electric fans?
08-20-2016, 04:38 PM
#1
Instructor
Thread Starter
electric fans?
thinking of putting electric fans on my 73 with ac. i found a company call american volt they sell all kinds of fans and controls. how do i know if the fans will coll the car. the kit i looked at was a 12 inch duel fan curved blades each fan was 80 watts 1400 cfm. what do u think? thanks
The following users liked this post:
The13Bats (08-20-2016)
08-20-2016, 05:01 PM
#3
Team Owner
I have Dual Spals controlled by the FI system via a relay on top of the fans, fed directly off the alt, by a heavy wire up and over....all on or nothing...simple......
I have a '89 F body rad in my car, aluminum/plastic tanks and single row about 1.5" thick......in Florida, it works fine.....
08-21-2016, 02:02 AM
#4
Race Director
Member Since: Mar 2003
Location: Eustis ( Area 51 Bat Cave ) Fl
Posts: 11,608
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thinking of putting electric fans on my 73 with ac. i found a company call american volt they sell all kinds of fans and controls. how do i know if the fans will coll the car. the kit i looked at was a 12 inch duel fan curved blades each fan was 80 watts 1400 cfm. what do u think? thanks
The posts on electric fans seem to get as "heated" as the Radiator posts.
I have been working on my little write ups to try to help I am no guru on the subjects but do research things I post about it and try to keep in what is on this forum the most.
Please see if this helps any, work in progress...
The purpose of the fan be it electric or engine driven is to cool in this case the corvette at idle and at low speeds, if the cooling system is up to par and all the seals and so forth in place the stock engine driven fan has proven to work very well for many decades.
So why swap to an electric fan?
Reasons can range from cooling problems which in that case just adding an electric fan would be a band-aid not a solution and likely not help to people who like to update and upgrade,
Some electric fan companies say you can get an increase of both HP and MPG but in a Corvette that will likely be rather nominal
If you are considering electric fans also consider you will need to upgrade your charging system, while I personally like more it would seem that an over 100 amp Alternator is the least one should consider, in that a larger gauge charging wire is also needed.
There are some people who like a single fan others like dual fans and some people even run 3 fans, lots of ways to get the desired results.
Electric fans, there are a lot to chose from and the pot keeps getting bigger,
Some people like to use fans from other cars like the two speed Taurus fan or mark IV but these are not without the drawbacks of some fabrication to get them to mount to the 68-82 radiator, they do move a lot of air and people who use then are happy.
Some have flat blades which are said to move more air than the curved blades which do not make as much noise.
If money is no object then a look at the new brush less designs might be in order, they do work very well and far more efficient than older motor designs.
Very popular is the dual 11" Spals and they are proven to cool some high HP engine in hot conditions, even though Spal recommends them for "small V8's" and their shroud fails to cover the full 68-82 Corvette radiator core, however they do fit the cramped 68-82 engine compartment very well.
In that popularity ebay is full of cheap import knock offs of the dual Spals, some work good some are just garbage, so if I was to consider the dual 11" Spals I would be sure to get the real name brand or a knock off I new was up to par.
The Dual 11" Spals move about 2780 CFM of air according to spal which is on the low side according to most electric fan manufactures for a car like a Corvette which they recommend at least 3500 CFM.
So how do Dual 11" spals cool so many high demand applications so well?
In all the cases I know of the dual 11" Spals are being adding to aftermarket Aluminum radiators which are actually larger than needed to cool most of the 68-82 Corvette they are on, since the radiator can cool more they get by with a little less air flow from the Spals.
There are other dual fans that move more CFM of air and cover more of the radiator core than the dual 11" Spals such as models from Derale fans, prices seem competitive with the Spals.
Shroud designs,
Even the stock engine driven fan will do very little if the shroud isn't up to par with seals in place and fan spaced correctly,
Electric fan shroud designs vary, but even the single fans have a shroud built around them, dual fans like the Derale or Spals have a duplex shroud, some are open where the blades are and some are divided keeping each side separated.
The simple fact is the fan is only really moving air where is sits on the radiator, for example if I have a radiator 26" x 17" radiator core and a single round 10" electric fan in the center the only air it's pulling is in the 10" circle, easy to see why the more radiator core covered the better as far as efficiency goes, if for example I have dual fans in a duplex shroud and it covers 24" x 12" some radiator core is wasted to a degree, I have seen some clever fabricators extend the shroud to fully cover the radiator.
I have also been told and seen that full coverage isn't needed in the case of the larger aftermarket radiators. ( I am too OCD to waste expensive radiator )
Most larger duplex shrouds have trap doors in them to allow air at speeds to better flow through.
Controllers,
The sky is almost the limit, the factory many times would have the switch temp so high by the time the fans came on the vehicle was already creeping up higher than many people desire, in general one desires the fans to come on just after the thermostat opens for example if you have a 180 thermostat then you want your fan switch to trigger at 190 or a little higher, since the heated coolant is now circulating we need flow to cool it. then if two speeds, 200-210 is about right for high, why let things creep up near overheated temperatures if we do not have to.
