power for a lot longer than drag engines do and do it with much higher coolant temperatures. For a street car, it's not necessary or often even practical to keep the coolant temps between 160° and 180°.



Yeah, that's just BS. Modern cars pretty much ALL run electric fans, and some of them make more horsepower than dirt track cars too. Using a race car as an example is also usually a bad idea, since there are typically specific rules and regulations that require certain things and not others. And pretty much every automotive racing environment is highly specialized, and requires things that don't make sense on a street car. Why dirt track cars run mechanical fans instead of electric I don't know, but it's absolutely not because electric fans aren't capable of cooling those cars.

I said this in another post but the application can be what determines what fan does the best job.

The horsepower rating of the engine is not necessarily a good yardstick for what fan is needed. For example: You have an engine that makes 700 hp and you use that power for an occasional burst of acceleration then spend the rest of the time using 20 hp to cruise down the road or idling at a stop sign. Compare that to an engine that makes 400 horsepower that is being raced in a circle or on a road course that spends most of it's time making close to that 400 horsepower. The cooling needs of the two examples can be very different.

I think a better way to think of how much heat you need to extract is horsepower over time.

Electric fans have come a long way. They are more efficient than ever. But they move the same air if the motor is idling or at full load high rpm. Mechanical fans while not load sensitive are rpm sensitive. They move more air with increased rpm. They also have a power source that can power a large aggressive pitched fan blade. Try putting your hand in front of a radiator with an aggressive fan spinning 6000 rpm inside a good shroud. It moves alot of air.

Something to think about and I don't know the answer too. An aggressive pitched 4 blade mechanical fan can use 7 Hp. Assuming the fan efficiency was close to equal (maybe it isn't) how big would the motor on an electric fan need to be to move the same cfm that the mechanical fan is moving at 6000 rpm?

 

[12many]

That's a cheap junk fan. It's too small, and the shroud is there to increase profit margin. Poor shape and the fan opening is too small relative the radiator area.

A dual fan Ford contour setup is 3400-4000+ cfm on full tilt at 12v. That's for an 4 cylinder with AC and is OEM designed with a good bypass ratio. That derale setup is 1800-2400cfm. It would be marginal in almost every case for a hopped up V8. Add the restrictive and poorly shaped shroud and it's about like blanking the radiator with a sheet of plywood.

No ****. LOL. Not sure you realize what vehicle I have? An A100. Engine under a dog house. 18x18 FSR radiator is all I could find that fit in the tight confines.
And that fan was all I could find to fit the rad. It was a 2-speed, had it wired on high. I can’t recall the exact cfm. Beating a dead horse. Fan Long gone in the rear view. I’m good now.

 

[RustyRatRod]

If you want a REAL electric fan from the aftermarket, look at the Black Magic series fans from Flex A Lite. The ones in the upper CFM ranges AIN'T cheap, but they flat out move some air.

 

[Phreakish]

No ****. LOL. Not sure you realize what vehicle I have? An A100.

So you were screwed right out of the gate, LOL.

 

[12many]

So you were screwed right out of the gate, LOL.

All custom or adapt, improvise. A lot of trial and error.

 

[RustyRatRod]

No ****. LOL. Not sure you realize what vehicle I have? An A100. Engine under a dog house. 18x18 FSR radiator is all I could find that fit in the tight confines.
And that fan was all I could find to fit the rad. It was a 2-speed, had it wired on high. I can’t recall the exact cfm. Beating a dead horse. Fan Long gone in the rear view. I’m good now.

Yeah a fast A100. Has it seen 10s yet?

 

[12many]

If you want a REAL electric fan from the aftermarket, look at the Black Magic series fans from Flex A Lite. The ones in the upper CFM ranges AIN'T cheap, but they flat out move some air.

That’s good info for those in the market.
I ended up using the short Hayden clutch, a modified 18” lovingly and carefully reduced to a 17” (biggest diameter I can fit) MP 5-blade with my CVF pulleys (no under driven nonsense) with an Edelbrock Victor water pump knock-off. The name escapes me. No cooling issues at all. Happy camper.

Yeah a fast A100. Has it seen 10s yet?

On hold @ 11.44’s. Working on a few things to get after it later this year. Push it till a track tells me I need more safety items

 

[RustyRatRod]

That’s good info for those in the market.
I ended up using the short Hayden clutch, a modified MP 5-blade with my CVF pulleys (no under driven nonsense) with an Edelbrock Victor water pump knock-off. The name escapes me. No cooling issues at all. Happy camper.

On hold @ 11.44’s. Working on a few things to get after it later this year. Push it till a track tells me I need more safety items

LOL Those are good problems to have.

