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hotrod1994 07-06-2013 11:24 AM

cooling
 
dual 12 inch fans or a 16 inch single witch one is gonna keep me cooler?

fast75vega 07-06-2013 01:01 PM

i run one 16 inch fan on my car but i tried the dual first... used alot of juice and didnt seem to cool as well

TheYellaBrick 07-06-2013 03:45 PM

What is the application ?
Intended use of said car ?

hotrod1994 07-07-2013 01:04 AM

well it gonna have a sbc with around 450 500 hp right now its a mild sbc with apx. 350 hp
street car
it got a 160 tstat right now and when cruising its fine runs 160-190 depending on temp outside but with my flex fan and shroud at and idle it will climb to 220-230 and keep going if i don't shut her down
its got a 3 core aluminum radiator

looking to stay cool at idle

thanks, logan

TheYellaBrick 07-07-2013 07:13 AM

Change that water pump to a Flow Kool. I've been having cooling issues for years with the stock pump in my race car, changed it out to a Flow Kool and ELIMINATED ALL cooling probs. :shock: :shock: :shock: :shock:

roadkill2 07-07-2013 08:30 AM

This is a "toe dance" . . You have to flow enough coolant through the radiator to cool it to 140 at the bottom or inlet hose on just about any gasoline engine being made today. The temperature going in at the top is a moot point, but the bottom is very important.

Dunno how big your fan is and how tight it fits in the shroud, but normally, unless you have an engine or a flow problem, a 15"-16" flex fan with about a half inch clearance at the fan tips to the shroud should cool it efficiently on both ends of the rpm spectrum.

It sounds to me like your raditor isn't getting enough air to it at low speeds. Or, your radiator hasn't enough capacity. I say that because if it was too much flow at low rpm, you should have heating problems at much higher rpm, or all the time.

Rule of thumb is; "The more coolant in the radiator and the longer it's in there, the cooler it is on re-entry to the engine" . . .

hotrod1994 07-07-2013 11:58 AM

hmm i think ill look into a flow kool water pump and prolly an elcetric fan
thanks guy!
,logan

chevynovaman 07-07-2013 05:36 PM

COOLING
 
LOGAN

I HAVE TRIED DIFFERENT PUMPS, FANS, THE ONLY THING THAT EVER HELPED WAS A BETTER RADIATOR, SEE U AT IOLA R C

fast75vega 07-07-2013 07:04 PM

im sure im not the only that will say this.... but that "flex" fan has got to go... they are junk :wink:

hotrod1994 07-08-2013 11:49 AM

yeah i dont like it either

roadkill2 07-08-2013 01:33 PM

An electric fan won't cure your problem . . Or at least, they generally don't . . nor will a different water pump.

Low speed heating tells me that you aren't flowing enough air through the radiator, or . . The radiator doesn't have the convection tubes necessary to carry enough coolant through that radiator.

When did this heating problem start? What did you change before it manifested itself?

I'm not being a hardass, but you sound like you're ready to spend a bunch of money to keep the problem you have right now . . .

Another thing. If you're just going to drag race it, start with an adequate radiator, and then put a single electric fan on it that covers the whole radiator back with it's shroud. NEVER put the fan in front of the radiator . . Simply because you put all the motor and shroud supports in front of the fan and cut it's efficiency by about a quarter . .

markdunlap 07-08-2013 04:30 PM

cooling
 
You can pull a lot more air thru a radiator with an electric fan than you can push. Your creating a low pressure area in the direction air wants to go anyway.

Pushing air with circular fan thru fins is like trying to push on a rope.

hotrod1994 07-09-2013 12:00 AM

well it always gotten hot at an idle ive tried 180 t stat the 160 no t stat at all and its always gotten hot at an idle, i can hold it 2500 at a stand still and it will kool down to 190-210 and stay there as long as ive got it at around 2500 if i let it idle it heats back up

i dont see the radiator being my problem as my old man ran a stock 2 core brass/copper radiator with a flex fan in his nova with a big block that ran 10.50's in the 1/4 ran a steady 220 temp, my 3 core aluminum has got to be better than an old brass/copper 2 core

so i should get a fan to pull air through the radiator is what you guys are saying?

wmeabates 07-09-2013 04:01 AM

If You have some extra pulleys try a smaller one on the pump,or a bigger one on the crank.That will speed the pump up.Maybe both but don't exceed the rpm limit of the fan blade,very important. Sometimes less mechanical advance in the dist. and more advance at idle will help at low speed also.Bill.

itsabird 07-09-2013 05:54 AM


Originally Posted by wmeabates
If You have some extra pulleys try a smaller one on the pump,or a bigger one on the crank.That will speed the pump up.Maybe both but don't exceed the rpm limit of the fan blade,very important. Sometimes less mechanical advance in the dist. and more advance at idle will help at low speed also.Bill.