Much of this is dictated by the climate of the area, the car is and builders desires...there is no blanket right answer here.
Some people like the high end computer fan controllers, some have fan controls on things like FI and others use lower end temp switches and relay set ups in all cases the fans power leads need to be fused and run through a relay.
Some Taurus fans are single fan dual speeds, the wiring requires relays or a controller that when high is triggered the low power wire doesn't see power.
In the case of dual fans there are many ways to wire it and no one way is 100% right for each person, a builder must decide which is right for them.
One way is both fans come on when the trigger temp is reached, straight up and simple.
a grounding temperature switch is in the engine head, block, intake etc, and when it reaches temperature it send a ground signal to the relay to turn on the fan.
Another way is one fan comes on for low then both fans on for high,
This doesn't work as well on duplex shrouds without the divider because a fan will try to pull from least resistant and that will be the hole of the non running fan, and even with a divided shroud with only one fan on it's basically only pulling from the area it covers.
On the flip side many people use generic single fans fitting two or I have seen 3 on the radiator and run one for low both for high and it works fine again due to the area of radiator it is pulling through is enough to keep things cool.
What GM uses on lot of modern cars is both fans on at low speed wired is series both fans are getting 1/2 power, then when high temp is triggered they switch to parallel wiring and both are getting full power.
Again, all power leads need to be fused and fan supply need relays.
In addition some builders like override switches to turn fans on and off at any time they desire and some like the fans to come on with AC compressor, in most cases that keeps the fans on at higher speeds when not needed a solution to this is wiring the AC override to an AC trinary switch and then it only switches on when needed.
Some people wire to allow the fans to run after the car is shut off with the idea it helps cool the engine compartment, ever seen the warning decals on late models that say "fan may start at any time" this type wiring is what that is from.
I would consider a very important part of adding electric fans is choosing ones with a high CFM rating, if adding to a stock radiator this rating is going to need to be higher than if added to an oversized aftermarket aluminum radiator.
( Please note some fans manufactures measure CFM with no "load" or radiator in front of it, so when the imports brag their 10" fan moves 3000 CFM this is why. )
Another thing to think about is the "zip tie" mounting to the radiator core, this is a quick easy way to mount electric fans and some people get away with it,
I believe it is just asking for core leaks.
Hopefully I shined a little light and made some food for thought.
So why swap to an electric fan?
Reasons can range from cooling problems which in that case just adding an electric fan would be a band-aid not a solution and likely not help to people who like to update and upgrade,
Some electric fan companies say you can get an increase of both HP and MPG but in a Corvette that will likely be rather nominal
If you are considering electric fans also consider you will need to upgrade your charging system, while I personally like more it would seem that an over 100 amp Alternator is the least one should consider, in that a larger gauge charging wire is also needed.
There are some people who like a single fan others like dual fans and some people even run 3 fans, lots of ways to get the desired results.
Electric fans, there are a lot to chose from and the pot keeps getting bigger,
Some people like to use fans from other cars like the two speed Taurus fan or mark IV but these are not without the drawbacks of some fabrication to get them to mount to the 68-82 radiator, they do move a lot of air and people who use then are happy.
Some have flat blades which are said to move more air than the curved blades which do not make as much noise.
If money is no object then a look at the new brush less designs might be in order, they do work very well and far more efficient than older motor designs.
Very popular is the dual 11" Spals and they are proven to cool some high HP engine in hot conditions, even though Spal recommends them for "small V8's" and their shroud fails to cover the full 68-82 Corvette radiator core, however they do fit the cramped 68-82 engine compartment very well.
In that popularity ebay is full of cheap import knock offs of the dual Spals, some work good some are just garbage, so if I was to consider the dual 11" Spals I would be sure to get the real name brand or a knock off I new was up to par.
The Dual 11" Spals move about 2780 CFM of air according to spal which is on the low side according to most electric fan manufactures for a car like a Corvette which they recommend at least 3500 CFM.
So how do Dual 11" spals cool so many high demand applications so well?
In all the cases I know of the dual 11" Spals are being adding to aftermarket Aluminum radiators which are actually larger than needed to cool most of the 68-82 Corvette they are on, since the radiator can cool more they get by with a little less air flow from the Spals.
There are other dual fans that move more CFM of air and cover more of the radiator core than the dual 11" Spals such as models from Derale fans, prices seem competitive with the Spals.
Shroud designs,
Even the stock engine driven fan will do very little if the shroud isn't up to par with seals in place and fan spaced correctly,
Electric fan shroud designs vary, but even the single fans have a shroud built around them, dual fans like the Derale or Spals have a duplex shroud, some are open where the blades are and some are divided keeping each side separated.
The simple fact is the fan is only really moving air where is sits on the radiator, for example if I have a radiator 26" x 17" radiator core and a single round 10" electric fan in the center the only air it's pulling is in the 10" circle, easy to see why the more radiator core covered the better as far as efficiency goes, if for example I have dual fans in a duplex shroud and it covers 24" x 12" some radiator core is wasted to a degree, I have seen some clever fabricators extend the shroud to fully cover the radiator.