 

[Bewy]

False information [ post # 21 ] is still being given about t'stats, this time the Stewart Components Hi flow stats [ same as the Milodon & Mr.Gasket ].

The temp stamped on the stat is the opening temp, not the fully open temp as claimed in post #21. Fully open is another 20-30*. A 180 stat is not fully open until 200-210* & it an industry standard for t'stats. I have tested many of these over the years, using a digital thermometer.

 

[dirty white boy]

"Packing up", as you put it, is a rare problem usually only associated with flat plate style shrouds that come on the cheapest of cheap aftermarket electric fans. If a fan's shroud has flaps, that should be a dead giveaway is wasn't actually designed to flow air and that it was just slapped together and band-aided. There are a lot of aftermarket electric fans and shrouds that have no business on cars- their fan CFM ratings are too low, and their shrouds are simply a way to mount their cheap fans, not actually flow air.

I did read what you wrote, and you said "good mechanical fan" was necessary. It's not, a good electric fan and shroud work great. Maybe that's not what you meant, but that is in fact what you said.



You should care, because getting it wrong can mean cavitation in the water pump. The cars that had 1.3:1 and 1.4:1 pulley ratios had pumps with fewer blades. The reason is the RPM of the pump and cavitation, not the amount of water it's pumping. Running a high flow pump is good and the idea you can flow water too fast is silly, I agree. But, you still have to consider the RPM of the pump and how it's being driven. A 1:1 pulley ratio with a high flow water pump is one solution, but if your pulley ratio is 1.4:1 you need to account for that too. Some of the pumps are designed differently now, but the factory was looking at the pumps driven speed and adjusting the blades accordingly.


The majority of your points are right on and I agree, but you leave science behind on this point and just go with what you're personally familiar with.

The 180° temp thing is just left over from your drag racing background. Not every car/engine that gets discussed on this board is used the same way. If 180° was some magic number, the modern OEM cars would use it too. Yes, modern cars have to tune for a lot of other things too, but they all make higher hp/cube outputs than these cars ever did stock- they're more powerful and efficient. Sure, the engines discussed here usually aren't stock and don't have smog to worry about, but most of them also don't have nearly the control over their fuel delivery and ignition systems either. Literally no modern cars spec their water temps to be 180°, and a couple dozen degrees of coolant temperature aren't going to hammer your cylinder and exhaust temps so badly that you couldn't deal with meeting the smog and efficiency requirements. Modern OEM's could easily spec a 180° water temp if it made the most power or was the most efficient. They don't, and it's not because they don't know what they're doing.

If you were familiar with other kinds of racing, you'd know that pretty much only drag racing cars keep their engine temps under 180°. There are much crazier and exotic engine builds out there than make gobs of power for a lot longer than drag engines do and do it with much higher coolant temperatures. For a street car, it's not necessary or often even practical to keep the coolant temps between 160° and 180°.



Yeah, that's just BS. Modern cars pretty much ALL run electric fans, and some of them make more horsepower than dirt track cars too. Using a race car as an example is also usually a bad idea, since there are typically specific rules and regulations that require certain things and not others. And pretty much every automotive racing environment is highly specialized, and requires things that don't make sense on a street car. Why dirt track cars run mechanical fans instead of electric I don't know, but it's absolutely not because electric fans aren't capable of cooling those cars.

wrong!! go do some research on cooling a dirt track car and you'll learn a thing or two!! go to a dirt track and walk around pits and ask some car owners if you doubt me!! electric fans been tried from high dollar aftermarket to ford 2 speed tarus/mini van fans and no body has yet to get them to work good nuff to run less the ambient temps are 65 degrees or cooler!! dirt racers would love to get red of there mechanical fans cause at race speeds that 30 hp thay could use else wheres, specially in the crate class's where each car got same exact 400 hp engine, thay'd pimp there mom out for a 20 hp advantage!! you can bet on that by god!! brought up cooling a dirt track car cause it takes a good system to get the job done! enjoy reading most of your post as thay are on point with good info, but im right on this, been there and done it, know it, spent good money to learn it!! got 4 crate model's setting here now!

 

[RLF Cuda]

One other consideration is altitude. I live at 5800 feet and air density is 20-25% lower than at sea level. Thiis reduces the mass of air that flows through the radiator for any given CFM rating meaing that you need 25% more air flow to get the same heat removed. Luckily engines make less power at althtude for the same air density issue, but cooling is still a concern. But I do wish I had that HP back that i lost due to altitude. My compensation is that I have mountains to look at and great roads to drive on!