When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Checked the stickies, ran a search, no luck.
Question:
550 HP w/AC, automatic, alum rad.
Which is better?
Dual Spal 11's with shroud or One Spal 16"
As The13Bats pointed out in a post I read, the active fan will draw air from the inactive fans opening when running duals sharing a shroud.... makes sense to me. So unless they're both on, not so good. Why not just run the high torque 16" fan then? Just need one harness, one relay, etc. Can the dual 11's cool as good as the single 16?? The dual 11 setup I saw stated "up to 400 HP" and "1000 HP" for the 16" yet from what I can tell most of you seem to prefer the duals. Is that because your HP levels are 400 or less??
Thanks,
Jim
Last edited by jimvette999; 05-04-2017 at 08:47 AM.
Reason: corrected member's name
Cfm is what matters. A shroud can help to spread the airflow across the surface of the radiator, but with enough cfm I'm not convinced how necessary it is, and it almost certainly reduces airflow at speed. My 16" Spal without shroud on a very good alloy radiator happily cools my ~500hp stroker small block even in traffic on the hottest days we have here (around 110-115F). To me, assuming the same cfm, I can't see the advantage of the twin 11"s, apart from possibly the redundancy if one fails.
Last edited by Metalhead140; 05-03-2017 at 10:09 PM.
Which 11" vs which 16" exactly? There are multiples of each version.
Where did you find HP ratings?
If you want to compare then look at the CFM values for various pressures. For dual 11" fans double the 11" fan CFM numbers. I think you'll find that 2 good 11" fans flow more air that a single 16" fan.
As for running a single fan in a dual fan setup. Just don't do it. Either run both fans with a PWM controller or wire them with 3 relays so they will both run in a low/high speed configuration.
Which 11" vs which 16" exactly? There are multiples of each version.
Where did you find HP ratings?
If you want to compare then look at the CFM values for various pressures. For dual 11" fans double the 11" fan CFM numbers. I think you'll find that 2 good 11" fans flow more air that a single 16" fan.
As for running a single fan in a dual fan setup. Just don't do it. Either run both fans with a PWM controller or wire them with 3 relays so they will both run in a low/high speed configuration.
Absolutely... Looking on Summit, you can buy a ~2000cfm 16" Spal for $151, a 3000cfm 16" Spal for $188, or a pair of 11" Spals on a shroud pulling 2700cfm for $338. I went for the first option, works fine for me, but the second option makes more sense than the third to me, if you want/need more cfm.
Checked the stickies, ran a search, no luck.
Question:
550 HP w/AC, automatic, alum rad.
Which is better?
Dual Spal 11's with shroud or One Spal 16"
As 13 Bats pointed out in a post I read, the active fan will draw air from the inactive fans opening when running duals sharing a shroud.... makes sense to me. So unless they're both on, not so good. Why not just run the high torque 16" fan then? Just need one harness, one relay, etc. Can the dual 11's cool as good as the single 16?? The dual 11 setup I saw stated "up to 400 HP" and "1000 HP" for the 16" yet from what I can tell most of you seem to prefer the duals. Is that because your HP levels are 400 or less??
Thanks,
Jim
I had one 16 and realized that I don't always need max CFM. The choices for dual capacity is 1 fan with 2 speeds or 2 fans that turn on at different temperatures as needed.
Here's a picture of my dual 11" system with the controller that turns the fans on and off in sequence when necessary.
I am SO glad I switched to dual 11's. If one fan does the job, then the other doesn't even come in.
Whatever "CFM" you have with your fan[s], that CFM has to flow through the radiator...instead of around it. You NEED a good shroud and you NEED good seals to make sure that air is only coming through the rad.
Agreed that the air needs to go through the rad, and you need good seals. In terms of shroud, that depends what you mean. You don't need (in my opinion and experience) a shroud to make the fan pull from across the entire radiator core surface. You do need some sort of shroud around the tips of the fan blades to make the fan effective, but every aftermarket electric radiator fan I've seen for years has that built in. You do need the fan either mounted up against or sealed/shrouded to the radiator core so that air flowing through the fan has to come through the radiator and cannot be pulled around the sides of the fan. You definitely want the radiator to support seals in place.
Last edited by Metalhead140; 05-04-2017 at 12:32 AM.
Some dual fans do not have a divider built in while others do, the ones with a devider you can run for example, one fan for low both for high.
