Does Anyone Know How Much Cfm The Standard Fan Flows

[DJRIFT]

hi all

i am just wondering if anyone knows what sort of CFM the standard mechanical fan flows on an R32gtst?

i am about to fit a thermo fan and id like to know that its going to flow enough.

i have got a 16" fan which i know flows 1100CFM but is it enough?

thanks damo

[Cubes]

Whats important is the air the fan is sucking is sucked over the whole area of the radiator, not just a select little area near the fan.

You will have to rig up a shroud of sorts. Grab a little sheet metal and bend it up using a few pieces of wood/metal what ever you can get your hands on. Then cut a hole to suit the size of the fan and you have a bodgy home made shroud.

I ran 2 x 12" thermo's directly on the radiator that I remember flowed on paper more than a single 16".

It was fine in normal temps but in heavy traffic with the a/c on it sent the needle to the H. Dropped the std fan and shroud back on and its been as good as gold since.

[mad082]

i thought 1 16" fan pumped more air than 2 12's.

the advantage of thermos is that they run faster at idle than a clutch fan, but the clutch fan gets faster with revs.

i'm just waiting for my 12" thermo to turn up to run as an aircon fan (since it currently doesn't have one). this will be used with the stock clutch fan.

[Adriano]

You could use a single 16 or 18in fan with the standard shroud(although the good fans are bloody expensive)

[DJRIFT]

i was pretty sure the 2 12" fans flowed slightly less but it was a while ago now.

i got 1 16" fan so it could sit in the standard spot. this will still force air through the radiator evenly.

ive gone for a thermo because a you get slightly more power as the engine isnt driving a dead weight. and b for my custom cooler piping as i dont want to cut down the standard fan blades to suit.

it will also be switched off a propper weld in theermatic switch whitch turns on at 84 degs.

but id still like to know the flow rate if anyone has it handy.

[Cubes]

My bad. It does appear the single 16" does out flow 2 x 12" fans, however the 1100cfm 16" thermo fan listed by the thread op flows less than 2 x 12" thermo's. If its a davis fan then they apparently flow up around 1600cfm. I can't find anything solid on it though.

Mad082, I replaced my 12" std a/c thermofan with a single curved blade (more efficient) 14" ebay fan. Has worked well. Made a noticeable difference to the a/c when sitting in peak hour traffic on those 40+degree days.

From memory the single 14" that I picked up flowed ~1400cfm.

[RB30-POWER]

just keep the original viscous clutch fan, way more reliable, flows more air.

thermos are crap on these apps.

your not saving power, as the alternator will be working harder to produce the power to run the fan still, so not sure how it makes car go harder.

also the alternators arent big enough to run all these thermos on idle, your lights will dim at lights and the current from the alternator will be used to run the fans instead of charging the battery.

there is just no reason to change to unreliable thermo fans, you have wiring to get hot, relays to fail, temp sensors to fail. thermos can cause trouble down the track. (usually when you are in the middle of no where...)

[DJRIFT]

just keep the original viscous clutch fan, way more reliable, flows more air.

thermos are crap on these apps.

your not saving power, as the alternator will be working harder to produce the power to run the fan still, so not sure how it makes car go harder.

also the alternators arent big enough to run all these thermos on idle, your lights will dim at lights and the current from the alternator will be used to run the fans instead of charging the battery.

there is just no reason to change to unreliable thermo fans, you have wiring to get hot, relays to fail, temp sensors to fail. thermos can cause trouble down the track. (usually when you are in the middle of no where...)

i understand what you are trying to say but if you had read my post propperly you would have found that i am changing because of where i am running my cooler pipeing. i am running it on more of a diagonal between the radiator and the engine so i need the room and even if you run an off the shelf kit you have to trim the standard fan blades which i think is dodgy.

also the wiring side of things will not be a dodgy back yard job either. i have gone to grate lengths to make sure this wont fail unlike setups ive seen in the past.

all i realy want to know is the flow rate of these standard fans.

and the drain on the alternator would hardly be as much as some tossars subwoofers in the boot so i cant see it being a big deal.

also where i live i dont get stuck in trafic for hours on end and the daily temp rairly reaches 40deg so its realy not that bad.

please someone tell me the flow rate not how to mod my car!

