RotaryEvolution

iTrader: (30)

problem is usually efan ducting, those circular fans with no ducts are garbage and should be outlawed. a fan can pull 10,000CFMs but it it is only pulling air over 1/2 of your radiator core then the radiator is only working at 50% max efficiency.

had a customer recently ignore my advice and got a Spal fan with no shroud, covered 50% of the core. guess what? it immediately ran hotter and worse than it did with the stock clutch fan.

SirCygnus

iTrader: (1)

im willing to bet that if the fan is shrouded properly, it will work just fine.

clokker

iTrader: (2)

I think you overestimate even this terrible coverage because usually people forget that you also have to subtract the area of the fan hub (which can be quite large on a OEM fan).
The "dead spot" under the fan hub can be mitigated by raising the fan off the rad surface; there are formulae to figure out this arrangement but given the practical constraints of the engine bay, it's safe to say that the further you space the fan away, the better.

Using the stock shroud as a start point would be good but I've found it impractical in real life.
It won't fit with a thicker aftermarket radiator and even if it did, the shape was compromised by the big indent for the airbox snorkel to lay in. Quite a bit of the blade is masked along the top radius.

The Ford fans (Taurus/Lincoln) have very serviceable shrouds for our application, the Volvo fans have the most elaborate shroud setup, featuring bypass flaps and a bolt on fan assembly.

A simple fan (no matter it's quality) clamped directly to the core (typically using the fin destroying push connectors) is about the worst case scenario for mounting an efan.

Rob XX 7

iTrader: (8)

and im willing to bet the fan is junk

im thinking about this volvo fan set up now, I really think the taurus fan's shroud is restrictive at highway speeds.

clokker

iTrader: (2)

I have a set of Volvo bypass flaps that I've considered grafting to the Lincoln shroud I'm using, seems like it'd be the best of both worlds...the big 18" fan and highway bypass all in one (Volvo fans are 16", Taurus are 17").

Rob, how would you determine if the Taurus shroud is restrictive or not?

Rob XX 7

iTrader: (8)

Clokker- I had a 3800cfm or something fan and shroud that covered the whole radiator, it was a custom piece that really looked nice but I always felt the fan was running too much and at highway speeds it restrictive.

I switched over to the taurus fan because of everyone's positive reviews and it was much much better then my "3800 cfm" fan set up.

But I do blame part of it on the fact that the taurus fan shroud doesnt cover the entire radiator core, and my old one sealed it off completely only allowing air to pass through the fan before exiting.

I think at highway speeds if some air was allowed to pass through the shroud it would keep the fan from coming on less often

SPAL USA


Shroud Flaps
Since additional airflow proved beneficial to overall performance, Shawn Kenney of PRC and Heath Langenfeld of SPAL suggested that in a small percentage of applications the fan shroud could prove to be a restriction. According to Langenfeld, "Moving from a factory fan shroud opening of 21 inches down to 16 inches restricts the volume of air flowing through the radiator. The reduced diameter of the hole has a funnel effect and on big-cubic-inch applications, it is often necessary to make alterations to the shroud. To cure the problem, we recommend installing rubber flaps onto the aluminum shroud. They will remain closed at slow speed and then open up at high speed to allow more air to flow through the shroud."

After testing the rubber flaps, the performance on the 10-mile highway test improved, allowing the car to run right at 200 degrees. Compared to the earlier final A/C seal kit test, the low- and high-speed cylinder head averages of 176 degrees and 185.5 degrees were up a bit but so, too, was the ambient temperature, at 92 degrees.

Having proved that increased airflow was beneficial to overall highway performance, SPAL suggested that the shroud be removed and the fan mounted to the radiator core. As you already know, that final setup showed the best performance (see Test Results).



Read more: Pontiac Cooling System Upgrade - High Performance Pontiac Magazine

clokker

iTrader: (2)

Ah, I see...your fan activates whilst highway driving.
My weenie little NA doesn't get that hot, fan has never come on over 40-45mph sustained speed.

The flaps are a good idea anyway, I really like the ones with support cages that limit flap travel. Lots of the ones I see in the yard have flaps permanently curled to a semi-open position.

Rob XX 7

iTrader: (8)

if you are NA, obviously no FMIC, and no AC you could probably use just about anything to keep the car cool

clokker

iTrader: (2)

Yes.
I frequently comfort myself with factoids like that as I'm being passed by a Prius.

sharingan 19

iTrader: (16)

^^^Lol.