A shroud is very important and contrary to what you said motorhead your fan does have a shroud in the ring around the blades,
I have not seen any electric fans made for cars radiators with no shroud at all since the one on my valkyrie kit car which was built in the 60s,
On a fan like that only place air is being being pulled through at idle or below speeds is the circle of that fan, some c radiator is wasted, perhaps you dont need more, im too OCD to waste radiator.
Most all electric fan companied agree you need about 3000 to 3500k to cool a small block, people get away with less fan when they have oversized radiators
Great example dual spal 11s which even spal says are small for a v8 cool great on members cars who have radiators like dewitts or champion
I have a FI 350 engine, serp drive, and a '89 F body rad in my '72.....with a/c.......in FLORIDA....the dual Spals are run by the computer and a relay on top of the shroud, and wiring straight from the alt output stud...run up/over to the relay, nice thick heavy wire with an inline 30 amp blade fuse in holder....
the Spal shroud is almost the size of the rad, so when installing this setup, I pulled the support and installed a couple of aluminum L braces from hardware store....from the back edge of the rad mount brackets, and the fans are held to those cross pieces....and the edges stuffed with pipe wrap foam like around the entire radiator.....a piece of aluminum flashing is held along the bottom edge bolted in between the fans and the cross piece, and goes down to the bottom edge of the install, ensuring complete airflow through the radiator.....
I know it looks a bit sloppy, but several pieces of pipe wrap are glued to the top of the rad support to ensure that at speed, the air is forced through the rad and not up/over the top....
FLORIDA demands extra care....BTW the rad is single row, plastic tanks, and only about 1.5 inches thick at most....
Cfm is what matters. A shroud can help to spread the airflow across the surface of the radiator, but with enough cfm I'm not convinced how necessary it is, and it almost certainly reduces airflow at speed. My 16" Spal without shroud on a very good alloy radiator happily cools my ~500hp stroker small block even in traffic on the hottest days we have here (around 110-115F). To me, assuming the same cfm, I can't see the advantage of the twin 11"s, apart from possibly the redundancy if one fails.
Redundancy was what I had assumed the appeal was too. Encouraged to know the 16 handles your engine in that heat...do you run AC? Automatic?
Thank you.
Originally Posted by lionelhutz
Which 11" vs which 16" exactly? There are multiples of each version.
Where did you find HP ratings?
If you want to compare then look at the CFM values for various pressures. For dual 11" fans double the 11" fan CFM numbers. I think you'll find that 2 good 11" fans flow more air that a single 16" fan.
As for running a single fan in a dual fan setup. Just don't do it. Either run both fans with a PWM controller or wire them with 3 relays so they will both run in a low/high speed configuration.
This is from the Be Cool site (that's my radiator brand)... they don't list CFM anywhere I could find.
Good advice I believe on running both on a PWM controller.
Thank you.
Originally Posted by Metalhead140
Absolutely... Looking on Summit, you can buy a ~2000cfm 16" Spal for $151, a 3000cfm 16" Spal for $188, or a pair of 11" Spals on a shroud pulling 2700cfm for $338. I went for the first option, works fine for me, but the second option makes more sense than the third to me, if you want/need more cfm.
I tend to overkill for peace of mind...I like option 2 also. I'm thinking I need north of 3000cfm. My radiator is sealed up and has the $175 stock clutch fan and sitting in summer heat with AC on it will creep to over 210*f. The AC is marginal when its condenser is in that heat range and the stock fan just doesn't pull enough air to cool condenser/radiator at idle IMO. Cools fine once I get moving. Using a Edelbrock high perf. alum. water pump, alum. block, alum heads, alum blower intake, aluminum everything.
Thank you.
Originally Posted by MN80Vette
I had one 16 and realized that I don't always need max CFM. The choices for dual capacity is 1 fan with 2 speeds or 2 fans that turn on at different temperatures as needed.
Here's a picture of my dual 11" system with the controller that turns the fans on and off in sequence when necessary.
I am SO glad I switched to dual 11's. If one fan does the job, then the other doesn't even come in.
That's a nice looking setup and good points in favor of duals.....just when I though I knew what I wanted.
Does yours have the divider between the fans that The13Bats mentioned?. It appears so. Your mounting kit, where is it from please?
Thank you.
Originally Posted by 7T1vette
Whatever "CFM" you have with your fan, that CFM has to flow through the radiator...instead of around it. You NEED a good shroud and you NEED good seals to make sure that air is only coming through the rad.
That makes sense, I currently have all the above, but my stock fan is just not enough in summer at idle with AC. I'll make sure to keep your recommendations with the new setup as well.