I have also been told and seen that full coverage isn't needed in the case of the larger aftermarket radiators. ( I am too OCD to waste expensive radiator )
Most larger duplex shrouds have trap doors in them to allow air at speeds to better flow through.
Controllers,
The sky is almost the limit, the factory many times would have the switch temp so high by the time the fans came on the vehicle was already creeping up higher than many people desire, in general one desires the fans to come on just after the thermostat opens for example if you have a 180 thermostat then you want your fan switch to trigger at 190 or a little higher, since the heated coolant is now circulating we need flow to cool it. then if two speeds, 200-210 is about right for high, why let things creep up near overheated temperatures if we do not have to.
Much of this is dictated by the climate of the area, the car is and builders desires...there is no blanket right answer here.
Some people like the high end computer fan controllers, some have fan controls on things like FI and others use lower end temp switches and relay set ups in all cases the fans power leads need to be fused and run through a relay.
Some Taurus fans are single fan dual speeds, the wiring requires relays or a controller that when high is triggered the low power wire doesn't see power.
In the case of dual fans there are many ways to wire it and no one way is 100% right for each person, a builder must decide which is right for them.
One way is both fans come on when the trigger temp is reached, straight up and simple.
a grounding temperature switch is in the engine head, block, intake etc, and when it reaches temperature it send a ground signal to the relay to turn on the fan.
Another way is one fan comes on for low then both fans on for high,
This doesn't work as well on duplex shrouds without the divider because a fan will try to pull from least resistant and that will be the hole of the non running fan, and even with a divided shroud with only one fan on it's basically only pulling from the area it covers.
On the flip side many people use generic single fans fitting two or I have seen 3 on the radiator and run one for low both for high and it works fine again due to the area of radiator it is pulling through is enough to keep things cool.
What GM uses on lot of modern cars is both fans on at low speed wired is series both fans are getting 1/2 power, then when high temp is triggered they switch to parallel wiring and both are getting full power.
Again, all power leads need to be fused and fan supply need relays.
In addition some builders like override switches to turn fans on and off at any time they desire and some like the fans to come on with AC compressor, in most cases that keeps the fans on at higher speeds when not needed a solution to this is wiring the AC override to an AC trinary switch and then it only switches on when needed.
Some people wire to allow the fans to run after the car is shut off with the idea it helps cool the engine compartment, ever seen the warning decals on late models that say "fan may start at any time" this type wiring is what that is from.
I would consider a very important part of adding electric fans is choosing ones with a high CFM rating, if adding to a stock radiator this rating is going to need to be higher than if added to an oversized aftermarket aluminum radiator.
( Please note some fans manufactures measure CFM with no "load" or radiator in front of it, so when the imports brag their 10" fan moves 3000 CFM this is why. )
Another thing to think about is the "zip tie" mounting to the radiator core, this is a quick easy way to mount electric fans and some people get away with it,
I believe it is just asking for core leaks.
Hopefully I shined a little light and made some food for thought.
The following 4 users liked this post by The13Bats:
08-21-2016, 07:13 AM
#5
Le Mans Master
Check out some bigger names like Spal or derale...
The posts on electric fans seem to get as "heated" as the Radiator posts.
I have been working on my little write ups to try to help I am no guru on the subjects but do research things I post about it and try to keep in what is on this forum the most.
Please see if this helps any, work in progress...
The posts on electric fans seem to get as "heated" as the Radiator posts.
I have been working on my little write ups to try to help I am no guru on the subjects but do research things I post about it and try to keep in what is on this forum the most.
Please see if this helps any, work in progress...
08-21-2016, 09:15 PM
#6
Race Director
The purpose of the fan be it electric or engine driven is to cool in this case the corvette at idle and at low speeds, if the cooling system is up to par and all the seals and so forth in place the stock engine driven fan has proven to work very well for many decades.
AGREED
So why swap to an electric fan?
Reasons can range from cooling problems which in that case just adding an electric fan would be a band-aid not a solution and likely not help to people who like to update and upgrade,
AGREED there is often another problem that is not being corrected.
Some electric fan companies say you can get an increase of both HP and MPG but in a Corvette that will likely be rather nominal
AGREED...I would also need to see data proving that type of statement. The only immediate gain would be not having a fan clutch/fan on the water pump taking power to turn it.
If you are considering electric fans also consider you will need to upgrade your charging system, while I personally like more it would seem that an over 100 amp Alternator is the least one should consider, in that a larger gauge charging wire is also needed.
AGREED. Using the current alternator can be a recipe for disaster of some level.
There are some people who like a single fan others like dual fans and some people even run 3 fans, lots of ways to get the desired results.
AGREED
Electric fans, there are a lot to chose from and the pot keeps getting bigger,
Some people like to use fans from other cars like the two speed Taurus fan or mark IV but these are not without the drawbacks of some fabrication to get them to mount to the 68-82 radiator, they do move a lot of air and people who use then are happy.
AGREED...using parts from another auto manufacturer can require some modifications.
Some have flat blades which are said to move more air than the curved blades which do not make as much noise.
