Thanks.....I'm actually thinking about a SPAL brush-less....any good word on them?
Jeff
Video - Horsepower Loss To Fans.....
- Thread starter MrJLR
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Jeff
They are good too, but the Black Magic is specifically for high HP muscle cars, whereas Spal specializes in European car stuff that just "happens" to work ok. I know which one I would want.
Amps x Volts = Watts
1hp = 745.7W
Most cars have an Amp meter...this shouldn't be too hard to ball-park
MopaR&D
Nerd Member
I think they both have their ups and downs, electric fan will always be more efficient even though it technically still draws HP but mechanical is more reliable. I think the point of the video showed that with a mechanical fan it's always tied to engine RPM so when you rev it up it starts drawing way more HP than it needs to cool the engine. OEMs are even using electric fans in pickups nowadays, it's very recent but they've obviously got the reliability nailed down. I like my factory-style clutch fan though because it fits, it works and I already have it 
BTW even new cars that are FR layout like my mom's 300 have an electric cooling fan. The neat thing I noticed is it's 2-speed, normally it's almost silent but when you're sitting idling in hot weather with the A/C cranked up the fan goes on full blast and you can hear it. With our old cars there wasn't really a way to increase airflow through the rad it idle unless the idle speed was kicked up (which also makes more heat) so the fans had to be designed to pull the required air at idle while still not drawing tooo much HP at high RPMs, pretty big trade-off.
BTW even new cars that are FR layout like my mom's 300 have an electric cooling fan. The neat thing I noticed is it's 2-speed, normally it's almost silent but when you're sitting idling in hot weather with the A/C cranked up the fan goes on full blast and you can hear it. With our old cars there wasn't really a way to increase airflow through the rad it idle unless the idle speed was kicked up (which also makes more heat) so the fans had to be designed to pull the required air at idle while still not drawing tooo much HP at high RPMs, pretty big trade-off.
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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What percentage of the time are you driving at 5200? or how about 3900? At 3900 the torque loss of the thermostatic clutch-fan was, IIRC, 8 flbs.
8 x3900/5250 = 6hp. I'll gladly accept that 6 hp loss.
>By 30mph,when ram air begins to take over the cooling duty,I wonder just how hard the fan is really working. I mean it has a 30 mph wind in front of it, and the air-temp through the rad has dropped to maybe 150*. The thermostat on the clutch is probably allowing the clutch to slip at or near maximum-slip.
I think at 30mph the horsepower loss might be closer to zero.For me, In first gear this will be 4089rpm; second will be 2527; and third would be 1839. It doesn't have anything to do with rpm anymore.
>At 60 mph Ram air is operating at full capacity and the fan is being propellered by the 60mph wind coming thru the rad. Any clutched fan is going for a free-ride.I mean stick your arm out the window at 60mph and see what happens!
>I can't say what might be happening at the top-end of the track, but since a good bunch of us are in the low 12s, and it's about 6 or 7 seconds from 60mph to 110ish, If I was a betting man, I'd put money on the fan not even needing to be on there, until the return road.
>So, when is that thermostatic clutch fan really costing power, and how much?
My theory is that the fan only costs horsepower below 30ish mph, and if I was stuck in first gear, it would be 6 big fat horsepower, at 3900, somewhere well below 30 mph.
But guess what; I can spin 325DRs on the primaries, so 6 bigfathorsepower means exactly nothing to me.
That's my theory.
K.i.s.s.
if the engine is running, then the fan is spinning. The faster the engine is running, the faster the fan is spinning. And it's all automatic.
And my 35Amp alternator lasts over 20 years.
Oh yeah;I lost a belt once, in 1971.I was 19 and ignorant.
8 x3900/5250 = 6hp. I'll gladly accept that 6 hp loss.
>By 30mph,when ram air begins to take over the cooling duty,I wonder just how hard the fan is really working. I mean it has a 30 mph wind in front of it, and the air-temp through the rad has dropped to maybe 150*. The thermostat on the clutch is probably allowing the clutch to slip at or near maximum-slip.
I think at 30mph the horsepower loss might be closer to zero.For me, In first gear this will be 4089rpm; second will be 2527; and third would be 1839. It doesn't have anything to do with rpm anymore.