Thank you.
Originally Posted by The13Bats
Allow me to clarify,
Some dual fans do not have a divider built in while others do, the ones with a devider you can run for example, one fan for low both for high.
A shroud is very important and contrary to what you said motorhead your fan does have a shroud in the ring around the blades,
I have not seen any electric fans made for cars radiators with no shroud at all since the one on my valkyrie kit car which was built in the 60s,
On a fan like that only place air is being being pulled through at idle or below speeds is the circle of that fan, some c radiator is wasted, perhaps you dont need more, im too OCD to waste radiator.
Most all electric fan companied agree you need about 3000 to 3500k to cool a small block, people get away with less fan when they have oversized radiators
Great example dual spal 11s which even spal says are small for a v8 cool great on members cars who have radiators like dewitts or champion
I too would like to utilize as much of my radiator as possible for efficiency and reduced load on the electric fan.The single 16's don't seem to have radiator coverage, I guess because then they wouldn't fit all sizes of radiator shapes. A dual fan setup covers the radiator face nicely as in MN80Vette's ride but I'd want to wire them as suggested by lionelhutz to where they both run at the same time at variable speeds.
I have 406 cu. in. and still technically a small block but I have a better than stock radiator and still running hotter than I want at idle w/AC. They say you can run 220*-230*.... I want 180*-190* max.
You're a Kool Kat Bats. Love the customs like you do.
Thank you.
Originally Posted by mrvette
I have a FI 350 engine, serp drive, and a '89 F body rad in my '72.....with a/c.......in FLORIDA....the dual Spals are run by the computer and a relay on top of the shroud, and wiring straight from the alt output stud...run up/over to the relay, nice thick heavy wire with an inline 30 amp blade fuse in holder....
the Spal shroud is almost the size of the rad, so when installing this setup, I pulled the support and installed a couple of aluminum L braces from hardware store....from the back edge of the rad mount brackets, and the fans are held to those cross pieces....and the edges stuffed with pipe wrap foam like around the entire radiator.....a piece of aluminum flashing is held along the bottom edge bolted in between the fans and the cross piece, and goes down to the bottom edge of the install, ensuring complete airflow through the radiator.....
I know it looks a bit sloppy, but several pieces of pipe wrap are glued to the top of the rad support to ensure that at speed, the air is forced through the rad and not up/over the top....
FLORIDA demands extra care....BTW the rad is single row, plastic tanks, and only about 1.5 inches thick at most....
You always think out of the box and find a way to achieve your goals.
Thank you.
Thanks again to you guys for replying, really appreciate your input/advice.I'm still not sure what to do but I have more info to make a decision with. I sent email yesterday to Be Cool for advice on recommendation for fan,bracketry, and controllers so maybe they can tip the scales. I have no bung anywhere on my radaitor for a heat sensor....radiator is about 15 years old. Can't find receipt or anything about the model number or where I bought it.
Here's to all
Jim
Here's what Fred @ Be Cool had to say. I think he did a great job of answering my questions. I asked about the 16" and inquired if there was a better option to please advise. He did.
"Hello Jim,
The Be Cool Radiator part number would be 62029 with Internal Automatic Transmission Cooler.
Your Better Option Request;
· 75007 Dual 11” Shrouded Fans (2780 CFM @ 12 volts)
· 72038 Stainless Steel Fan Shroud Mounting Brackets with Hardware
· 75117 Dual Fans Wiring Harness with Temperature Sending Unit (on 195 off 175) and (2) 40 AMP Relays
· 75095 A/C Relay Harness with 40 AMP Relay
These items combined with your Radiator will cool up to 700 Dyno rated horsepower.
Thank You
Fred"
Last edited by jimvette999; 05-04-2017 at 09:55 AM.
Reason: took off non sponsoring vendor info from response
1. Draws way less current .. less than half!
2. A lot less noise, like half!
3. EMI is almost non existent.. VERY important for EFI guys
4. 1/3 the weight
5. no voltage/current surges on your system
6. Lasts years longer
7. Made in the USA
Or you can go cheap crap old tech brush fans.. I had the Spals for a while also... compared to the Delta PAG,,, yea, they are crap.
The brushless motor is the heart of the fan. It is constructed using high temp/high strength Neodymium magnets, hybrid ceramic bearings, stainless steel flux ring & multi-stranded "Litz" windings. The motor is very power dense, allowing for smaller construction, while generating high power. The operating life is conservatively rated at 30,000 hours. Please note, a typical brushed motor fan is rated at 2,000 hours.
