radiator and fan question

[rurouni20xx]

some engineering i dont agree w/ (plastic cam gears in lawn mowers) and most i do agree w/, from a mechanical fan standpoint the fan area being larger and blowing at speeds up to wot (5500-6000 rpm in this case) far exceeds 2000 rpm and a smaller fan size. the dif here is the number of blades and blade size, smaller efans have more smaller blades that generate a fair amount of air at lower speeds. a mechanical fan having a few less blades but spinning faster and having more blade area generates more airflow overall. the only good thing about an efan is to replace the mechanical fan where room doesnt allow for one or to supplement a mechanical fan by giving the mechanical fan more air to blow, hence a two stage fan arrangement. the reason i was asking about the efan to begin w/ was for clearance issues, not to replace it cuz it cools better, which it does not. sure it drags on the crank some but not as much as you would think, once the fan picks up speed the centrifugal force makes it drag less overall. during the speed pickup it drags some, but not nearly as much as other components such as a/c and power steering. efans are better for front wheel drive cars and low area designs, not full replacements. i was worried about a low area design, but now that ive looked at the area that im working w/ im not worried about space anymore, hence the full efan replacement idea is out. and the stupid water pump eliminators/electric water pumps, sorry not going to risk my engine on an electric motor failure, and they sound like shit for the lamen.

 

[99RangerBoss]

efan

the other apprentice at my work has a twin turbo chevette with a franken motor a block from a v-6 camero and heads from a 3.4 alero hes pushing 450 hp and uses a rad from a 4 liter ranger and a efan and has no problems
http://www.youtube.com/watch?v=xcNMqABi1YE before stroking motor
http://www.youtube.com/watch?v=ovVvGuQDYos after stroking motor 3.5L
he drives it in summer a lot

 

[Tee Rev]

OMG!!!

You're not going to try and tell me you have an engineering degree are you!!

This just keeps getting better!! You're fresh out of school aren't you!

I'll be nice & help you out a little!

You might want to take into consideration that not everyone drives a rock crawler, or tows 10,000lbs. In these cases it's probably no more efficient to run an electric fan as it could see close to 100% duty cycle. I'm not saying that you can't, I'm just saying that not efficient.

Now consider a street driven passenger vehicle that spends most of its time moving at a rate of speed that allows far more CFM of air to pass through the radiator than either a mechanical or electric fan can pull. In this case, both fans are effectively free wheeling. All the calculations in the world aren't going to make one more efficient than the other, as neither can overcome the amount of air being passed over the radiator at speed.

How about this, since you say you are an engineer, how many CFM of air is passing through a 24 x 18" radiator at 15 mph? & how does that compare to the CFM of air being pulled by a mechanical fan @ 2000 rpm? How about an electric? Hmmm ... what's that? Already more than either can pull.

You know, there might just be a reason that automakers use e-fans in passenger vehicles.


You sir, do not have an engineering degree. You may have taken some simple engineering in college although I strongly doubt it. And you certainly haven't learned to apply simple logic.

Go back to school and listen ...... you might learn something!

 

[rurouni20xx]

no degree other than outdoor power equipment technology and silver certified yamaha technician, one of two in my state. just a lil pointer here, watch who you dummy down to, im simply stating facts, and im not building a rock crawler. im building a 300+ hp motor for street strip use, not cruising on 20s at 15 mph in the hood w/ my 15s blasting either. an 18" fan at 15 mph or in other words 1500 rpm is pulling as much air as a 16 inch efan at the full capacity of 2000 rpm. beyond that its pulling much more air, and i need this air to cool down a turbocharged 3.3 stroker boosted to 15psi for approx 300 hp, and i may even occasionally go the full 20 psi the internals are rated and have a go at an ls1 corvette just to see how shell do. keep your efan, im sticking to mechanical.