[rev210]

just keep the original viscous clutch fan, way more reliable, flows more air.

thermos are crap on these apps.

your not saving power, as the alternator will be working harder to produce the power to run the fan still, so not sure how it makes car go harder.

also the alternators arent big enough to run all these thermos on idle, your lights will dim at lights and the current from the alternator will be used to run the fans instead of charging the battery.

there is just no reason to change to unreliable thermo fans, you have wiring to get hot, relays to fail, temp sensors to fail. thermos can cause trouble down the track. (usually when you are in the middle of no where...)

No.

There is only a crap install/ crap products not poor concept.

You save power because they are not 'on' when there is enough airflow being pushed through the radiator, usually this is when you want extra power.

The alternator is quite large on RB engines, unless you have a doof doof stereo its fine. If you have a doof doof stereo then you probably already have a bigger alternator.

The wiring doesn't get hot, the relays don't fail, neither do the temp sensors. Had plenty of thermo fans on various cars and none ever gave me the woops.

If you have had a bad experience I can only suggest that if you associate them (thermo fans) with being on all the time that meant whoever set it up did so incorrectly.

[rev210]

Just to add also that if your fluid clutch fan fails or cracks and falls appart you will find it harder to get a replacement in the middle of nowhere. If you have a generic thermo fan, you find every auto shop flogs them in every town.

[DJRIFT]

exactly

[Cubes]

My 2 x 12" thermo's were just setup badly.. Mounted directly onto the radiator so air was only flowing past ~30% of the radiators surface area.

Its a must thermo's use a shroud.

[DJRIFT]

My 2 x 12" thermo's were just setup badly.. Mounted directly onto the radiator so air was only flowing past ~30% of the radiators surface area.

Its a must thermo's use a shroud.

its a must for any fans realy. helps them cover more area.

[VLT025]

So how much do the factory ones flow? ;P

I guess because it varies so greatly depending on revs, it would be difficult to compare them directly to a thermo, which for the most part is 0 cfm or (insert manufacturers claim here)cfm. you would think that 3000 + CFM would not be unlikely at peak revs though.....

[DJRIFT]

yes you would think that the cfm would increase at higher rpms but i think a some point it would then become ineficent to the design of the fan blades and alike. also high rpms usualy mean high speeds where the radiator should see sufcent air flow with out the need of a fan at all. but in some things like drifting and short corce racing than grater airflow is needed.

so still no answer to how much cfm just more questions.

[mad082]

i haven't really ever attributed high rpm in first or second to high speeds.

[Simon-S14]

not sure of actual CFM but the fan stops increasing in speed at approx 4000rpm as this is the max rated speed, and the clutch does it job from there on.

I have fitted my clutch fan back in, and because of the cooler pip[e i had to trim down the blades, Used a large file on the edges with the motor running, then the pipe did the rest, theres acctually quite a fair bit trimmed off the outer edge now... Im guessing as a result im going to be sacrificing some of the maximum rated airflow...Ive kept the thermo fan on the front of the rad... just in case i spose.

[mad082]

i put a 12" thermo on the front of my radiator (on the passenger side where the is a cut out in the shroud for one) and after i hooked it up i put my hand down behind the cut out (after first putting it into the fan.....) and i can feel a little bit of airflow, but not as much as i thought. it is still better than nothing. i have it hooked up to my aircon.

i'm going to put a new thormostat in on the weekend, cause i think my stock one is half dead. it takes ages to come up to temp (about twice as long as the missus SSS pulsar) and even on the highway on xmas day i could hear the clutch fan half working, and round town it was on all the time. i think the thermostat isn't fully opening or closing.