Would have to see data on that. I have not yet had two exactly the same fans. One with flat blades and one with curved blades where I can use my air flow meter and check them. I am more concerned that I am getting enough air. BUT this is interesting and if I am lucky to get two fans with different design blades...I will check it out.
If money is no object then a look at the new brush less designs might be in order, they do work very well and far more efficient than older motor designs.
AGREED...but I have some brushless fan motors for the fans in my shop and they can also go bad. It basically deals with the bearings that the shaft spins on gets 'funky'
Very popular is the dual 11" Spals and they are proven to cool some high HP engine in hot conditions, even though Spal recommends them for "small V8's" and their shroud fails to cover the full 68-82 Corvette radiator core, however they do fit the cramped 68-82 engine compartment very well.
AGREED...and even with the fan shroud not fully covering the core of the radiator...it does not effect the performance of what the fans can provide. So this design characteristic is seeming a person preference issue.
In that popularity ebay is full of cheap import knock offs of the dual Spals, some work good some are just garbage, so if I was to consider the dual 11" Spals I would be sure to get the real name brand or a knock off I new was up to par.
AGREED...gotta watch what you buy and what you think you are getting. Saving money on a cheap knock-off may come back and haunt you later.
The Dual 11" Spals move about 2780 CFM of air according to spal which is on the low side according to most electric fan manufactures for a car like a Corvette which they recommend at least 3500 CFM.
So how do Dual 11" spals cool so many high demand applications so well?
In all the cases I know of the dual 11" Spals are being adding to aftermarket Aluminum radiators which are actually larger than needed to cool most of the 68-82 Corvette they are on, since the radiator can cool more they get by with a little less air flow from the Spals.
In all cases you know of may be true....BUT...in my case...which you are aware of......for your write up...NOT all of the aluminum radiators I install are going into a Corvette where the new aluminum radiator is actually larger than what was originally in it. The 1974 radiator I changed out was the exact same size with twin SPAL fans. So for whatever this is worth...the SPAL fans work just fine.
There are other dual fans that move more CFM of air and cover more of the radiator core than the dual 11" Spals such as models from Derale fans, prices seem competitive with the Spals.
This may be true...and seems to be a 'personal preference thing' to the person purchasing/installing the electric fan due to if both work...then a person can have a choice. And depending on the requirements for the engine being cooled...more CFM may be needed.
Shroud designs,
Even the stock engine driven fan will do very little if the shroud isn't up to par with seals in place and fan spaced correctly,
Electric fan shroud designs vary, but even the single fans have a shroud built around them, dual fans like the Derale or Spals have a duplex shroud, some are open where the blades are and some are divided keeping each side separated.
AGREED...different philosophies on how they design their products.
The simple fact is the fan is only really moving air where is sits on the radiator, for example if I have a radiator 26" x 17" radiator core and a single round 10" electric fan in the center the only air it's pulling is in the 10" circle, easy to see why the more radiator core covered the better as far as efficiency goes, if for example I have dual fans in a duplex shroud and it covers 24" x 12" some radiator core is wasted to a degree, I have seen some clever fabricators extend the shroud to fully cover the radiator.
I have also been told and seen that full coverage isn't needed in the case of the larger aftermarket radiators. ( I am too OCD to waste expensive radiator )
Most larger duplex shrouds have trap doors in them to allow air at speeds to better flow through.
AGREED..so 100% completely covering the core is obviously NOT needed in all applications.
Controllers,
The sky is almost the limit, the factory many times would have the switch temp so high by the time the fans came on the vehicle was already creeping up higher than many people desire, in general one desires the fans to come on just after the thermostat opens for example if you have a 180 thermostat then you want your fan switch to trigger at 190 or a little higher, since the heated coolant is now circulating we need flow to cool it. then if two speeds, 200-210 is about right for high, why let things creep up near overheated temperatures if we do not have to.
Much of this is dictated by the climate of the area, the car is and builders desires...there is no blanket right answer here.
AGREED...because GM has it to where the cooling fan will come on at 226-228 degrees F on some year models of Corvettes.
Some people like the high end computer fan controllers, some have fan controls on things like FI and others use lower end temp switches and relay set ups in all cases the fans power leads need to be fused and run through a relay.
Some Taurus fans are single fan dual speeds, the wiring requires relays or a controller that when high is triggered the low power wire doesn't see power.
In the case of dual fans there are many ways to wire it and no one way is 100% right for each person, a builder must decide which is right for them.
AGREED
One way is both fans come on when the trigger temp is reached, straight up and simple.
a grounding temperature switch is in the engine head, block, intake etc, and when it reaches temperature it send a ground signal to the relay to turn on the fan.
AGREED..this is obviously one wiring method
Another way is one fan comes on for low then both fans on for high,
AGREED..if wired that way for teh builders needs.
This doesn't work as well on duplex shrouds without the divider because a fan will try to pull from least resistant and that will be the hole of the non running fan, and even with a divided shroud with only one fan on it's basically only pulling from the area it covers.
AGREED
On the flip side many people use generic single fans fitting two or I have seen 3 on the radiator and run one for low both for high and it works fine again due to the area of radiator it is pulling through is enough to keep things cool.