The nissan quest shroud covers the entire rad and most certainly becomes a hindrance to air flow at highway speeds. I was strongly considering retrofitting some of those flaps or going to a volvo fan/shroud but I ended up going v-mount and forgot about the idea.

This same effect is present even with no shroud. On my V-mount I have to run 2 10" fans due to space constraints and even just the fans themselves present a noticable obstruction to airflow. If I get on the highway before the fans come on temps will never rise above 180*. However if the fans are running (on at 195* of at 185*) when I get on the highway temps will quickly drop to around 185 and hover there for a few miles before dropping to 180* or so , where they stay for the rest of the trip.

jackhild59

iTrader: (7)

Factory systems with A/C on run the electric fans all the time (with a few exceptions) even on the highway. On my 2004 Mazda6 the coolant runs at 195* with the A/C on and the fans run continuously. This is the coolant Thermostat opening temp. If I turn the A/C off the fan goes off, the temps rise to 213*, the fans turn on, the temp drops to 201* the fans turn off. (temps logged from the OBDII port) Lather rinse repeat.


If your goal is to have the electric fan turn off on the highway, you will most likely be disappointed (except for clokker). If your fan is controlled on at 212* and off at 200* you might see it go off occasionally in cool weather.

I have done testing on my 90 vert fan with a disable switch. I know that my coolant temps run cooler on the highway (A/C on) when the fan runs. I also know that the coolant runs cooler on the highway (A/C off) with the fan on.


The desire to have the fan turn off on the highway is based on a misconception that the factory mechanical fan 'freewheels' on the highway. It does nothing of the sort. First of all, the viscous coupling is physically unable to completely disconnect. Data Sheets I have found on aftermarket factory replacement thermo-viscous couplings state minimum of 35% of the hub speed. Full lockup is +/- 85% hub speed. The pulley ratio is 1:1.123 . So when the car is at highway speed, 3000 rpm and everything is *room temp* the fan is being run at 935 rpm (3000/1/123*.35=934). Try to tell me that fan is not moving some air and using some power. At high temps, the fan is at a maximum designed speed 2270 rpm.



Fan laws tell us that CFM (air flow) is proportional to speed. Since we don't know either actual CFM we can still calculate that the air moved in this example (3000 rpm) at the coolest temperature in our example is *at least* 41% of the air moved at the warmest temperature!

What have I missed here? Oh, yes-At what temperatures does the max and the min rotation occur? I cannot find data for the FC unit. but I can find trouble shooting info for a Borg-Warner Bimetallic valve operated unit of similar design.

http://www.ets.borgwarner.com/PDFs/S...ins/sb1005.pdf

Steves13b

iTrader: (9)

What year and model Volvo has that fan? Is it a one or two speed? Having trouble finding threads containing info on a Volvo fan. I'll spend my next days off checking all the local auto wreckers.

jackhild59

iTrader: (7)

It's a two speed fan. You will find it on Front Wheel drive models.

Steves13b

iTrader: (9)

Well, I realized that I set my igniting timing when my tps was WAY out of adjustment, set the tps, re-set the ignition timing and so far my car has been running significantly cooler, haven't gotten to drive it too much but I did drive it and replicated what would normally make my temp gauge rise and it didn't warm up one bit, pretty relieved but I won't get my hopes up until I really get to put my car through its paces!

SirCygnus

iTrader: (1)

dumbass

clokker

iTrader: (2)

Is that a fair comparison, I wonder.
Doesn't your Mazda 6 have two smaller fans (are they push or pull?) on a smaller radiator?

bmwrx7man

iTrader: (2)

im still having this problem not as bad as before . went todyno made 292whp . pretty hot out today like 95 degress . fan on 2nd speed i cut the shroud around it . still half temp on highway whole time back home 20 min drive when its cool outside dont get that hot . yes my under tray is back on hood tilt also driving around the city its nice . im really about to put back on the top mount ic

Rob XX 7

iTrader: (8)

Drove my car with no boost (had no IC pipes ), 90 degrees about same humidity, car was running 184 on the highway, I made this trip 2 times, amazing difference when no boost. Stop and go never went over 190 or so when the fan triggers