 

[THE H.P FREAK]

HI!... JFYI I was running 430H.P daily driven F-150, with twin 16 electric fans. The secondary fan was just there in case I needed it. It never got used. Ran the truck like that for 10 years. One of those fan has been on my 07 Ranger now for a year , no issues. I also ran a MEZIERE electric water pump on my F-150 for 3 years. Never had a problem.

Currently building a built 5.4 with a t-88 turbo that will be making 800RWH.P. Still will be running twin electric fans and a electric water pump. Others with the same combo have no issues.

 

[shadetree]

no degree other than outdoor power equipment technology and silver certified yamaha technician, one of two in my state. just a lil pointer here, watch who you dummy down to, im simply stating facts, and im not building a rock crawler. im building a 300+ hp motor for street strip use, not cruising on 20s at 15 mph in the hood w/ my 15s blasting either. an 18" fan at 15 mph or in other words 1500 rpm is pulling as much air as a 16 inch efan at the full capacity of 2000 rpm. beyond that its pulling much more air, and i need this air to cool down a turbocharged 3.3 stroker boosted to 15psi for approx 300 hp, and i may even occasionally go the full 20 psi the internals are rated and have a go at an ls1 corvette just to see how shell do. keep your efan, im sticking to mechanical.

rurouni, I think his post was directed to Bob Ayers, not you. Ayers supposedly has an Electronic Engineering degree, not a Mechanical Engineering degree?shady

 

[betomonroy]

The only difference that really matters between an efan and a mech fan is called constant air flow. Now in case Dee dee dee dosn't understand with his PHD or Masters or GED this is what makes the difference. And growing up in a very hot climate I can tell You that efan rules when it comes to city driving because of the constant air flow. And are useless at Highway speeds because of THU!!! Air speed. You can drive your car on the Freeway with an efan turned off. But when you really need High Flow mech fans rule. If You want to put it into perspective mileage and hp do not should interest You if You really want to keep things cool.
So efan or mech fan is up to each one his or her own choice.
There... I said it.
And if some Dee dee dee doesn't like it... IDC an STFU

 

[Bob Ayers]

OMG!!!

You're not going to try and tell me you have an engineering degree are you!!

This just keeps getting better!! You're fresh out of school aren't you!

I'll be nice & help you out a little!

You might want to take into consideration that not everyone drives a rock crawler, or tows 10,000lbs. In these cases it's probably no more efficient to run an electric fan as it could see close to 100% duty cycle. I'm not saying that you can't, I'm just saying that not efficient.

Now consider a street driven passenger vehicle that spends most of its time moving at a rate of speed that allows far more CFM of air to pass through the radiator than either a mechanical or electric fan can pull. In this case, both fans are effectively free wheeling. All the calculations in the world aren't going to make one more efficient than the other, as neither can overcome the amount of air being passed over the radiator at speed.

How about this, since you say you are an engineer, how many CFM of air is passing through a 24 x 18" radiator at 15 mph? & how does that compare to the CFM of air being pulled by a mechanical fan @ 2000 rpm? How about an electric? Hmmm ... what's that? Already more than either can pull.

You know, there might just be a reason that automakers use e-fans in passenger vehicles.


You sir, do not have an engineering degree. You may have taken some simple engineering in college although I strongly doubt it. And you certainly haven't learned to apply simple logic.

Go back to school and listen ...... you might learn something!

I think I see a trend here.....the intelligence level of Canadians!!!!

 

[thegoat4]

The downside of running an e-fan (beyond the lowered cooling capacity) is that the fan can completely shut off at times. If you are at a stop, and the fan is off, that turbocharger housing is still dumping a lot of heat into the engine compartment.

A mechanical fan is always turning with the engine and will always cause some movement of air through the engine compartment. That will keep everything cooler and make the stuff near the turbocharger last longer.

 

[reitzranger]

if you want a efan get one out of a Mark viii. They are 2 speed, 18" and push a ton of air.

 

[THE H.P FREAK]

I think I see a trend here.....the intelligence level of Canadians!!!!

HI!... I do to. That were smarter.............

