Thinking of ditching MP viscous fan for flex a lite fan (I read ykf's thread already)

So my car has always run a little hot, even with a fan shroud, 18" MP viscous fan, and 19x26 4 core aluminum radiator. Like 210-220 degrees in traffic, and even once to 230*. But while cruising it stays at around 160-180*. I am in the process of installing two 10" 1100 cfm Zirgo fans in front. In the process I had to remove the viscous fan and radiator. The MP viscous fan seems like it has really small blades, and there is only five blades with large gaps between the blades. When looking at the fan off the motor it was no wonder that a 550 hp 440 motor would run hot. I am not going to want to put this fan back in. I think it is inadequate, and possibly designed only for a factory type 440 motor. I don't totally have faith in the viscous clutch either. It seems weird that I can make the fan move independent of the pulley. I have tested the clutch, and apparently it is doing what it is supposed to do. The MP viscous fan also sits within a half inch of my radiator, and I don't know if that is too close to work right or what. I am thinking of going with this Flex a lite fan. I can call Flex a lite to see how the far the fan should be from the radiator then I can buy whatever space I need. The Flex a lite seems like it would pull more cfm just by looking at it. And because the fan blades straighten out at high rpm it would be like the fan was no longer there. Here is a link to the new fan I am thinking about trying.
http://www.summitracing.com/parts/FLX-1318/


These fans are $40 and a spacer is $15.

Actually, that MP is an 18" fan, and I think I better stick to exactly an 18" fan because I might not have room even for a fan that is only .25" bigger. So I would go with something like one of these.

http://www.summitracing.com/parts/FLX-1818/




http://www.summitracing.com/parts/DER-17018/?rtype=10



There I know that these would fit without any problems. I really do think it would be wise to change fans.

And you would be better off with a fixed seven blade rather than the flex fan.

62MAX said:

And you would be better off with a fixed seven blade rather than the flex fan.

Click to expand...

x2

i went through this a couple years back with my GTX.

after buying and installing and returning a bunch of parts, the best combo i found was a 26" MoPar Rad (re-cored with 3 rows), a stock fan shroud, a 7 blade "hemi" fan (no viscous), and a 70/30 water to rad fluid mix with water wetter.

I drive the car to work in stop and go traffic, in 90* heat, and she doesn't go over 200*. otherwise, she stays right at 185* all the time.

A fix seven blade sounds like it would eat up 45 hp at 6000 rpm.

john.thompson068 said:

A fix seven blade sounds like it would eat up 45 hp at 6000 rpm.

Click to expand...

holy crap!!! really? i knew it ate up hp, but not that much!

where did you see that?

either way, i'm not runnin' my 440 up to 6g's, i'd prob grenade the bastard! lol

MarPar said:

holy crap!!! really? i knew it ate up hp, but not that much!

where did you see that?

either way, i'm not runnin' my 440 up to 6g's, i'd prob grenade the bastard! lol

Click to expand...

LOL!!! Relax. I said it "sounds like" it would eat up 45 hp at 6000 rpm. I really have no idea. But being this street car is caged and tubbed with a healthy motor that I put a lot of money into, I would like to keep it as powerful as possible. If it were a restored cruiser or something along those lines then it wouldn't really matter so much.

john.thompson068 said:

LOL!!! Relax. I said it "sounds like" it would eat up 45 hp at 6000 rpm. I really have no idea. But being this street car is caged and tubbed with a healthy motor that I put a lot of money into, I would like to keep it as powerful as possible. If it were a restored cruiser or something along those lines then it wouldn't really matter so much.

Click to expand...

lol! yeah, my girl is just a street cruiser...not too worried bout loosing a couple, few HP here and there no keep her streetable.

i can appreciate you doing your due diligence, John. i would want to squeeze every last HP out of it as I could too... Mario

I just installed two 10" fans at 1150 cfm a piece, so that should help. You can see them in my other thread. Pretty much, I am ordering a fan that does not look like it is missing two of its blades. At idle, my fan is only turning 850 rpm so that MP fan could use a couple extra blades in my opinion.

OH MAN WHAT THE HELL!!! Now I am furious (sorta).


I have only been cooling my engine with 60% fan speed? No wonder she has run so hot for all this time. That comes straight from the Flex a lite web page about their clutch. That's it man. There is no way that fan is going anywhere near my engine again.

there ya go...

i used the first fan you listed on the first post on my 68 charger rt with a 440 a few years back.here,in vegas,it gets over 110 in the summer and that fan with an enclosed shroud(like yours)with a 16" electric set up as a pusher worked nice.i like the square blade flex fans,the long blade ones dont work worth a dam.

67 coronet said:

i used the first fan you listed on the first post on my 68 charger rt with a 440 a few years back.here,in vegas,it gets over 110 in the summer and that fan with an enclosed shroud(like yours)with a 16" electric set up as a pusher worked nice.i like the square blade flex fans,the long blade ones dont work worth a dam.

Click to expand...

Are you talking about those ones that look like a ninja's flying star with the skinny triangle shaped blades? In just a minute I will call Flex a lite and see what they have to say.

john.thompson068 said:

Are you talking about those ones that look like a ninja's flying star with the skinny triangle shaped blades? In just a minute I will call Flex a lite and see what they have to say.

Click to expand...

ya,dont use the"ninja star"style fans.they dont pull air for crap.