Obviously they have found a way.
What GM uses on lot of modern cars is both fans on at low speed wired is series both fans are getting 1/2 power, then when high temp is triggered they switch to parallel wiring and both are getting full power.
Again, all power leads need to be fused and fan supply need relays.
AGREED. But earlier years did not do this and worked just fine also.
In addition some builders like override switches to turn fans on and off at any time they desire and some like the fans to come on with AC compressor, in most cases that keeps the fans on at higher speeds when not needed a solution to this is wiring the AC override to an AC trinary switch and then it only switches on when needed.
AGREED...This is also a personal choice. There is not specific set-up that is correct across the board.
Some people wire to allow the fans to run after the car is shut off with the idea it helps cool the engine compartment, ever seen the warning decals on late models that say "fan may start at any time" this type wiring is what that is from.
AGREED...a personal choice to lower engine compartment temps.
I would consider a very important part of adding electric fans is choosing ones with a high CFM rating, if adding to a stock radiator this rating is going to need to be higher than if added to an oversized aftermarket aluminum radiator.
SUBJECTIVE comment here. Because if you already have a large copper brass radiator that can not be enlarged...this comment does not fit.
( Please note some fans manufactures measure CFM with no "load" or radiator in front of it, so when the imports brag their 10" fan moves 3000 CFM this is why. )
AGREED...you must look through the 'smoke and mirrors' sometimes.
Another thing to think about is the "zip tie" mounting to the radiator core, this is a quick easy way to mount electric fans and some people get away with it,
I believe it is just asking for core leaks.
AGREED...those 'zip-tie' mounts make me NERVOUS and I personally think they are a cheap incorrect method of installing a fan.
Hopefully I shined a little light and made some food for thought
For the most part and you can see...I agree with this.. this should help many who may have concerns of some type.
DUB
AGREED
So why swap to an electric fan?
Reasons can range from cooling problems which in that case just adding an electric fan would be a band-aid not a solution and likely not help to people who like to update and upgrade,
AGREED there is often another problem that is not being corrected.
Some electric fan companies say you can get an increase of both HP and MPG but in a Corvette that will likely be rather nominal
AGREED...I would also need to see data proving that type of statement. The only immediate gain would be not having a fan clutch/fan on the water pump taking power to turn it.
If you are considering electric fans also consider you will need to upgrade your charging system, while I personally like more it would seem that an over 100 amp Alternator is the least one should consider, in that a larger gauge charging wire is also needed.
AGREED. Using the current alternator can be a recipe for disaster of some level.
There are some people who like a single fan others like dual fans and some people even run 3 fans, lots of ways to get the desired results.
AGREED
Electric fans, there are a lot to chose from and the pot keeps getting bigger,
Some people like to use fans from other cars like the two speed Taurus fan or mark IV but these are not without the drawbacks of some fabrication to get them to mount to the 68-82 radiator, they do move a lot of air and people who use then are happy.
AGREED...using parts from another auto manufacturer can require some modifications.
Some have flat blades which are said to move more air than the curved blades which do not make as much noise.
Would have to see data on that. I have not yet had two exactly the same fans. One with flat blades and one with curved blades where I can use my air flow meter and check them. I am more concerned that I am getting enough air. BUT this is interesting and if I am lucky to get two fans with different design blades...I will check it out.
If money is no object then a look at the new brush less designs might be in order, they do work very well and far more efficient than older motor designs.
AGREED...but I have some brushless fan motors for the fans in my shop and they can also go bad. It basically deals with the bearings that the shaft spins on gets 'funky'
Very popular is the dual 11" Spals and they are proven to cool some high HP engine in hot conditions, even though Spal recommends them for "small V8's" and their shroud fails to cover the full 68-82 Corvette radiator core, however they do fit the cramped 68-82 engine compartment very well.
AGREED...and even with the fan shroud not fully covering the core of the radiator...it does not effect the performance of what the fans can provide. So this design characteristic is seeming a person preference issue.
In that popularity ebay is full of cheap import knock offs of the dual Spals, some work good some are just garbage, so if I was to consider the dual 11" Spals I would be sure to get the real name brand or a knock off I new was up to par.
AGREED...gotta watch what you buy and what you think you are getting. Saving money on a cheap knock-off may come back and haunt you later.
The Dual 11" Spals move about 2780 CFM of air according to spal which is on the low side according to most electric fan manufactures for a car like a Corvette which they recommend at least 3500 CFM.
So how do Dual 11" spals cool so many high demand applications so well?
In all the cases I know of the dual 11" Spals are being adding to aftermarket Aluminum radiators which are actually larger than needed to cool most of the 68-82 Corvette they are on, since the radiator can cool more they get by with a little less air flow from the Spals.
In all cases you know of may be true....BUT...in my case...which you are aware of......for your write up...NOT all of the aluminum radiators I install are going into a Corvette where the new aluminum radiator is actually larger than what was originally in it. The 1974 radiator I changed out was the exact same size with twin SPAL fans. So for whatever this is worth...the SPAL fans work just fine.
