LOL - what junk. Hit the scrap yard for any shrouded electric fan and relay.
Pretty sure the parasitic losses rule of thumb is about 5-6hp of drag through the alternator.
Anyone Feel Like Running a Mechanical Fan?
- Thread starter motorheadmike
- Start date
- Status
LOL - what junk. Hit the scrap yard for any shrouded electric fan and relay.
Pretty sure the parasitic losses rule of thumb is about 5-6hp of drag through the alternator.
Thanks for posting. Data is great to have. Another advantage of electric fans is that the ECM can turn them off at WOT.
Glad I switched from the factory 4 blade fixed in my 70S to dual electric fans for free horsepower. Mine didn't have the shroud, which did help. Foxtrot used the same 4 blade fan on the 403 in his Buick Regal, it cooled very well on his car. I was going to buy a cheap flex fan for the 260 and keep my fixed fan as back up, I need to rethink this maybe.
What about the added drag of spinning an alternator powering an electric fan?
The clutch fan also has more bite when it senses hot radiator air flow.
It would be more realistic to see the 'as driven on road' test numbers of the various fan options.
Take it to the strip and find out which combo gives an extra mph at the finish.
How about a spoked mag wheel vs full wheel cover wind resistance effect on 1/4 mile ET's?
The clutch fan also has more bite when it senses hot radiator air flow.
It would be more realistic to see the 'as driven on road' test numbers of the various fan options.
Take it to the strip and find out which combo gives an extra mph at the finish.
How about a spoked mag wheel vs full wheel cover wind resistance effect on 1/4 mile ET's?
Last edited:
I already covered that - 5-6hp is normal for frictional losses in the alternator. New cars actually have programmed load adjustments in the ECM for accessory drag.
The calculations for reductions in reciprocating mass at the crank, driveline, and wheels are readily available on the web.
It is hard to argue just how pathetic mechanical fans are for power consumption. They are fully justified if max cooling potential is the root issue. But, please talk amongst yourselves.
How exactly can a person scientifically test the effects of a mechanical fan at the track when a person can barely run 2 of the same times at the track with 10 passes? You'd need to take at least 10 passes to get a control or average, then do the same with each fan, only to be +/- .** in the first place. At least that's how I see it.
but my car is slow and I still have a mechanical fan so my knowledge is limited lol
I don't doubt that removing the mechanical fan improves the efficiency especially once other engine mods are done. I think it's effect would be more noticable on a lower powered engine. Other benefits are better fuel efficiency and less noise due to the cooling being on demand.
Good news: it is significantly less than that.
See below.
There is a reason he throws out the 1 HP figure. Years ago for an article in Car Craft, they did a huge dyno comparison of eight different mechanical fans. Not only were they comparing fan types, they also wanted to see if an electric fan really made more power... so they threw one of those into the mix as well.
Following proper procedure, they did a baseline test of the engine itself--no fan at all, and no alternator. That setup made 496.0 HP.
Next, they bolted on a 63-amp 10SI alternator but did not connect any sort of fan. Now the engine made 495.0 HP.
Then they plugged in Flex-A-Lite's most powerful single fan, the Black Magic 150. Power output dropped to 494.4 HP.
Going from no fan and no alternator to a running electric fan and an alternator only cost 1.6 HP total.
The best mechanical fan in the group was a thermal clutch fan. With it hanging off the nose, power dropped to 486.7 HP. This means the most efficient mechanical fan they could find still took away another 8 HP compared to the electric one. Be aware, though, that they also dyno tested two other clutch fans... and those only made 484.6 HP and 476.4 HP, meaning they cost you 10 HP and 18 HP respectively. Long story short, your clutch fan is costing you anywhere from 8-18 HP compared to an electric setup.
FYI
- Status
Similar threads