>At 60 mph Ram air is operating at full capacity and the fan is being propellered by the 60mph wind coming thru the rad. Any clutched fan is going for a free-ride.I mean stick your arm out the window at 60mph and see what happens!
>I can't say what might be happening at the top-end of the track, but since a good bunch of us are in the low 12s, and it's about 6 or 7 seconds from 60mph to 110ish, If I was a betting man, I'd put money on the fan not even needing to be on there, until the return road.
>So, when is that thermostatic clutch fan really costing power, and how much?
My theory is that the fan only costs horsepower below 30ish mph, and if I was stuck in first gear, it would be 6 big fat horsepower, at 3900, somewhere well below 30 mph.
But guess what; I can spin 325DRs on the primaries, so 6 bigfathorsepower means exactly nothing to me.
That's my theory.
K.i.s.s.
if the engine is running, then the fan is spinning. The faster the engine is running, the faster the fan is spinning. And it's all automatic.
And my 35Amp alternator lasts over 20 years.
Oh yeah;I lost a belt once, in 1971.I was 19 and ignorant.
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ir3333
Well-Known Member
i did see a test on an alternator and it was around 8 hp.The amount of load and size of the alternator would vary as well.
why didn't they test a standard style flex fan.I have a 70's Mopar flex fan currently on my car
and it is visibly flat a little past 2000 rpm.
why didn't they test a standard style flex fan.I have a 70's Mopar flex fan currently on my car
and it is visibly flat a little past 2000 rpm.
AJ/FormS
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A 100A alternator fully loaded and still putting out 15.2 volts would be 100x 15.2/746= 2 electrical hp
As earlier said if it was 25% efficient then, it would take 2/.25= 8 crank-hp to drive it.
Now that is 100% loaded. Like 3 fans, plus ignition, lights, etc
As earlier said if it was 25% efficient then, it would take 2/.25= 8 crank-hp to drive it.
Now that is 100% loaded. Like 3 fans, plus ignition, lights, etc
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Phily
3XL, loud pipes, loud music, loud weed
How the hell does an alternator cost you horsepower. It doesn't tighten as it gets used more. The closest thing I could think of is maybe you work get as much spark into your plugs. You don't put an bigger alternator to increase hp. You add a bigger alternator when. You add more electric using componentz, you know like my 2000 watt stereo system in my van. I've never noticed any difference in power. A fan doesn't use close to that
And as for the fan shroud losing or making hp. It's obvious science. You have a shroud and a radiator. Where do you get the air? From the other side of the radiator. Made so you suck air through the radiator better cooling you coolant. When you have to pull air through the radiator it causes more restriction on the fan which if belt driven causes more resistance on the motor, which robs hp.
As for a fan or electric fan making power. Well if you already have a belt fan and switch to electric and you get more power I'd say you made more hp. But I wouldn't say it like the fan is causing your hp to be made but freed up. Same idea with a carb. If you can put a bigger one on and you get more hp you are making more, but technically you are freeing it up from resistance as well, because it flows more.
I do t perceive a glass half full or empty. In fact im a contradiction to myself. Beauty is in the eye of the beholder so to speak
You are more Tha. Welcome.e to correct me if I'm wrong.
And as for the fan shroud losing or making hp. It's obvious science. You have a shroud and a radiator. Where do you get the air? From the other side of the radiator. Made so you suck air through the radiator better cooling you coolant. When you have to pull air through the radiator it causes more restriction on the fan which if belt driven causes more resistance on the motor, which robs hp.
As for a fan or electric fan making power. Well if you already have a belt fan and switch to electric and you get more power I'd say you made more hp. But I wouldn't say it like the fan is causing your hp to be made but freed up. Same idea with a carb. If you can put a bigger one on and you get more hp you are making more, but technically you are freeing it up from resistance as well, because it flows more.
I do t perceive a glass half full or empty. In fact im a contradiction to myself. Beauty is in the eye of the beholder so to speak
You are more Tha. Welcome.e to correct me if I'm wrong.
T56MaxTorq
Well-Known Member
I have a underdriven fixed fan and like it but electric fans have their place.
The video is misleading because those fans don't all move the same amount of air. You can't put a huge fixed fan that moves a lot of air on a V8 and compare it to smaller fan that puts out half the cfm and say the big fan sucks. Well no ****, the big fan is doing more work. What did they expect??
