Actual HP Gains / Elec. Fan / Pulleys

93gtmustang · Jul 26, 2007

What is the actual horse power gain from underdrive pulleys and an electric fan.?
I don't know if anyone has done an actual before and after dyno test.
I've seen advertisements stating 10-15 hp.

Turkey Sammich · Jul 26, 2007

I would never trust the ad's. There are far to many factors involved.

I would say 6-10 would be more realistic.

4G-KDMP · Jul 26, 2007

as stated; never trust the ad's, there are far to many factors involved.
however imo i'd guess 4-6 hp gain.

ninety15.0 · Jul 27, 2007

I would actually guess a little more than that. If we are talking rwhp i would guess probably 8-12 after installing both the e-fan and the pullies.

jrichker · Jul 27, 2007

The electic fan uses approximately 1/2 HP of electrical energy.

Fan electrical requirements: Figure 14 volts x 30 amps = 420 watts. It takes 746 watts to make 1 HP, so 420/746 = .56 HP

By the time you figure losses from generating the electricty for the fan, the fan uses about 5/8 HP drawn from the crankshaft. Compare that to whatever numbers you have for the crankshaft HP required to drive a mechanical fan, and you have a nice boost in HP.

Sicarius428 · Jul 27, 2007

To the rear wheels probably 5ish HP gain. Nothing you can really feel but with the E fan, your motor will rev up faster. The throttle was a lot snappier than with the mechanical fan. Also consider that your electrical and cooling system is a little more strained to keep up after you do the pullies and efan. That alone will rob some power additional power somewhere to keep things working.
Kevin

85_SS_302_Coupe · Jul 27, 2007

I dropped 2 tenths with an AC delete and eFan.

dtlionsfan · Jul 27, 2007

I would bet an easy 15 to the wheels.

stykthyn · Jul 27, 2007

wow, these answers are pinging all over the chart

85_SS_302_Coupe · Jul 27, 2007

stykthyn said:
wow, these answers are pinging all over the chart

Yeah that's why i never bothered to guess on HP numbers....the butt-dyno is never that accurate

my best ET when i first got my coupe with the motor bone stock was a 14.7x, and just by gutting the AC and smog and going to a short belt and switching to an eFan, i dropped to 14.5x. That's pretty good if you ask me considering it barely cost anything. It was also a consistent gain, not just a one time fluke. I could've ran brackets on a 14.5 dial and made a killing.

Fett · Jul 27, 2007

It's funny, I never understood the "I could feel the power" assessments I read. I have never done any one thing that made me feel any power, even though trips to the track showed improvement.

I know when I put my e-fan on, I didn't feel ANY difference in anything. Throttle felt the same, power felt the same, nothing changed....yet the track showed otherwise.

I don't think you can feel anything under 10hp, and I doubt you can feel anything under 15hp.

85_SS_302_Coupe · Jul 27, 2007

The only thing i've felt is that the car is just generally more enthusiastic with each mod....that is the things i've done to the engine itself.

When i got headers and full exhaust, it would rev so much freer and smoother.

When i got a new intake and carb...wow...that was like night and day. Much more responsive throttle and really did pull harder all throughout the RPMs.

All things combined i've shafed a half second off my ET and i'm still destroying the tires in 1st through 3rd and can't cut better than a 2.0 60' to save my life.

DMAN302 · Jul 27, 2007

I have dyno sheets from different days....only changes were brand new (very tight) clutch fan to a taurus fan/Dcc and change in SCT program to a '94 octane' program that increased timing aprox 2 degrees throught out the curve. She leaned out from 12.5 to around 13 with the timing change so you can likely associate some of the gains there. Increase was 291/316 to 315/344...repeated the last numbers on another day so they were and are accurate. No change in power before 3000 rpm and increase from then gradually to the largest gain at max rpm...as you would expect. How much to attribute to the fan or A/F/timing....can't say. What I can say is I didn't 'notice' much difference at all on the street even with the substantial gain. I will say the better condition of the fan..the more HP it will use, older fans likey will show less gain due to clutch wear IMO.

patrickmx2 · Jul 27, 2007

I've seen consistent gains of several cars with electric fan conversions pick up 2 tenths in the 1/8th mile tracks I frequent. Temps and conditions were the same. Pulleys not so much to any difference at all as one change but what is odd when combined with a fan from stock I've seen 3 tenths total and about 1mph gain.

stang&2Birds · Jul 28, 2007

jrichker said:
The electic fan uses approximately 1/2 HP of electrical energy.