There are other dual fans that move more CFM of air and cover more of the radiator core than the dual 11" Spals such as models from Derale fans, prices seem competitive with the Spals.
This may be true...and seems to be a 'personal preference thing' to the person purchasing/installing the electric fan due to if both work...then a person can have a choice. And depending on the requirements for the engine being cooled...more CFM may be needed.
Shroud designs,
Even the stock engine driven fan will do very little if the shroud isn't up to par with seals in place and fan spaced correctly,
Electric fan shroud designs vary, but even the single fans have a shroud built around them, dual fans like the Derale or Spals have a duplex shroud, some are open where the blades are and some are divided keeping each side separated.
AGREED...different philosophies on how they design their products.
The simple fact is the fan is only really moving air where is sits on the radiator, for example if I have a radiator 26" x 17" radiator core and a single round 10" electric fan in the center the only air it's pulling is in the 10" circle, easy to see why the more radiator core covered the better as far as efficiency goes, if for example I have dual fans in a duplex shroud and it covers 24" x 12" some radiator core is wasted to a degree, I have seen some clever fabricators extend the shroud to fully cover the radiator.
I have also been told and seen that full coverage isn't needed in the case of the larger aftermarket radiators. ( I am too OCD to waste expensive radiator )
Most larger duplex shrouds have trap doors in them to allow air at speeds to better flow through.
AGREED..so 100% completely covering the core is obviously NOT needed in all applications.
Controllers,
The sky is almost the limit, the factory many times would have the switch temp so high by the time the fans came on the vehicle was already creeping up higher than many people desire, in general one desires the fans to come on just after the thermostat opens for example if you have a 180 thermostat then you want your fan switch to trigger at 190 or a little higher, since the heated coolant is now circulating we need flow to cool it. then if two speeds, 200-210 is about right for high, why let things creep up near overheated temperatures if we do not have to.
Much of this is dictated by the climate of the area, the car is and builders desires...there is no blanket right answer here.
AGREED...because GM has it to where the cooling fan will come on at 226-228 degrees F on some year models of Corvettes.
Some people like the high end computer fan controllers, some have fan controls on things like FI and others use lower end temp switches and relay set ups in all cases the fans power leads need to be fused and run through a relay.
Some Taurus fans are single fan dual speeds, the wiring requires relays or a controller that when high is triggered the low power wire doesn't see power.
In the case of dual fans there are many ways to wire it and no one way is 100% right for each person, a builder must decide which is right for them.
AGREED
One way is both fans come on when the trigger temp is reached, straight up and simple.
a grounding temperature switch is in the engine head, block, intake etc, and when it reaches temperature it send a ground signal to the relay to turn on the fan.
AGREED..this is obviously one wiring method
Another way is one fan comes on for low then both fans on for high,
AGREED..if wired that way for teh builders needs.
This doesn't work as well on duplex shrouds without the divider because a fan will try to pull from least resistant and that will be the hole of the non running fan, and even with a divided shroud with only one fan on it's basically only pulling from the area it covers.
AGREED
On the flip side many people use generic single fans fitting two or I have seen 3 on the radiator and run one for low both for high and it works fine again due to the area of radiator it is pulling through is enough to keep things cool.
Obviously they have found a way.
What GM uses on lot of modern cars is both fans on at low speed wired is series both fans are getting 1/2 power, then when high temp is triggered they switch to parallel wiring and both are getting full power.
Again, all power leads need to be fused and fan supply need relays.
AGREED. But earlier years did not do this and worked just fine also.
In addition some builders like override switches to turn fans on and off at any time they desire and some like the fans to come on with AC compressor, in most cases that keeps the fans on at higher speeds when not needed a solution to this is wiring the AC override to an AC trinary switch and then it only switches on when needed.
AGREED...This is also a personal choice. There is not specific set-up that is correct across the board.
Some people wire to allow the fans to run after the car is shut off with the idea it helps cool the engine compartment, ever seen the warning decals on late models that say "fan may start at any time" this type wiring is what that is from.
AGREED...a personal choice to lower engine compartment temps.
I would consider a very important part of adding electric fans is choosing ones with a high CFM rating, if adding to a stock radiator this rating is going to need to be higher than if added to an oversized aftermarket aluminum radiator.
SUBJECTIVE comment here. Because if you already have a large copper brass radiator that can not be enlarged...this comment does not fit.
( Please note some fans manufactures measure CFM with no "load" or radiator in front of it, so when the imports brag their 10" fan moves 3000 CFM this is why. )
AGREED...you must look through the 'smoke and mirrors' sometimes.
Another thing to think about is the "zip tie" mounting to the radiator core, this is a quick easy way to mount electric fans and some people get away with it,
I believe it is just asking for core leaks.
AGREED...those 'zip-tie' mounts make me NERVOUS and I personally think they are a cheap incorrect method of installing a fan.
Hopefully I shined a little light and made some food for thought
For the most part and you can see...I agree with this.. this should help many who may have concerns of some type.
