Fan VS Fan

Which fan would use free up more HP over a stock fan, a clutch fan or one of these Flex-a-lite nylon fans? http://www.flex-a-lite.com/catalogs/merchant.mv?Screen=CTGY&Store_Code=heavyduty&Category_Code=400series
I was at the race track last week and spotted alot of cars running these nylon fans and it got me wondering.

There was a dyno test in Car Craft acouple of years ago that tested the different kinds of fans. The winner hands down was a clutch fan which if my memory serves me correctly was 45 HP better than a steel non clutch fan and around 25 HP better than a flex fan. Bottom line is if you have room to use a flex fan, do it. They'll cool the best too.

don

Did the test include that nylon flex fan in the link I posted?
I know the steel flex fan wasn't as good as a Clutch fan for HP, but those nylon one's are only like 11 onces or something like that.
I'm just looking for a few more HP without going to an electric on my commuter.

It's not the weight that sucks the power, it's how much they bite into the air. The amount of power a fan absorbs is proportional to the speed you try and turn it at.

The link you have is for a fan that is designed to move maximum air for a stationary engine. These engines operate over a very narrow rpm range and saving horsepower is not a major concern. I would venture a guess they may even be worse than a stock steel non clutch fan, certainly not something I would hang on the front of my car engine.

Actually it's the same fan (Flex-a-Lite 400 series) that Summit sells for $16.88 and it's rated up to 8,000 RPM and comes in sizes up to 18' diameter.
I'm not sure why that link I posted above to Flex-a-lite said it's for a stationary engine, because here is the same fan on there site again saying it's ideal for a race and performance engine http://www.flex-a-lite.com/auto/html/400-series-economy.html
I guess they're just saying they recommend it for either setup.
I understand about the fan bite effecting HP, and these don't look like they have too much of a bite.
Maybe I'll try to pick one up at the next swap meet, there's usually someone selling them.