Brushless DC (BLDC) motors offer several advantages over brushed DC motors. BLDCs are lighter and more efficient than conventional brushed motors, therefore reducing the energy consumption of the vehicle. As a result, Saving Gas! The elimination of brushes in a BLDC significantly increases motor reliability, reduces noise, reduces heat and increases efficiency due to the elimination of friction between the brushes and the commutator. Brushed DC motors have a typical efficiency of 70-75%, while a brushless DC motor can achieve 96% efficiency, a +28% improvement. While a brushed motor operates, sparks are created when the brushes rub against the commutator, this creates a fire hazard and produces EMI. BLDCs generate no sparks and significantly reduce interference emissions allowing for easier compliance with electromagnetic compatibility (EMC) requirements. Most modern vehicles incorporate computer controls in engine management and other general vehicle operations. Reducing electromagnetic interference (EMI) is critical for proper vehicle operation.
The BLDC motor has permanent magnets and flux ring which rotate around a fixed armature or stator, eliminating the problems of connecting current to the moving armature via brushes. The stator consists of a multiphase copper coil windings (U V W in figure 1) on a laminated core, and the rotor consists of permanent magnet segments or a molded ferrite ring that is attached at one end to the motor’s shaft. The stator windings are fed with electric currents controlled in magnitude and sequence (commutated) with pulse width modulation (PWM) to effect rotation of the rotor element just as in a typical brushed motor. Back-electromagnetic force (BEMF) is used for rotor positioning. This eliminates the need for hall sensors chips in the motor to identify the rotors position. These sensors are prone to burning out which limit the reliability of a motor. Since there are no sensors in our motor, the BLDC motor is called "sensor-less". This "commutation" is controlled by the electronic control module (ECM). All brushless motors require an ECM for operation.
Powerful: adjustable from 1,000 CFM to 2,800 CFM
Reliable: +50,000 hours operating life, 10x more than conventional fans
CFD optimized fan blade profile
Ultra-efficient: +20% improvement =
more power, less fuel consumption
Soft Start Technology eliminates power spikes
Easily replaceable control module
Self cooling technology = reliable, long
lasting operation
State-of-the-art tech, two patents awarded*
There have been SO many threads on this in the past. Ultimately you can get the CFM that you need in single or dual fans, but dual fans with dual relays and redundant wiring get you increased reliability if anything goes wrong, you still have enough cooling to get home without calling a tow truck, AAA, or using your Hagerty tow benefit for the year.
Dual fans pull significantly more amps, from the alternator, though; the single fan option is definitely more efficient if you plan to have a lot of gadgets that pull a lot of amps and upsizing your alt further would require replacing major wiring.
1. Draws way less current .. less than half!
2. A lot less noise, like half!
3. EMI is almost non existent.. VERY important for EFI guys
4. 1/3 the weight
5. no voltage/current surges on your system
6. Lasts years longer
Or you can go cheap crap old tech brush fans.. I had the Spals for a while also... compared to the Delta PAG,,, yea, they are crap.
The brushless motor is the heart of the fan. It is constructed using high temp/high strength Neodymium magnets, hybrid ceramic bearings, stainless steel flux ring & multi-stranded "Litz" windings. The motor is very power dense, allowing for smaller construction, while generating high power. The operating life is conservatively rated at 30,000 hours. Please note, a typical brushed motor fan is rated at 2,000 hours.
Brushless DC (BLDC) motors offer several advantages over brushed DC motors. BLDCs are lighter and more efficient than conventional brushed motors, therefore reducing the energy consumption of the vehicle. As a result, Saving Gas! The elimination of brushes in a BLDC significantly increases motor reliability, reduces noise, reduces heat and increases efficiency due to the elimination of friction between the brushes and the commutator. Brushed DC motors have a typical efficiency of 70-75%, while a brushless DC motor can achieve 96% efficiency, a +28% improvement. While a brushed motor operates, sparks are created when the brushes rub against the commutator, this creates a fire hazard and produces EMI. BLDCs generate no sparks and significantly reduce interference emissions allowing for easier compliance with electromagnetic compatibility (EMC) requirements. Most modern vehicles incorporate computer controls in engine management and other general vehicle operations. Reducing electromagnetic interference (EMI) is critical for proper vehicle operation.