The only way to truely test this is with fans that move the same amount of air. I doubt you'll be able to find an electric fan that can move 4000 cfm with less than 50 amps. That's a lot of draw.
There's way too many variables on both ends. Ram air through the radiator lowers the pressure in front of a fixed fan, and that will immediately reduce the work load. Wouldn't an unregulated electric fan with ram air still pull the same amps but spin faster? But electric fans have a lot of fancy controllers as well, so they got that going for them, but block the radiator when they're not on.
The video is misleading because those fans don't all move the same amount of air. You can't put a huge fixed fan that moves a lot of air on a V8 and compare it to smaller fan that puts out half the cfm and say the big fan sucks. Well no ****, the big fan is doing more work. What did they expect??
The only way to truely test this is with fans that move the same amount of air. I doubt you'll be able to find an electric fan that can move 4000 cfm with less than 50 amps. That's a lot of draw.
There's way too many variables on both ends. Ram air through the radiator lowers the pressure in front of a fixed fan, and that will immediately reduce the work load. Wouldn't an unregulated electric fan with ram air still pull the same amps but spin faster? But electric fans have a lot of fancy controllers as well, so they got that going for them, but block the radiator when they're not on.
T56MaxTorq
Well-Known Member
It kind of does tighten as it's used more. It causes you hp because the magnetic field in the alternator must remain "on" longer than before because the demand is more with a bigger electric load. The voltage regulator basically switches the electro magnets in the alternator on and off very quickly. They're on more with more electric load in the vehicle. This magnetic field from the rotor then pushes electrons in the coil of the alternators stator. The stator coil resists the magnets in the rotor as it's being forced through the field. The more resistance, the more the hp loss.
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As an alternator's load is increased, it becomes more difficult for the engine to turn. It puts more load on the engine.
Honestly, this got way out of hand. It seems everyone completely missed my point.
My point was that if you start chuckin everything that costs HP, there wont be much left. Oil pump, rings, bearings.......anything that causes friction is a HP loss.
It was a sorta rhetorical question......more of a joke really.
Honestly, this got way out of hand. It seems everyone completely missed my point.
My point was that if you start chuckin everything that costs HP, there wont be much left. Oil pump, rings, bearings.......anything that causes friction is a HP loss.
It was a sorta rhetorical question......more of a joke really.
whitepunkonnitro
Well-Known Member
Not exactly applicable to the discussion, but this was my solution to fan/water pump drag on the Slant Dart that I recently built.
Drag car, and so weight was more important to me than anything else.
Car has no alternator, so I used the stock W/P pulley, and a belt that I was able to "bicycle chain" over it and the crank pulley.
Loose fit with no idler. It turns one of those power robbing but super light plastic fans.
The trick part, is that I greased the pulleys. This let's the belt slip with nearly zero friction anytime the engine is spun up.
Once it returns to idle, the belt catches up and spins the pulley normally, keeping everything nice and cool.
Drag car, and so weight was more important to me than anything else.
Car has no alternator, so I used the stock W/P pulley, and a belt that I was able to "bicycle chain" over it and the crank pulley.
Loose fit with no idler. It turns one of those power robbing but super light plastic fans.
The trick part, is that I greased the pulleys. This let's the belt slip with nearly zero friction anytime the engine is spun up.
Once it returns to idle, the belt catches up and spins the pulley normally, keeping everything nice and cool.
66jim
Well-Known Member
Mechanical fans cool more when your moving faster electric cool more when driving slower or stopped. Electric fans work! Electric fans thermostat will turn fan off when moving at a decent speed when cooling is not required, mechanical keeps churning even faster just sucking up power.If you go electric get the non electronic type capillary fan thermostat controller, they are bulletproof and cheap. I have used electric fans on all my cars for 20 years and no failures. Keep in
mind good electrical wiring and attention to connections are absolutely vital this is where you will get problems not with the fans themselves.
mind good electrical wiring and attention to connections are absolutely vital this is where you will get problems not with the fans themselves.
One of the guys at work had Fancy BMW. Had an electric fan and water pump, only made to 30,000 miles. Not for me.
And I know a guy that had a stock fan break and destroy his water pump bearing, radiator, shroud, and wiring. One case certainly doesn't make it the rule. And BMWs are notorious for electrical problems.