Fan electrical requirements: Figure 14 volts x 30 amps = 420 watts. It takes 746 watts to make 1 HP, so 420/746 = .56 HP

By the time you figure losses from generating the electricty for the fan, the fan uses about 5/8 HP drawn from the crankshaft. Compare that to whatever numbers you have for the crankshaft HP required to drive a mechanical fan, and you have a nice boost in HP.

I disagree.
Fact: It takes "X" amount of energy to move "Y" CFMs.
Fact: A *Fixed* fan has NO HP loss moving "Y" CFMs of air.
Fact: An electric fan has energy loss in many places: Mechanical to Magnetic energy in the alternator; loss in the AC to DC conversion ; loss of the voltage regulation; loss of the inefficient fan motor, and so on.

I think I said it nicely on the corral.. I'll try to summarize:
o Dynos for fan changes are BS!

o For city back to back driving where you never go over ~10-20mph, a *good thermal* clutch fan is best.

o The Stang came with a good OEM thermal clutch fan. Not some POS speed-only clutch or some POS thermal clutch.

o For a fan of equal CFM ability to the good OEM thermalclutch fan, you'll see maybe ~5HP gain above ~3K-4K rpms. Back in the 90's there were a few "real" dynos done on the OEM thermal clutch fan vs an "equal" electric fan.

o A PWM controlled electric fan is the best. Next is the 2-speed. The single speed fans are horribly inefficient at idle compared to a *good thermal clutch* fan.

o At highway speeds, electric fans rule! No HP loss. A thermal clutch fan will take ~3->7 HP depending on rpm.

o In most cases, doing a dyno with a fan is a [/b]joke[/b]! It has very little to do with the real world! Especially on a car with a very tight engine bay like the stang! At ~55mph, about ?70%? of the HP that the car used is used to overcome air resistance. Now, in a tight engine bay, there is a LOT of air resistance between the fan and the engine. Opening up the hood, blowing AC cooled air into the radiator, and so on has nothing to do with the real world!

o For the track, you want a fan that you can shut off just before the run and that you can keep on just before the run. That way, you have the coolest engine possible with no HP loss at the run. The decrease in engine temp alone for an electric fan is worth it for a track car. The electric fan will cool at lot even at idle. But, the clutch fans don't.

Like I said, there are many many factors that going converting between mechanical energy and electrical energy in real life. At work, I have to worry about even *very* small percentages.

So, in general, a 2-speed fan is pretty good. A PWM based control for an electric fan is the best since it can control the *required* amount of air flow the most accurate (thermal clutches are okay, but not very accurate).

For bumper to bumper city driving, go with a thermal clutch. It'll last a long time, you can have a more aggressive pitch on the blades, and there's no battery draw.

I said my piece. Yea, many other will disagree. That's fine. I know what I do for a living and I know what it's like having to deal with real world conversion of energy.

Opps, want to add. For a Stang, that has poor engine bay air flow and restricted outside air openings, you want an electric fan because it can move it's max amount of air flow even at idle. The thermal clutch fan is limited by the engine speed. So, for cars that tend to overheat, even though a thermal clutch fan may move more CFM at 3K+ engine rpm, for cars that get hot at idle, you want something like an MKVIII fan. At idle, the MKVII fan will kick the clutch fan's *ss in moving air. But, it'll also take more HP. Sorry, you can *not* get "energy for free". Once again, for a big fan like the MKVII, you want either a PWM controller or a 2 speed controller. In general, you shouldn't need the full fan speed at idle.

jrichker · Jul 28, 2007

stang&2Birds said:
I disagree.
Fact: It takes "X" amount of energy to move "Y" CFMs.
Fact: A *Fixed* fan has NO HP loss moving "Y" CFMs of air.
Fact: An electric fan has energy loss in many places: Mechanical to Magnetic energy in the alternator; loss in the AC to DC conversion ; loss of the voltage regulation; loss of the inefficient fan motor, and so on.

I think I said it nicely on the corral.. I'll try to summarize:
o Dynos for fan changes are BS!

o For city back to back driving where you never go over ~10-20mph, a *good thermal* clutch fan is best.

o The Stang came with a good OEM thermal clutch fan. Not some POS speed-only clutch or some POS thermal clutch.

o For a fan of equal CFM ability to the good OEM thermalclutch fan, you'll see maybe ~5HP gain above ~3K-4K rpms. Back in the 90's there were a few "real" dynos done on the OEM thermal clutch fan vs an "equal" electric fan.

o A PWM controlled electric fan is the best. Next is the 2-speed. The single speed fans are horribly inefficient at idle compared to a *good thermal clutch* fan.

o At highway speeds, electric fans rule! No HP loss. A thermal clutch fan will take ~3->7 HP depending on rpm.

o In most cases, doing a dyno with a fan is a [/b]joke[/b]! It has very little to do with the real world! Especially on a car with a very tight engine bay like the stang! At ~55mph, about ?70%? of the HP that the car used is used to overcome air resistance. Now, in a tight engine bay, there is a LOT of air resistance between the fan and the engine. Opening up the hood, blowing AC cooled air into the radiator, and so on has nothing to do with the real world!

o For the track, you want a fan that you can shut off just before the run and that you can keep on just before the run. That way, you have the coolest engine possible with no HP loss at the run. The decrease in engine temp alone for an electric fan is worth it for a track car. The electric fan will cool at lot even at idle. But, the clutch fans don't.