The BLDC motor has permanent magnets and flux ring which rotate around a fixed armature or stator, eliminating the problems of connecting current to the moving armature via brushes. The stator consists of a multiphase copper coil windings (U V W in figure 1) on a laminated core, and the rotor consists of permanent magnet segments or a molded ferrite ring that is attached at one end to the motor’s shaft. The stator windings are fed with electric currents controlled in magnitude and sequence (commutated) with pulse width modulation (PWM) to effect rotation of the rotor element just as in a typical brushed motor. Back-electromagnetic force (BEMF) is used for rotor positioning. This eliminates the need for hall sensors chips in the motor to identify the rotors position. These sensors are prone to burning out which limit the reliability of a motor. Since there are no sensors in our motor, the BLDC motor is called "sensor-less". This "commutation" is controlled by the electronic control module (ECM). All brushless motors require an ECM for operation.
Powerful: adjustable from 1,000 CFM to 2,800 CFM
Reliable: +50,000 hours operating life, 10x more than conventional fans
CFD optimized fan blade profile
Ultra-efficient: +20% improvement =
more power, less fuel consumption
Soft Start Technology eliminates power spikes
Easily replaceable control module
Self cooling technology = reliable, long
lasting operation
State-of-the-art tech, two patents awarded*
Amazing post! You're selling me rapidly, but, personally, I have less than ZERO desire to fab up or hunt down a custom shroud solution. Are there any off-the-shelf fan+shroud combos available that seamlessly mount up to the common inexpensive radiators available for our C3s? (If I could get this fan with a built in shroud for say a Champion 3 row, I'll be sold in a heartbeat.)
-I see for $89, you send them a cad drawing or measurements and they'll fab you up a custom shroud; but again, I don't trust myself to do any of these measurements. If they've got a proven shroud for an 79 auto AC vette with a Champion radiator that they'll guarantee fits, that's one thing, but asking someone to provide a 3D cad drawing for a custom shroud is another thing entirely.
Adam
Last edited by NewbVetteGuy; 05-04-2017 at 02:52 PM.
Amazing post! You're selling me rapidly, but, personally, I have less than ZERO desire to fab up or hunt down a custom shroud solution. Are there any off-the-shelf fan+shroud combos available that seamlessly mount up to the common inexpensive radiators available for our C3s? (If I could get this fan with a built in shroud for say a Champion 3 row, I'll be sold in a heartbeat.)
Adam
POST #15
Yes, Delta PAG will make you a custom shroud for a very reasonable price.
There have been SO many threads on this in the past. Ultimately you can get the CFM that you need in single or dual fans, but dual fans with dual relays and redundant wiring get you increased reliability if anything goes wrong, you still have enough cooling to get home without calling a tow truck, AAA, or using your Hagerty tow benefit for the year.
Dual fans pull significantly more amps, from the alternator, though; the single fan option is definitely more efficient if you plan to have a lot of gadgets that pull a lot of amps and upsizing your alt further would require replacing major wiring.
Adam
Hey Adam,
Unless you live in a very heavy traffic area, a failed fan should never stop you getting home. Any time you are moving at more than a crawl the fan is (should be) not required... My fan cycles on and off when stuck in traffic or sitting idling, it never runs while I'm driving above ~20-30mph. Even if it is a heavy traffic area, worst case if it climbs higher than you're comfortable you can just pull over and pop the hood a few minutes until it cools down a bit.
The Delta PAG fans sound great, I'll look at them next time I need one, but the Spals are still (at worst) the best of the rest, they're a very good fan and have much more honest cfm ratings than most of their competitors. FWIW I'm not having any trouble with EMI from mine, and it is controlled by my (Fitech) EFI.
A lot to comment on here, let's start with what Spal actually recommends.
"The design criteria for any automotive application is at least 2000 cfm and 70 percent core coverage."
With that said, we use the Spal dual 11" (2780 cfm) which does have a separation bar, so you can run one without the other. For the record, this is what Be-cool sells too. They just don't call them Spal but they are.
Now I've sold probably 5,000 radiators or more in my lifetime with dual Spals and never once did anyone say it wasn't enough. The reason we do not use a single fan on C3's is because of the coverage criteria. The C3 radiators are rectangles and single fans are round. You can't get 70 percent coverage with a single unless you build a big pan shroud to house it in.
Brush type fans are not dead or old technology. They work and work well. Brushless fans are very nice, albeit a little expensive. IMO Spal make the best one of those too.
05-03-2017, 09:43 PM
Elec. Fan or Fans ... which is better???
