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yes but...

it wouldn't be worth the effort.....

I mean if you want to run the risk of over-heating to gain 1 or maybe 2 HP go for it..


but if your motor is cold, your fan clutch pretty much alows the fan to slip so much that it doesn't draw very much power...
 

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Re: yes but...

People have had mixed results. Many say that it helps at very high rpm. I haven't done mine yet but I am putting in the wiring for an electric fan into the main harness.

If you want to see if it makes a difference, try it. Pull the fan off and drive around. Just don't go to far from home and watch out for the car overheating. You will definitely need to put in an electric fan if you remove the stock one.
 

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No free lunch

I wouldn't recommend it. Most late model vehicles have them becuase they have to (the engine is sitting sideways). But if you removed the mechanical fan and gained, lets say, 1 hp. And then put on an electric fan that draws 20 amps at 14 volts. 20 x 14 = 280 watts, and lets say the alternator is 75% efficient then 280 / .75 = 373 watts = about 1/2 hp. So you may gain 1/2 hp for a couple hours work and $100+. Doesn't seem like that good of a deal to me.

Just my $.02
 

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Not only do you gain power but it increases the ability for your car to rev quicker,and you can control when you want the fan to come on. Not to mention over time the gas U will save and what about when the stock fan clutch goes bad on you at 70 mph. on the freeway and desides to journey through your radiator? How much will that cost you without counting the time your on the side of the road waiting 4 somone? Then theres the xtra wear and tear on the water pump because its supporting all the weight of that heavy fan & clutch,besides, your car does not even use the fan to cool the rad. as soon as you hit 35 mph,it will rely on outside
air coming from you driving through it,however you might want to switch it on if tour pulling a big hill in the heat of summer.



P.S. most of these guys are only guessing as to what really works and what doesnt,ask them if they have ever tried it and you most likely wont get a responce, that what happens to me quit a bit when I ask for real proof or ? ther info.
 

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Doesn't 350z have fan clutch?

From the pics I've seen of the 350z engine it has a fan clutch which makes you wonder if it really did increase HP why wouldn't they just go with an electric fan? You might want to try it for two different reasons though which are reducing engine noise and eliminating the chance of a seized clutch taking out your radiator. I owned two 76's when I was in college and the fan clutches seized on both cars driving down the interstate taking out my shroud and radiator.
 

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Re: Doesn't 350z have fan clutch?

Okay, I have done this on my car. I live in Augusta Ga. The ONLY time I have to turn the fan on is if the car is stopped for more than a couple of minutes. Most of the time I don't even need to turn it on for traffic lights, even in the summer. I didn't even bother to install a thermo switch, I just flip a toggle when I need it. I did notice a slight increase in my motor's willingness to rev. How much hp I gained is anyones guess but it feels better now.
 

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Re: No horsepower gain

There is no horsepower gain from removing the stock fan, adding a lightened flywheel, etc. The engine does not use more fuel/air because you've reduced reciprocating mass, so the engine cannot be making any more horsepower/torque at any specific rpm.

What reducing reciprocating mass does is make the engine rev faster so you get the horsepower you have sooner, thus increasing acceleration. I know its kind of nit-picky, but its the truth. Remember, acceleration is a factor of horsepower AND weight (mass). Reducing mass does not give you more horsepower but it does give you better acceleration.

- John
 

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Re: No horsepower gain

in all reality,
Facts.
it takes power to move a fan, whether on engine or an electric motor.( how much depends on speed , blade pitch,diameter of blades, and to nth degree the density of the air it is moving)
a viscous coupling i.e. fan clutch is very very inefficient hence the cooling fins on the clutch to dissipate wasted energy that converts to heat.
less rotating mass means more usable torque.
Reality
1 an electric fan with a thermoswitch will not run much unless the vehicle is sitting still; ambient air moving at 10-15mph in relation to the radiator will cool a stock engine very well.
2 no crank driven fan will provide previously wasted power from 10 to 25 horsepower depends on the fan removed and inefficiency of fan clutch (see fact above)
3 it will also free up usable torque due to the decreased rotational mass

very simply a fan needs power to rotate.
do I let the fan have the power
or my wheels.

an electric fan WILL (always)
1 provide a little more power
2 provide a little more mpg
3 not eat your radiator
I have done 10 to 15 crank-to-electric fan conversions on every one in DFW area on everything from z's to pickups ALL loved it. the only problem was that if you dont have the setup right the A/C does not blow real cold when at a stop light due to lack of air movement across the core.
btw also keep entire driveline lubricated properly for best mileage
any questions?
 

