ZZZBrahmaBull Posted August 13, 2011 Report Share Posted August 13, 2011 I was told put a clutch fan on would increase horsepower and cooling?Yes or No?Some fans have more blades,pros and cons?Like on a boat 4 blades more torq low speed,less top speed.The 3 blade slow take off but more top speed if I am correct.So hows that work with fans on a car?More air at low speeds with more blades,rush hour city traffic? Link to comment Share on other sites More sharing options...
jwmbishop Posted August 13, 2011 Report Share Posted August 13, 2011 A clutch fan does not increase HP. HOWEVER an unclutched fan robs HP (as much as 25). Under 35 MPH your fan does all the work pulling the air. OVER 35 it creates drag and actually decreases air flow! Thats the reason for the clutch. More blades equals more air - and more parasitic HP loss. The clutch engages thermostatically - that is the hotter the air hitting the front - the tighter (more direct driven) the clutch goes. It is therefore a balancing act between CFM and RPM and Temp. So you have to match the clutch and fan with the app. That can be hard to do in generalization - but many folks have already tried and tested and you can get fan\clutch combo all ready to go from many various suppliers. Link to comment Share on other sites More sharing options...
4cylfordz Posted August 13, 2011 Report Share Posted August 13, 2011 running a fan clutch is a good idea however on most 1/4 3/8 mile tracks the straights are not long enough for the silicone fluid in the clutch to cool down enough to turn back into a liquid so it probably won't ever unlock. you would have better success with a smaller fixed blade or an equal size flex fan with a shroud Link to comment Share on other sites More sharing options...
jwmbishop Posted August 14, 2011 Report Share Posted August 14, 2011 Good point. Add to that when racing you are hopefully making more heat and removing more of the heat into the air stream that controls the clutch. Most stock clutches tends to overreact and lock even more. I have always liked the flex because of this. I had good luck with a non thermal - But you have to rev the engine higher to cool down on yellows. Link to comment Share on other sites More sharing options...
4cylfordz Posted August 14, 2011 Report Share Posted August 14, 2011 you are right on with your comparison to boat props, hince why you will see that the fan on a diesel truck has many blades though it will spend most of it's time at lower rpms vs a small engine will only have 4 blades since it will spend more time at higher rpms. the important differences (for racing at least) are in diameter and pitch. blades count only determines the the fans efficiency at X revolutions. that being said less blades is better since most race cars spend very little time under 2500rpm. Link to comment Share on other sites More sharing options...
thumper Posted August 14, 2011 Report Share Posted August 14, 2011 The best fan blade I found for my V8 Fords and Chevies were the 4 blade that are actually 2 blades that cross each other.No trick shapes or designs,no breacing problems,pleanty of cooling with not a lot of drag.They were used on the old 50s and 60s V8s.I have a pile of fancy blades,different sizes,pitch,# blades etc but always went back to these old blades.I dont know why,they just work,even at 8000 rpm. Link to comment Share on other sites More sharing options...
JamesHigdon Posted August 15, 2011 Report Share Posted August 15, 2011 Not to try and steal the thread but along the same lines what is the general feeling on a flex fan? I would guess the RPM turned on a short track (especially a dirt track) would make them almost useless but I have no solid info? Instead of guessing I might as well ask. Link to comment Share on other sites More sharing options...
thumper Posted August 15, 2011 Report Share Posted August 15, 2011 Too dangerous with flying pieces. Link to comment Share on other sites More sharing options...
HiTech Posted August 15, 2011 Report Share Posted August 15, 2011 been running plastic fan blades for years ..light wieght .never a loss of water pump ..never came apart ...never had one problem with em ..dont know what the fan speed is at 8000 plus rpm.s but year after year they hold together ... Link to comment Share on other sites More sharing options...
4cylfordz Posted August 16, 2011 Report Share Posted August 16, 2011 most flex fans will start to give around 3500-4000 after that they will run flat. decreasing drag on the pulley, they get their bad rep from people running factory flex fans as with most parts the more money you spend the better they are. depending on what pulley setup you got you it could be turning in overdrive so be sure you consider the rated rpm of the fan or you will have a holey hood Link to comment Share on other sites More sharing options...
HiTech Posted August 16, 2011 Report Share Posted August 16, 2011 most flex fans will start to give around 3500-4000 after that they will run flat. decreasing drag on the pulley, they get their bad rep from people running factory flex fans as with most parts the more money you spend the better they are. depending on what pulley setup you got you it could be turning in overdrive so be sure you consider the rated rpm of the fan or you will have a holey hood talk aboult holey hood ..one of our cars back then didnt have that problem ..the blade went right through the inch and a quarter .by 125 thousands pipe . sliced right through it ..sure glad no one was beside him dureing that flying piece . Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.