Printable View
Want opinions on this? Keep hearing the Serpentine setup can help cooling a lot as well. Have a 427ci Dart Block/Head Motor in a new car for myself. Won't be turning over 7200-7500rpm. Have a 15" 6 Blade fan with V-Belts but was told it would be beneficial to change. It runs an ATI Superdamper with a Bolt on V-Belt Pulley, KRC head Mount Power Steering pump and the short style water pump all V belt. What would be the best setup. Not concerned about HP loss just want maximum cooling potential.
1. How would belt type change cooling ability unless one had more/less belt slippage?Quote:
Originally Posted by 7uptruckracer
2. Don't think there is much argument that a serpentine uses less power then a V belt.
3. My problem with Serps are early on they tended to slip due to the small pulley diameters (thus very small length of belt contract with pulley) and needed more rap around on the pulley due to this fact. Many of the early ones incurred belt slippage and caused overheating.
4. The V belt has been used for years with little problems and a pretty proven commodity.
The slippage is where I’m going with this. Just was told that wants a V-belt in V belt pulley get a little bit of where they slip a lot more than serpentine belt just the season I’ve noticed a lot of the guys that I help going to serpentine systems and was told that they slip less so it will cool better.
Quote:
Originally Posted by billetbirdcage
Dang talk to type. Once the V belt gets wear it slips a lot more *
All I can tell you is when they first started making the serps, they were typically a very small diameter, like 2.5" diameter pulleys. This when ran as a typical set up going to an alt or PS pump, when the belt only rapped around the water pump pulley 90 degrees it had about an 1.5" of total belt contact. This wasn't enough to not slip the belt fairly easy. This is why later on they added an idler pulley to increase the rap around the water pump pulley and stop the issue. So many people had issue's with this it wasn't even funny, but as I said was years ago.
Also once they slipped much and burned off the anodizing (without the idler pulley) they were pretty much done and adding the idler didn't help, you needed new pulley's with the idler.
Like I said the newer stuff is probably a lot better as I'm pretty sure they increased the pulley diameters to increase belt contact area, but have no first hand info to say it's cured for sure. Before I'd try a serp again I'd have to be sure it has a decent amount of belt contact from a larger diameter and more belt wrap around. Personally, I see no advantage over a V belt besides power loss as a correctly done V belt will Not incur more belt slippage then a serp, but that just my opinion.
Basically I seen too many people burned by the early ones, that I'm extremely suspect of serps in general and very reluctant to fix something that was never broken in the first place. Maybe I'm just getting old, lol.
What kind of power difference is there?
Very true. It had never com across my radar till recently to even consider switching but
The guy stomping ass ever week brought it up when he was looking over my new stuff, figure I would see if any new theories were out there
Quote:
Originally Posted by billetbirdcage
No idea, but I doubt it's much. Even if it is, how often does 5HP win you a race because you had that extra HP.Quote:
Originally Posted by zeroracing
If you have cooling problems then go with the proven 19" 4 blade GM fan.If your hunting hp look somewhere else.
Billet,
I have been trying to figure out why guys run them, I am in the same boat as you, v belts are broke and I assumed did not take much power but did not know if somebody had tested it. look nice, but lots of better ways to spend money on the car.
HP is far from a concern, this isn't a LM application but OWM, but we are running no nose opening preferably and sealed to the track completly this us just where the best info is. Just trying to compare the two belt systems alone and was told V belt will slip more then Serp. All I have to turn is PS, WP and Crank. It has V belt now. The nose has a plate attatched with Dzus fasnters to open nose I see no need to run it open if i can keep it cool but the car is new to me. I was told to go to a 6 Blade fan because it cools better and Serp because it won't slip like a Vbelt and that will help cooling as well.
Quote:
Originally Posted by perfconn
The 2 blade Race Fan will solve your cooling issues, I wouldnt worry about your pulley type unless you are slipping. I use V belts with a 2 blade Race Fan which is 19" and dont have slippage or cooling problems. The fan is modular so you can add up to 6 blades, it pulls some serious air. The 2 blade pulls about the same air as a steel 4 blade 18" Allstar fan and weighs significantly less.
Can you explain why a 2 Blade works better then a 4 or 6? I always thought the more blade the more air?
I wonder if at some point too many blades just creates a "wall" so to speak, and doesn't move as much air as fewer blades would. Of course, I assume actual blade size (surface area, etc.) and pitch would play a factor. Maybe similar to an airplane prop? Most small planes just have a two blade prop, other larger ones maybe three or four (on wing mounted engines). And I'm by no means an airplane guy, but trying to compare/think out loud...
I don't know the real answer but three things come into play with fans blades/Propellers. I'm no expert nor and aeronautical engineer but I do like to hang out at the airport with my racing friends.
Tip speed
Blade length
Chord length
When the tips become supersonic the efficiency declines and noise increases.
When blade length is longer the tips go supersonic at a lower rpm.
Chord length and shape have effects of the power required.
In dirt racing, power consumption is secondary to moving the air, noise isn't a concern until the tips go supersonic and decrease the efficiency. By that time however, the car is already moving forward fast enough the ram effect has considerable notation.
Pulling an airplane through the air is NOT the same as pulling air through a medium like a radiator. The fins of a radiator help somewhat by reducing turbulence.
So what I'm saying here is the 2 blade fan likely works well(not always better) because it's lighter and uses less power and has favorable efficiency mostly due to chord shape.
On the the other hand some people go faster because their wallet got lighter.
On the pulley debate, Serps tend to have more surface area for grip until, like Billet says, the diameter or wrap percentage overcome this. Less belt tension is needed and they tolerate misalignment better as well so belts last longer and materials for pulleys are less. I'd say that the main reason why all modern OEMs use Serps.
There's also an argument for bearing life at the front main, the water pump, and the PS pump or alternator if it applies from over tightened V belts.
Dirt racing, in my opinion again, a properly set up V belt gets the job done pretty cheap but a Serp get's the job done too but with some minor value ad on's.
Great info from everyone! Hey @Lizardracing, can you explain what "chord length" means? I haven't seen that term before, but assume it has to do with the surface area of the blade? Thanks!
Fan blade width....as drawn from a straight line.
If you cant turn your motor over by hand with your fan you have slippage. V belts start to wear the pulleys the minute you start the car as well as wear the belts.
They sell a tensioner or idler set up for serpentine, you can get it as tight as you want and it will stay that tight.