SOP for that model. High profile rides take high profile maintenance. And he was OK with putting a $500 water pump on every 30,000 miles. The number of mechanical fans, especially OEM, breaking is very small. I've run electric fans for years. They have their pluses, but I'm into bullet proof now. Clutch fans freewheel at speed and OEM flex fans straighten out at a certain speed. Only fixed blade fans have higher drag the faster they turn.
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I wish they did a dyno run with electric fan hook up to an alternator. But thing it don't matter we know an electric takes hp to turn also but we can control a lot of the variables. Since we don't need the fan to run all the time it really only needs to come on at idle and slow moving traffic where a mechanical fan has problems working effectively. And for racing you can always shut the electric fan off completely before the run costing no hp at all. Plus an electronic fan eat the same hp no matter what rpm your engine is at.
As for reliablity you could always caring a mechanical fan in the truck along with other roads side repair parts.
And even the mechanical camp probably could benefit adding a fan to there cooling system for idle and low speed operation.
As for ditching the fan shroud to gain back so hp your also giving up cooling ability especially at idle.
As for reliablity you could always caring a mechanical fan in the truck along with other roads side repair parts.
And even the mechanical camp probably could benefit adding a fan to there cooling system for idle and low speed operation.
As for ditching the fan shroud to gain back so hp your also giving up cooling ability especially at idle.
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Age old deal!
Simple answer is put a bigger engine with x10 power and stop fretting over 5 HP gains with electric or mechanical fans that take 3 pages to discuss. That's what real hot rodding is!
Otherwise stay with the factory designed it. It worked for 50 years just fine.
Simple answer is put a bigger engine with x10 power and stop fretting over 5 HP gains with electric or mechanical fans that take 3 pages to discuss. That's what real hot rodding is!
Otherwise stay with the factory designed it. It worked for 50 years just fine.
famous bob
mopar misfit
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I had an elec 16" fan on my 505" wedge, it would not keep the approx. 700 h.p. cool. Now have a fixed 7 blade, 17" steel factory fan on, no problem. Also have an elec. 15" pusher , set to come on at 200, it hasn`t come on yet. Like some others on here, think u guys are splitting hairs, when it comes to a big engine. I have seen dragracers cut their belts (in a hurry) to win the final round-back in the day.
This was interesting and insightful for what it is. But it is a very simple test.
It shows that fan load can be surprisingly high - which is good info.
The issue with a simple test is that it always raises more questions but this test isn't a research project.
As mentioned the different fans will move different amounts of air with different engine RPMs being another variable. This gets rather complicated very quickly. And we start to get into the even more complex topic of cooling system and engine system interaction.
As for belt driven vs electric fans the belt driven can move A LOT more air at low engine & vehicle speeds ( think of a tractor in a field or the big block Dart during the Woodward cruise) but high air flow at low engine rpm is nice stuck in traffic with the AC on.
I love the brilliantly simple slant six solution by whitepunkonnitro.
And most important it sounds like it works.
It shows that fan load can be surprisingly high - which is good info.
The issue with a simple test is that it always raises more questions but this test isn't a research project.
As mentioned the different fans will move different amounts of air with different engine RPMs being another variable. This gets rather complicated very quickly. And we start to get into the even more complex topic of cooling system and engine system interaction.
As for belt driven vs electric fans the belt driven can move A LOT more air at low engine & vehicle speeds ( think of a tractor in a field or the big block Dart during the Woodward cruise) but high air flow at low engine rpm is nice stuck in traffic with the AC on.
I love the brilliantly simple slant six solution by whitepunkonnitro.
And most important it sounds like it works.
Yeah he's known for lots of things. Stupid not bein one of them.
While 30k miles is an embarrassingly short life, please don't hold up BMW as the ambassador for the durability for any modern car component.
Don't get me wrong, they're gorgeous and often wonderful driving cars...they're also the exact opposite from what probably makes most of us love A-Body Mopars; rugged, elegantly simple, reliable, lovable, humble cars (with the potential to be a firebreathing monster, of course ;) ) .
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No, I am not a BMW fan, no pun intended, nor a detractor. My only point is, a lot of high tech or race components, are not the best or longest lasting in "street" use.
I agree with your point but I don't like this example. Electric motor driven fans are not what I worry about. They can fail like anything else but more often than not, they will outlast the car and save horsepower in the process.
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