Like I said, there are many many factors that going converting between mechanical energy and electrical energy in real life. At work, I have to worry about even *very* small percentages.

So, in general, a 2-speed fan is pretty good. A PWM based control for an electric fan is the best since it can control the *required* amount of air flow the most accurate (thermal clutches are okay, but not very accurate).

For bumper to bumper city driving, go with a thermal clutch. It'll last a long time, you can have a more aggressive pitch on the blades, and there's no battery draw.

I said my piece. Yea, many other will disagree. That's fine. I know what I do for a living and I know what it's like having to deal with real world conversion of energy.

Opps, want to add. For a Stang, that has poor engine bay air flow and restricted outside air openings, you want an electric fan because it can move it's max amount of air flow even at idle. The thermal clutch fan is limited by the engine speed. So, for cars that tend to overheat, even though a thermal clutch fan may move more CFM at 3K+ engine rpm, for cars that get hot at idle, you want something like an MKVIII fan. At idle, the MKVII fan will kick the clutch fan's *ss in moving air. But, it'll also take more HP. Sorry, you can *not* get "energy for free". Once again, for a big fan like the MKVII, you want either a PWM controller or a 2 speed controller. In general, you shouldn't need the full fan speed at idle.

Opinions aside, what’s wrong with the math?
Volts times Current (amps) equals watts.
It takes 746 watts to make 1 HP (horsepower).

The common automotive fan circuit is fused for 30 amps. The standard automotive fuse will carry 125% of rated capacity for an extended time before it blows. This extra capacity decreases as the ambient air temp increases above 25 degrees C. Most fuses are located under the hood where the temp exceeds 50 degrees C. So, for simplicity’s sake, the fan draws 30 amps.

Multiplying it out: 14 volts times 30 amps = 420 watts. 420 watts divided by 746 watts (1 Hp) = .56 Hp worth of electrical energy drawn from the electrical system. Figure in an 85% efficiency factor converting mechanical power into electrical power, you end up with .66 Hp worth power drawn from the crankshaft. Even with a 50% efficiency factor (I doubt that it is that low), it works out to 1 1/8 Hp drawn from the crankshaft.

The only debatable point is the parasitic drag of the stock fan. Since I didn't have any reliable figures, I did not speak to that issue. However, I have heard figures ranging from 4-12 Hp at full throttle. I would like to hear from someone what the typical parasitic drag is for reliable comparison, but that is what this thread is all about.

The good news is that no matter what you use for drag and efficiency figures, you get a minimum of 3 Hp from an electric fan swap. The bad news is that 3 Hp will probably get lost in the repeatability factor on a series of dyno runs.

Shakerhood · Jul 28, 2007

Sicarius428 said:
To the rear wheels probably 5ish HP gain. Nothing you can really feel but with the E fan, your motor will rev up faster. The throttle was a lot snappier than with the mechanical fan. Also consider that your electrical and cooling system is a little more strained to keep up after you do the pullies and efan. That alone will rob some power additional power somewhere to keep things working.
Kevin

The 3G Conversion should be done with the E Fan so that the Electrical System is not strained, I think the Stock Alt strains to keep a Stock Stang going!

85_SS_302_Coupe · Jul 28, 2007

Shakerhood said:
The 3G Conversion should be done with the E Fan so that the Electrical System is not strained, I think the Stock Alt strains to keep a Stock Stang going!

It does....the stock alt is a slouch in stock form, let alone when you add an MSD ignition and stereo and efan.

dtlionsfan · Jul 29, 2007

Sorry,slide rules don't always win."real world" to me is doing a mod and testing it at the dragstrip and this mod is good for at least 15 to the wheels.minimum.

85_SS_302_Coupe · Jul 29, 2007

dtlionsfan said:
Sorry,slide rules don't always win."real world" to me is doing a mod and testing it at the dragstrip and this mod is good for at least 15 to the wheels.minimum.

You contradicted yourself a bit....unless your drag strip has a dyno JFWY

Actual HP Gains / Elec. Fan / Pulleys

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