DUB
08-21-2016, 09:23 PM
#7
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DUB and company... Feel free to contribute to the new aluminum radiator and related topic Sticky in C3 Tech :
https://www.corvetteforum.com/forums...ed-topics.html
https://www.corvetteforum.com/forums...ed-topics.html
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DUB (08-22-2016)
08-21-2016, 09:29 PM
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Thanks dub glad you liked it....
for clarification I answered the points of your concerns, I did this write up just try to help people and to try to step away for the endless pointless back and forths and can only hope for some it does that if not so be it.
So after this reply allow me to just step back and not do the very thing I was trying to help prevent.
Some have flat blades which are said to move more air than the curved blades which do not make as much noise.
My "in general" statement comes from the manufactures of the fans and I believe their engineers and designers on it, if you want to take the next step and test their claims please post that data at that time,
I would believe that some modern curved blades do move more air than the older straight designs and do it with less noise, a best of both worlds idea, I was trying to keep it simple in my write up.
In all the cases I know of the dual 11" Spals are being adding to aftermarket Aluminum radiators which are actually larger than needed to cool most of the 68-82 Corvette they are on, since the radiator can cool more they get by with a little less air flow from the Spals.
Neither one of us have listed how many radiators we have worked with.
I have stated previously that the dual 11" Spals do cool stock to mild shark corvettes, which feedback shows they do.
If a radiator is replaced in most cases the old one is defective, otherwise why change it if it's not broken?
If that change is to a new stock one the dual 11" Spals will likely cool it, even though Spal as a company recommends a larger CFM rating.
There are other dual fans that move more CFM of air and cover more of the radiator core than the dual 11" Spals such as models from Derale fans, prices seem competitive with the Spals.
My statement is true, there are other electric fans that do move more CFM of air and do cover more of the 68-82 radiator core,
I hate to repeat things but even Spal recommend a larger fan for the 68-82 corvettes, but for many it works,
For some we do desire or need a fan that moves more CFM in my case I just like the peace of mind to have more than I might need than just enough, and agreed that is personal preference.
I would consider a very important part of adding electric fans is choosing ones with a high CFM rating, if adding to a stock radiator this rating is going to need to be higher than if added to an oversized aftermarket aluminum radiator.
I believe the comment fits in context,
In my write up many things I wrote are "in general" to keep it simple.
If you already run the largest copper radiator and are having cooling issues then switching to a larger aluminum radiator is what many seem to try.
when I said "high" rating that was in relation to a low rating and all the fan manufactory suggest 3000-4000 CFM for cars like the 68-82 Corvettes.
So my comment was related to if a person has an oversized aftermarket aluminum radiator it will cool better than a stock copper radiator and be more forgiving of fans of smaller CFM, and in most cases if the person has a copper radiator it would be wise to increase fan CFM at least to what is recommend by the companies who make the fans.
for clarification I answered the points of your concerns, I did this write up just try to help people and to try to step away for the endless pointless back and forths and can only hope for some it does that if not so be it.
So after this reply allow me to just step back and not do the very thing I was trying to help prevent.
Some have flat blades which are said to move more air than the curved blades which do not make as much noise.
Would have to see data on that. I have not yet had two exactly the same fans. One with flat blades and one with curved blades where I can use my air flow meter and check them. I am more concerned that I am getting enough air. BUT this is interesting and if I am lucky to get two fans with different design blades...I will check it out.
I would believe that some modern curved blades do move more air than the older straight designs and do it with less noise, a best of both worlds idea, I was trying to keep it simple in my write up.
In all the cases I know of the dual 11" Spals are being adding to aftermarket Aluminum radiators which are actually larger than needed to cool most of the 68-82 Corvette they are on, since the radiator can cool more they get by with a little less air flow from the Spals.
In all cases you know of may be true....BUT...in my case...which you are aware of......for your write up...NOT all of the aluminum radiators I install are going into a Corvette where the new aluminum radiator is actually larger than what was originally in it. The 1974 radiator I changed out was the exact same size with twin SPAL fans. So for whatever this is worth...the SPAL fans work just fine.
I have stated previously that the dual 11" Spals do cool stock to mild shark corvettes, which feedback shows they do.
If a radiator is replaced in most cases the old one is defective, otherwise why change it if it's not broken?
If that change is to a new stock one the dual 11" Spals will likely cool it, even though Spal as a company recommends a larger CFM rating.
There are other dual fans that move more CFM of air and cover more of the radiator core than the dual 11" Spals such as models from Derale fans, prices seem competitive with the Spals.
This may be true...and seems to be a 'personal preference thing' to the person purchasing/installing the electric fan due to if both work...then a person can have a choice. And depending on the requirements for the engine being cooled...more CFM may be needed.
I hate to repeat things but even Spal recommend a larger fan for the 68-82 corvettes, but for many it works,
For some we do desire or need a fan that moves more CFM in my case I just like the peace of mind to have more than I might need than just enough, and agreed that is personal preference.
I would consider a very important part of adding electric fans is choosing ones with a high CFM rating, if adding to a stock radiator this rating is going to need to be higher than if added to an oversized aftermarket aluminum radiator.
SUBJECTIVE comment here. Because if you already have a large copper brass radiator that can not be enlarged...this comment does not fit.
