Here is some Dyno proof that electric fans increase your power for any non believers out there.
How It Was Tested:
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The SR20DET in Carter's 240Z was factory-equipped with a belt-driven fan. To establish how much power we could gain by switching its OE fan to dual Mishimoto electrics, we first strapped it down to G-Dimension's Dynojet with the belt-driven fan in place to establish baseline power, then re-tested once again with the Mishimoto units installed.
What It Delivered:
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Turbo cars with aftermarket EMSs like Carter's can be a bit finicky. All runs conducted at each stage varied a bit from one another, but upon averaging the results, we saw a small, clear-cut 2.5 whp and a 3.1lb-ft of torque gain by switching to the electric fans
A gain of 2.5hp on a 280ish hp car, hmm less than 1% difference. That could be due to almost anything else besides the fans.
It also doesn't explain why the green trace (which I assume is the one with the belt driven fan) makes more power and torque between 2200rpm and 3700rpm.
A gain due to reducing driven fan losses would be a gain across the entire rev range.
They also don't say if the electric fans were running or not during the power run with the electric fans running. (this would make a difference to the alternator load).
I'm not saying electric fans don't increase power, just that that test above is not conclusive enough for me as a mechanical engineer. Yet so many people seem to take things like this printed in magazines as gospel.
In fact I'm switching to electric fans, the space gain being my biggest factor in my choice. Another advantage is that electric fans do not have to run all the time, only when the vehicle speed is slow and the cooling is less.
I love arguing with Engineers around site, Yep 2 whp gain is nothing but wait it is a gain and will give you a small edge over the competitor next to you
The dyno chart is there unless you can supply another that prove otherwise they have proof,anyway I take everything with a pinch of salt and a tequila shot including theory
Problem with dyno readings back to back is the number of variables. Thing like oil temps, air temps, water temp, humidity, atmospheric pressure, etc etc etc. Non of these were considered and I am willing to bet anyone of these could make a bigger difference that the fans did and non were the same on the 2 tests...
The experiment was too crude with no control. When someone does this kind of test in a controlled environment then I will pay attention to the results.
DriftZ: "I swear if a CA18 beats my SR im getting a RB!"
The Import tuner guys are very methodical normally doing three runs sometimes more but I am sure some variables cant be controlled and the power gains can be explained away but like I said there’s theory then there’s real life proof , I have to admit around site sometimes the theory doesn’t go as planned and things need to be taken back to the drawing board
I wouldnt change my fan over to electric for the power I will gain but more for improved cooling and the fact the 2 electrics fans are prob cheaper than a new viscous.
DriftZ: "I swear if a CA18 beats my SR im getting a RB!"
Take the same W to make 2 of the same fans run the same m4 p/s weather mechanical or electrically driven,
one small pro is your removing rotating mass when going to electric so you should gain a SLIGHT amount of power even with the fan running should the M4 p/s be the same and both share same efficiency (love to see someone explain how to work out how to compare the efficiency of a stock vs elec fan blade taking into account pitch, width ectr.
love to see someone explain how to work out how to compare the efficiency of a stock vs elec fan blade taking into account pitch, width ectr.
Shotgun not .
I agree that electic fans use less power than viscous but the difference is so small that I couldnt be bothered with it, my butt dyno wouldnt detect the difference.
DriftZ: "I swear if a CA18 beats my SR im getting a RB!"
a) no more isuzu bakkie sound from your sx
b) more space
c) the electric fans don't work all the time, so yes you save on the rotational mass of the viscous.
d) small weight saving
e) even if the electric fans caused more load on the alternator, the alternator doesn't charge all the time, where as the viscous sucks power all the time.
It's like saying an electric water pump doesn't gain hp because it stresses the alternator more.
--------CFMXPSF
HP= -----------
------ 33000XEfficiency of fan
--------CFMXPIW
HP= -----------
---------6356XEfficiency of fan
-------CFMXPSI
HP = -----------
-------229XEfficiency of fan
Efficiency of Fan = %/100
So who is going to work it out?
Even better, does any of the Engineers here want to work out thermal shock loading when converting to Electrical fans on a system design for verible flow by temperature? or how the cooling frequency changes along with possible cavitational loading?
Maybe something simpler, like how to choose what temperature your new fans should cycle at to prevent thermal waking?
While calculating this, also take into account the viscous clutch. When cold, the fan can be stopped with your hand *don't try this at home, kids!!!*, and only when it gets hot, does it start placing a load on the engine...
Red 200SX S13, 1992, stock. <a href="/phpBB3/viewtopic.php?t=332">Engine rebuilt (click)</a>.
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