 

[rurouni20xx]

and you dont run 98 degree temperatures at 100 percent humidity in canada like i do in louisiana do you? i need the constant airflow a mechanical fan provides to keep my turbo cool at the non synchronized redlights we have around here. i dont care what kind of phd mba ba somebody has its all bs to me, real world experience has taught me otherwise. the question was what i stated b4, do i need to run an efan for clearance, the answer is no. this should settle everything.

 

[THE H.P FREAK]

and you dont run 98 degree temperatures at 100 percent humidity in canada like i do in louisiana do you? i need the constant airflow a mechanical fan provides to keep my turbo cool at the non synchronized redlights we have around here. i dont care what kind of phd mba ba somebody has its all bs to me, real world experience has taught me otherwise. the question was what i stated b4, do i need to run an efan for clearance, the answer is no. this should settle everything.

HI!... Don't let the "CANADA" thing fool ya. We get hot as hell here in the summer. 90-100% humidity for about 4 months of the year and temps in the 90's and 100's also. No synchronized lights here in my town either and bumper to bumper traffic is very common. My electric fans far outperform my previous clutch fans in this element.

 

[04 EDGE]

I can figure out how an e-fan works without throwing money away on one

well mine works just fine so yeah.

bob, your all your wisdom please teach us the differences between the two fans.

so how is a viscus belt driven fan better then an electric fan.

i'll go make some popcorn

 

[Bob Ayers]

well mine works just fine so yeah.

bob, your all your wisdom please teach us the differences between the two fans.

so how is a viscus belt driven fan better then an electric fan.

i'll go make some popcorn

One more time for you slow learners:

1) Mechanical fan/clutch has much higher cooling capacity than e-fans

2) Mechanical fan/clutch has much higher reliability than e-fans

3) E-fans loose efficiency due to mechanical to electric back to mechanical energy conversions


Another opinion about e-fans:

Cooling Capacity:

By far, the most common misconception is that the electric fan cools better then the stock. People see the high CFM numbers in the catalogues (for example, the Black Magic is advertised as pulling 2,800 CFM, and the Perma Cool "finger chopper" is advertised at 2,950 CFM) and are impressed. The truth is that no one actually knows the CFM rating of the stock fan. It has simply never been measured by anyone in the aftermarket and listed. All we do know is that it is rated at "a lot", more times than not it will exceed 4000 CFM. And to be honest, who cares how much air the stock fan moves? It is more then adaquate as long as it's clutch and the rest of the cooling system is in good shape. The steeply raked blades of the stock fan move quite a lot of air, even if it turns slower then an aftermarket electric unit. Experience has shown that when in good shape, the stock fan is even easily capable of handling a 400HP engine. How much power do you make?


Efficiency:

Of course, you're not necessarily after better cooling. You've seen those TV commercials or catalogue ads that promise "Up to 17 free HP!" by converting to an electric fan. Well, that's simply not true. There will be a horsepower gain for sure, on the order of 0.5 - 5HP, with 17 H.P. reserved for big V-8s using 40 lb fans at 6000 rpms. But remember that the electric power to run the fan must come from somewhere, and that somewhere is the alternator. Electric fans draw quite a lot of current. Most pull surges of 35A or more to start up, then run at 8A-10A. This puts extra load on the alternator. Ever pedaled a bicycle with a generator powered light? If so, then you will know that as the electrical load on a generator/alternator increases, the generator/alternator becomes harder to turn. Suddenly, all that "free" HP you just freed up is once again being used. This time, though, it is being used to turn the alternator. There is also an inefficiency in the whole system. We are converting mechanical energy, to electrical energy, to mechanical again to run the fan. This very inefficient, much less then just driving the fan directly via the mechanical energy of the rotating shaft


Reliability:

Lastly, there is the question of reliability. The stock clutch fan can have two failure modes: the clutch will fail, or the fan will physically break. The electric fan introduces many more failure points: fuse, all wiring connections, physical failure of the fan, failure of the motor, failure of the thermostat