Yep also check carb settings, i would also drop the flex fan, they are designed to reduce drag on the engine, imo with smaller blades, coupled with any flex that may happen at low idle. low speed cooling, is compromised.

roadkill2 07-09-2013 06:10 AM


Originally Posted by wmeabates
If You have some extra pulleys try a smaller one on the pump,or a bigger one on the crank.That will speed the pump up.Maybe both but don't exceed the rpm limit of the fan blade,very important. Sometimes less mechanical advance in the dist. and more advance at idle will help at low speed also.Bill.

This is the "toe dance' I spoke of earlier . . You say, one, "it's always done it" . . and if you run up the rpm to 2500, it cools down . .

This means . . You're pulling enough air through the radiator to cool the radiator you have currently at 2500 rpm. You need either more air, or more radiator. Now, "more radiator" doesn't necessarily mean a bigger one, but one that's more efficient. And what works in one application doesn't necessarily fit another. You're dealing with efficiency of convection here.

IF . . you overdrive your water pump to compensate for the lack of radiator, you will still have the same volume of cooling fins but you'll be flowing coolant at twice the speed you have now . . Which will cause heating at both ends of the rpm spectrum.

Here's the Temps you should be looking for on a SBC . . with a 180 thermostat, @ the Gooseneck; 185-195 . . Back of Radiator at the top hose inlet;195-200 . . at the bottom hose or engine inlet; 140 . . This is the important one! Get it right and the rest will fall into their right places.

Bill hit on another thing you might check, but I'm sure you already have, and that's timing. If it's retarded below about 10 at the crank, SBCs will heat at lower rpms . .

One more thing . . Location of your sending unit. Ideally, it should be in the Left head in the plug location right behind the #1 header pipe . . If it's in the reverse side between 6 & 8 or at the gooseneck (on a lot of later GM Cars) you'll get hotter readings at lower rpms, dunno why, other than ambient surrounding heat. The sending unit or plug at #1 in the head will read about 155 if the engine heat at the thermostat is 180 . .

IF . . you get the radiator right and the correct speed of coolant the mechanical fan will do just fine . . until you decide to put all that neat stuff that racing engines have where the fan would go. Then you'll need the biggest "S" style electric fan, preferably with a manual switch, you can get . . BEHIND the radiator . .

itsabird 07-09-2013 10:25 AM

Are you useing the edelbrock carb?

hotrod1994 07-09-2013 12:19 PM

ok well im gonna have to start figuring out what the problem is
and its a holley
thanks guys

hotrod1994 07-09-2013 12:22 PM

how should i go about checking the the temp at the bottom hose on the
radiator? ir thermometer?

and the flex fan is 3-4 inches away from the radiator so ive got a felling its not getting enough air flow

TheYellaBrick 07-09-2013 12:30 PM

HO KAY now we're getting the real skinny here. Flex fan at 3-4 " even WITH a tight shroud will not pull enough airflow at idle. I might have missed it ,but I don't see where you even mention having a shroud at all. SHROUD-SHROUD-SHROUD properly fitted and no more 1/2" clearance at the blade tips.

hotrod1994 07-09-2013 03:40 PM

the stock shroud is tight real tight like 1/4 inch of clearance i never had one before and it helped a little but not enough
maybe ill try spacing the flex fan out some more how far away should the fan be from the radiator?

TheYellaBrick 07-09-2013 05:02 PM

Moving that flex fan deeper into the shroud won't help a bit. Change out to a stock type bladed fan or clutch fan or electric pull type.
The flex fan design is made for it to turn into a low drag disc at speed, and as such will prevent larger airflow rates through the flattened blades.

hotrod1994 07-09-2013 05:44 PM

ok so mount the electric fan on the engine side of the radiator and pull the air through right?

bjuice 07-09-2013 07:16 PM


Originally Posted by hotrod1994
ok so mount the electric fan on the engine side of the radiator and pull the air through right?

