CFM Ratings

[IfItsGotWheels]

I've read several threads on electric fans, but as far as I can tell no-one has asked the following question.

What are the cfm ratings on the different factory fans at idling speed?

 

[rumblefish360]

Good question.

All I. An say is after a few electric fan set up that I have tried, I'm sticking to the factory Viscous fan with a shroud!

 

[67Dart273]

I think the question should be more "what works," that is, what have "you" "the other guy" used, did it work.

Here's the thing. YOU CAN NOT publish a cfm rating without knowing specifically what restriction is in the path. That is, "what radiator." "What shroud" And so on

The second thing is, "they lie." My favorite lie to pick on is air compressor ratings and electric motor HP. This new thing rating motors by amperage is no better. If I, the Chneseo guy, make an inefficient motor that makes a lot of heat, sure it draws "big amps." But it does not put out any power

Sorry for the downer. Welcome to the world.

 

[RustyRatRod]

Good question.

All I. An say is after a few electric fan set up that I have tried, I'm sticking to the factory Viscous fan with a shroud!

That's because MOST electric fans are play toys. Until you approach or eclipse 4K CFM, you're really not doing a performance V8 any good. Most people don't want to spend the money on a REAL electric fan. I don't really blame you. Cause I don't either. lol

 

[RustyRatRod]

I think the question should be more "what works," that is, what have "you" "the other guy" used, did it work.

Here's the thing. YOU CAN NOT publish a cfm rating without knowing specifically what restriction is in the path. That is, "what radiator." "What shroud" And so on

The second thing is, "they lie." My favorite lie to pick on is air compressor ratings and electric motor HP. This new thing rating motors by amperage is no better. If I, the Chneseo guy, make an inefficient motor that makes a lot of heat, sure it draws "big amps." But it does not put out any power

Sorry for the downer. Welcome to the world.

I think those CFM ratings are surely unrestricted. Just measured with the fan wide open. I only trust one or two companies ratings anyway. Most of those ratings are bullshit.

 

[inkjunkie]

I agree with the ratings aint worth a crap. Can say I have had nothing but grat success with Spal fans. Had a 16" inch one mounted in front of the a/c condenser to help with the a/c when I got rid of the r-12. Got curious one day and took off the factory belt driven fan and went for a ride.....manged to keep the coolant temperature the same as when the belt driven fan. Granted, it was only a 4 cylinder in a Ranger....but like I said it was mounted in front of the condenser...and it was only 110* out.....

 

[krazykuda]

Yes, not so easy of a question to answer.

If they did rate them in CFM, then they would be rated "unrestricted" which will not accurately predict how they will perform in "your" particular application (as your restrictions may be different).

Then, yes, you can't trust the ratings of the manufacturers. When I worked in the engine factory, our big v-6 was rated at 220 HP and would dyno between 170 - 180 for our production engines. Our small v-6 was rated at 180 HP and would dyno between 130-140 HP on our weekly dyno audits (I was the only guy that actually LOOKED at them). I asked the head engine design guy why our production engines dyno 30 HP less than they are advertised at. He replied, "We built ONE that put out that much..."

I said, "As a customer I could do not care what you "are capable" of building, I want to know what "MY" engine puts out...."

Yeah, they built a prototype engine with CNC'ed ports etc, and that's what they use for the "federal test" certification.... What bullsh!t....


Not like the old days where the 340's were rated at 275 HP and put 285 to the back tires...