esisson

3 dumb questions: (actually, 2 decent and 1 dumb question)

There are 6 blade fans and there are 7 blade fans. Can anyone tell me if the OEM cooling fans for Olds is model specific, engine specific, or other?

Also, is it safe to assume that a 7 blade fan has more cooling capacity than a 6 blade fan? Common sense says "yes" (more air flow), but I'd like to hear a more scientific explaination if possible.

Also, Do you think a 7 blade fan is noisier than a 6 blade?

Thanks in advance.

BILL DEMMER

there were also 5 blade fans and 4 blade fans. 4's were typically used in non-a/c equipped cars, 5's were usually the standard v-8 a/c application fans, 6's were the heavy duty fans, and 7's were for the diesel's or toronado's.

the 7 blade fan doesn't necessarily move more air, the blade pitch has to be taken into account. they could use more blades with a smaller pitch to help keep fan noise down. basically there are several factors involved. blade pitch, size, and shape are what pop into my mind, right off the bat. the early toro's got 7 blade fans due the small grill area on those cars, the diesel's got them because they ran hot. it stands to reason that with all other factors being equal, more blades should move more air and make more noise doing it.


bill

Olds64

Do all of the fans fit inside the same shroud? If so, why doesn't everyone change to a 7 blade fan unless they don't like the noise or are going for originality?

J-(Chicago)

Are you curious because you have a cooling issue already?..... Or because you wish to avoid one in the future?

In my experience going from a 5 blade fan to a 6 or 7 blade fan on the snout of the water pump makes little noticible difference.

If you bolt 1 electric fan against the radiator, you will notice the difference right away.

BILL DEMMER

the more air you move-the more power you steal from the wheels. if you don't need 7 blades, you would be wasting the power it steals. now, it's not really going to change your quarter mile times much, but too much doesn't accomplish anything.


bill

Olds64

True. I was just curious. My 71 98 is running fine.

esisson

I picked up a 7 blade fan from a Toronado at the local junkyard. It was cheap and I was just pondering whether or not to install it. I'm not currently having any cooling issues, just curious as to what they commonly came on.

Observation:
The 6 blade fan is about 9 inches and the 7 blade from the Toro is about an inch smaller which might eliminate some clearance issues people may have with their fan shrouds.....

Lady72nRob71

A 9" fan?
That was the fan size on my sisters old hundai excel...

You must have meant 19"...

esisson

LOL! You're right. I fat fingered that one. Thanks.