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Re: No horsepower gain

It's good to hear from someone in the DFW area. I have both an electric fan and the stock fan on my 73Z, and cannot run my AC when the temp gets over 100, even at highway speeds. Am I expecting too much? Or should I be able to find a way to keep it cool in August?

Do you work at a repair shop? If so, please contact me. I've been looking for a place to get my Z worked on since it quit being fun for me to work on them myself. I guess I really am getting old.

Dave at [email protected]
 

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but john

the fan DOES to work.. it pushes air.... it's more than just it's inertia.....

and depending on the condition of the clutch.. it can do ALOT of work.. most of the time alot of unnecesary work......
 

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Re: No buts...

The confusion lies in how torque and horsepower are measured. Horsepower is a derivative of torque based on a specific rpm that the torque is produced. That rpm is a specific, steady state rpm.

300 ft. lbs of torque at 3,000 rpm will be the same number regardless of the rotational mass (assuming the engine can acclerate that mass to 3,000 rpm). Engine dynos add dynamic load (force) to hold an engine, at full throttle, at the specific rpm being measured. The engine has been completely loaded down so it cannot accelerate past 3,000 rpm at full throttle. Increasing the rotational mass by the weight or intertia of a fan or a lightened flywheel does not affect this measurement in a measurable way because we are holding the engine at a steady state rpm, not accelerating it.

What reducing reciprocating mass does (even by small amounts) is allow that engine to get to 3,000 rpm quicker. So, we can deduce that reducing reciprocating mass increases the accelerative capabilites of an engine. But, the engine is still producing 300 ft. lbs. of torque at 3,000 rpm.

I'm not arguing against replacing the fan, I'm just arguing that you do not gain any horsepower by replacing the fan. This is a very common misconception. The engine WILL rev faster without that stock fan and that can lead to quicker acceleration.

Do you guys understand?

- John
 

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Re: No horsepower gain

> it takes power to move a fan, whether on engine or an electric motor.

It tales power to ACCELERATE a fan but it takes very little power to keep it running. Ever notice why the amp rating for electric motors is so high for startup? The pwer needed to keep the stock fan turning at 3,000 rpm is not measurable.

> less rotating mass means more usable torque

Nope. Putting a lightened flywheel on an engine does not give you higher measurable torque numbers on an engine dyno. Been there and seen that dozens of times.

My BSP prepared L6 engine produced IDENTICAL torque numbers throughout the measured rpm range (2,000 to 7,000 rpm) with a stock flywheel and my current 10 lb. Tilton aluminum flywheel on a Clayton Engine Dyno. On a Dyno Jet chassis dyno we did see a 12 horserpower increase from the same lightened flywheel because of a reduction in reciprocating mass. The chassis dyno reported that as an increased ability of the car to accelerate and converted that into a horsepower number. But the engine itself, as proven via previous tests, is not making any more torque!

FYI... we also got a 25 horsepower increase on the chassis dyno by switching to super light racing wheels and tires on one run, but the dyno operator corrected for that immediately.

- John
 

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Re: Oops!

> and to nth degree the density of the air it is moving

I was so focused on the reciprocating mass aspect of the discussion that I forget this "minor" thing about a fan - its performing work moving a fluid (air). Doh!

Sorry...

Taking that bit of work off the engine will let you see some measurable increase in torque (and horsepower). I tend to work these things out given enough time.

- John
 

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Re: Oops too.

You're absolutely right! Sometimes I should just read and think instead of read and type.

- John
 

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Re: No horsepower gain

Try putting a smaller electric fan (10") as a pusher in front of the condensor. Tie it to a relay on your AC compressor so that it turns on when the AC compressor clutch engages. Solved my AC/Elec fan issues. I'm also in the DFW area.
 
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