Hint ......

Just make sure the fan's polarity is wired properly and the fan is pulling indstead of pushing if your mounting on inside of radiator. This mistake can be made pretty easy if you do not check the pull of the fan before you final mount.

hotrod1994 07-09-2013 11:55 PM

yeah i planed on checking it
thanks guys
i appreciate all the help

roadkill2 07-10-2013 06:49 AM


Originally Posted by hotrod1994
how should i go about checking the the temp at the bottom hose on the
radiator? ir thermometer?

and the flex fan is 3-4 inches away from the radiator so ive got a felling its not getting enough air flow

1) Use a IR temperature gauge. You know, one of those with the laser dot for aiming when you pull the trigger. If you don't have one, you don't have one of the right tools to be drag racing . . You use it for everything. Engine temps, header temps to see if all cylinders are firing, track temps, tire temps, even wife temps . .

It doesn't matter how far from the radiator the fan is, if it fits in the hole in the shroud with about 3/4" all around it. The fan should also centerline or be just slightly inside the shroud. Preferably the Fan blades should be at least an inch or two (or further) from the radiator. The fan creates a vacuum in the shroud and pulls air through the radiator and the closer to the radiator it is, the less area is exposed to moving air. In other words, if you have a 17" fan and it's a quarter inch away from the Radiator, you're only using a 17" circle in your radiator to cool your engine.

On the Flex Fan. It should work just fine for the symptoms you have described. A "Flex Fan" is designed to flatten out as the fan's rpm increases and to pull LESS air as it does. At low rpm the fan's efficiency is the greatest, and the least at high rpm . . it's designed to create less parasitic drag or HP loss at higher rpms where you have moving air that takes the place of the need for a fan . .

The problem with any mechanical fan in racing applications is that they're generally riveted together and tend to come apart at really high rpms . . And if you've got an engine you're gonna buzz into the real high 6's or touch 7000 rpm plus, you should go to a constant speed electric water pump and an electric fan. It's just one thing less that's sure to fail, sooner or later . .

oldandtired 07-10-2013 06:56 AM

[quote="roadkill2"]

In other words, if you have a 17" fan and it's a quarter inch away from the Radiator, you're only using a 17" circle in your radiator to cool your engine.

On the Flex Fan. It should work just fine for the symptoms you have described. A "Flex Fan" is designed to flatten out as the fan's rpm increases and to pull LESS air as it does. [quote]

x2

I had a flex fan on a 331 SBC and was racking the throttle from beside the roadster. The fan blades flexed foward and cut into the radiator. Thankfully I was sprayed with warm water, not hot!! :shock:

roadkill2 07-10-2013 07:09 AM

[quote="oldandtired"][quote="roadkill2"]

In other words, if you have a 17" fan and it's a quarter inch away from the Radiator, you're only using a 17" circle in your radiator to cool your engine.

On the Flex Fan. It should work just fine for the symptoms you have described. A "Flex Fan" is designed to flatten out as the fan's rpm increases and to pull LESS air as it does.


x2

I had a flex fan on a 331 SBC and was racking the throttle from beside the roadster. The fan blades flexed foward and cut into the radiator. Thankfully I was sprayed with warm water, not hot!! :shock:
You had one with the long skinny rectangular blades, didn'tcha? Like I said, you get a lot more efficiency from a shrouded mechanical fan if it's back aways from the radiator. Basically, you get to use ALL of the radiator, not just the area the fan pulls air through directly in front of the fan.

I learned all this from my time at "Hard Knocks U" which was about 3 years of street rodding (About 20,000 miles) in a '34 Sedan with a blown SBC . . with a smaller than stock water pump pulley on it .(Unbeknownst to me) I even had a custom built Electric "S" fan from SPAL ($437) . . Bought a shroud from Walker, put on a cut down "Skinny Blade" Flex Fan (had to build a custom fan spacer) and have no more cooling problems . . But I could write a book . . about both the solution(s) and all the goofy and sometimes applicable advice I got from everyone from cooling engineers to little kids . .


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