Just got off the phone. The ninja star fans are only for 4 or maybe 6 cylinder engines that are weak. They could not even be used on a 300hp V8. The fan is supposed to sit between half in and half out, or 2/3 in 1/3 out of the box part of the fan shroud. Closeness to the radiator is not a factor, and the measurement for the proper spacer should be based on making the fan sit properly within the box. Obviously, you want to leave about an inch space between the fan and the radiator. I think my MP fan was more like 3/4 to 1/2 though. I just remember it was really close. Also, a good mechanical fan may only pull less than a thousand cfm at idle. And even a heavy duty viscous clutch will only engage at 90% of water pump speed. Switching from a flex fan to no fan at all only saved 15 hp. The guy didn't remember exact numbers, but said a test of a rigid fan versus a flex fan only offered a minimal hp increase. So I will order that seven blade flex fan and spacer.

Well, I measured for the spacer like the tech rep said to, but the way the fan is designed is not the same as the measurements he gave me. However, I am happy with where the fan sits. The fan sits 1/3 in the box, and 2/3 out. The opposite of what the rep told me was optimal. But, I like where it is sitting. Actually, if the box was deep then that would be optimal otherwise the fan could be 4" or 5" away from the radiator which is obviously too far. However, my box is only like 3" deep. If this fan where to be sitting half in or half out, or 2/3 in, the fan would be very close to the radiator and I would need a 2.5" or 3" spacer. I spent a long time looking at the fan mocked up in the radiator and came to the following conclusion. If the fan sat any closer to the radiator, it would narrow down the low pressure zone behind the fan. With the fan sitting 2"-3" away from the radiator like it is now, the fan will create a wider area of low pressure behind the fan. This will cause more air to be drawn in through the corners and sides of the radiator. In addition, I am going to try and build a flat piece for the front side of the back of the radiator and a bottom piece to close off the gap at the bottom of the box. If you look at the above picture you can see the garage floor through the bottom of the radiator. I am going to cut off the very bottom portion of the shroud since all that does really is protect your hand or fingers from getting cut off by the fan. This way, the only way any air will be able to fill the low pressure zone behind the fan is through the radiator. Also, the Flex a lite 1818 has much bigger blades than the MP fan.

Too little timing causes the engine to overheat....Try adding 4 degrees of timing....... There`s a fine line causes detonation...might solve problem....

Pops1967GTX said:

Too little timing causes the engine to overheat....Try adding 4 degrees of timing....... There`s a fine line causes detonation...might solve problem....

Click to expand...

Okay. I will experiment with the timing now that I have resovled the hard crank issue from having a worn out mini starter that was getting heat soaked from an engine the was running in the 220s. I now have a full size starter with heat shield, two electric pusher fans, a more aggressive mechanical fan setup, an improved shroud, and a flushed cooling system with fresh green coolant. Now I can probably take timing from 14 degrees up a little higher without the motor struggling to start.

just switch to ALKY, i have a 12x8 single row radiator. 800 + hp heat block/oil up to 180, on gas swith to Alky and 180 at end of track. dont know how it would function in traffic because i only have 5 gallon tank and burn 2+ gallons in 1/4 mile, good luck finding the problem. i had a aluminum aftermarket fan explode and slice my wrist in high school 14 stitches, i stay away from them. the hard starting is could be caused by timing, i run 38* locked out and starting can be tough sometimes. mini starter will turn over motor mych better than factory. i use mini gear reduction on 14:1 CR. check timing with vacumn advance if you are running a big cam you may not have the correct vacumn to adjust timing.

If that first pic is where your viscous fan sits in the shroud, it's dead wrong. The fan should extend into the shroud 1/2 the width of the fan's blades. Also, the MOPAR viscous fan package is hard to beat. It will cool 600 plus HP when installed and used the correct way, with all the correct elements of a GOOD cooling system.

As performance goes up, so do cooling requirements. Overheating at idle (as you describe) means not enough air flow is making it through the radiator. Although a "better" fan might resolve it, it might not.

Look at cars made through history. Grilles get smaller and smaller. Notice on new cars the under side of the front end between the front "bumper" and and crossmember is closed off. Older cars are very open in this area. The reason for this closing off is to divert more air into the radiator. A hot street engine needs around 4000 CFM give or take to keep cool. Closing off this same area on our older cars will result in more air through the radiator. Know those little "air dams" most new cars come with stickin out from under the front? Same principle. They push air forward and up through the grille and through the radiator. Although our older cars grilles are not getting smaller, their airflow need IS getting bigger with performance upgrades. Your engine is producing almost 200 more HP than a stock Super Commando, but a bigger radiator is all you think it needs? lol

Your "60%" figure is incorrect for the Mopar viscous fan....and ANY thermal controlled clutch fan. I don't give a rat's butt what Flex A Lite says. Here's how a thermostatically controlled viscous fan works. When cold, the clutch pretty much freewheels. This allows minimal fan cooling for quick warmup. Once warm, the bimetal spring on the front of the clutch expands and causes the fan to engage more. It will continue to engage until the fan acheives 100% lockup if needed.

There is also method to the madness of the staggared blade system. This moves more air than a fixed, non staggered blade fan. It breaks the air up into uneven waves and causes a heavier suction drawing in more air. It is a good design and is fully capable of cooling your engine as long as everything else is set up properly. I have seen them on full race cars that put out well over what you say your engine does.

You might go through several different fans and not fix your problem, unless you find out for sure what the problem is. If you're hell bent on putting another fan on, check out Flex A Lite's "Black Magic" electric fans. Those fans REALLY move some air. They are high end electric fans and are not cheap. But if you have a "550 HP 440", you probably won't mind paying a little extra.