In my write up many things I wrote are "in general" to keep it simple.
If you already run the largest copper radiator and are having cooling issues then switching to a larger aluminum radiator is what many seem to try.
when I said "high" rating that was in relation to a low rating and all the fan manufactory suggest 3000-4000 CFM for cars like the 68-82 Corvettes.
So my comment was related to if a person has an oversized aftermarket aluminum radiator it will cool better than a stock copper radiator and be more forgiving of fans of smaller CFM, and in most cases if the person has a copper radiator it would be wise to increase fan CFM at least to what is recommend by the companies who make the fans.
Last edited by The13Bats; 08-22-2016 at 10:52 PM.
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The13Bats (08-21-2016)
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08-22-2016, 12:16 AM
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08-22-2016, 06:17 PM
#12
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I have gone to the 'sticky thread' and leaving this one. I wrote all I needed to write on this one.
What you wrote is what you wrote...and I was NOT bashing you...just commenting on several areas that your raised that are worthy of further investigation.
DUB
What you wrote is what you wrote...and I was NOT bashing you...just commenting on several areas that your raised that are worthy of further investigation.
DUB
08-22-2016, 10:50 PM
#13
Instructor
just going to say it now, Mark VIII fan. stock fan that was built for a large multi platform fleet. made to last with maximum cooling. im doing this right now and i feel like its the way to go
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The13Bats (08-22-2016)
08-22-2016, 11:06 PM
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I would love for you to do a write up on this subject with pictures.
perhaps cover the different Mark fans, they mixed and matched motors and blades, some years make models better than others, what was needed as far as modifications to fit the 68-82 etc,
I saw one on here years ago the fellow made a whole new shroud to fit his radiator using the mark motor and fan.
08-22-2016, 11:19 PM
#15
Instructor
This was a super popular swap years ago which pops up on here from time to time and many non corvette people still use this and that Taurus 2 speed I messed with, these fans put out huge CFM and are cheap.
I would love for you to do a write up on this subject with pictures.
perhaps cover the different Mark fans, they mixed and matched motors and blades, some years make models better than others, what was needed as far as modifications to fit the 68-82 etc,
I saw one on here years ago the fellow made a whole new shroud to fit his radiator using the mark motor and fan.
I would love for you to do a write up on this subject with pictures.
perhaps cover the different Mark fans, they mixed and matched motors and blades, some years make models better than others, what was needed as far as modifications to fit the 68-82 etc,
I saw one on here years ago the fellow made a whole new shroud to fit his radiator using the mark motor and fan.
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The13Bats (08-22-2016)
08-22-2016, 11:31 PM
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you know, i was thinking about making two mega threads that cover everything you need to know on a swap. i just did a hydroboost conversion and i had a few problems on the way, but havent even been able to drive it yet because now im working on the cooling system so that i can keep the car from over heating after i rebuilt the top end. but i think im going to make at least the Mark VIII thread as long as people want it. then allow others to put up info so that i can add it and edit the original thread. i paid 62 bucks for my fan and after looking at what everyone else has done in the jeep world and mustangs, i feel like its a fairly safe mod that offers a lot for the work and money put into it
The mark fan has proven itself over and over, in many cars.
Please try to also do pictures which will really make it sweet,
I believe this is a mod a lot of people would do if they have a write up to see what they are up against.
Perhaps it could become a sticky
I do not run the hydroboost but it too is a popular subject that still has an air of mystique for some of us,
A step by step thread with the issues you had and how you solved the problems would also be a great one to write up....
08-23-2016, 06:51 PM
#17
Race Director
you know, i was thinking about making two mega threads that cover everything you need to know on a swap. i just did a hydroboost conversion and i had a few problems on the way, but havent even been able to drive it yet because now im working on the cooling system so that i can keep the car from over heating after i rebuilt the top end. but i think im going to make at least the Mark VIII thread as long as people want it. then allow others to put up info so that i can add it and edit the original thread. i paid 62 bucks for my fan and after looking at what everyone else has done in the jeep world and mustangs, i feel like its a fairly safe mod that offers a lot for the work and money put into it
DUB
08-23-2016, 08:37 PM
#18
Instructor
Dub, do you have any photos from your build? I don't have any from threading the Hydroboost, and cutting the eye off. I feel if we make a thread that will cover everything you need, people will make the switch.
08-24-2016, 06:33 PM
#20
Race Director
I am sure I can get the car in the shop and take photos. But usually I am not taking pictures of everything I do. I can not remember if I took photos and e-mailed them to my customer...but I will look.
I am actually 'spoiled' when I do these. The customer that I have done them for buys the 'kit' from HydraTech...so it is ready to bolt to the firewall. The only changes I do are the fittings are changed due to I do not want to use rubber hoses and regular hose clamps....I want better looking hoses and AN fittings.
Then I machine out custom hose holders so I can correctly route the hoses away from the LS exhaust and secure it to the frame These are being installed on resto-mods.
DUB
Last edited by DUB; 08-24-2016 at 06:34 PM.
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The13Bats (08-24-2016)